Contract Research Findings: Birds


Title:Molecular population genetics, phylogeography, and conservation biology of the mottled duck (Anas fulvigula)
Journal/Year:Conservation Genetics/2001
View:Visit Springer Link - Molecular population genetics, phylogeography, and conservation biology of the mottled duck (Anas fulvigula)
Author(s):Kevin G. McCracken | William P. Johnson | Frederick H. Sheldon
Keywords:Anas fulvigula | Anatidae | incomplete lineage sorting | mottled duck | paraphyly
Abstract:The mottled duck (Anas fulvigula) is a year-round endemic resident of the Gulf Coast and one of two non-migratory dabbling ducks that inhabit North America. To investigate population genetic structure of allopatric mottled duck populations, we collected 5' control region sequences (bp 78-774) from the mitochondria of 219 mottled ducks sampled at 11 widely spaced geographic localities in Texas, Louisiana, and Florida and compared them to each other and to homologous sequences from 4 Mexican ducks (A. diazi), 13 American black ducks (A. rubripes), and 10 mallards (A. platyrhynchos). We identified 57 unique haplotypes composed of 665 or 666 nucleotides in the 246 control region sequences. Of the 665 homologous positions, 8.3% (n = 55) vary among haplotypes, and 98.2% (n = 54) of these occur within the first 351 nucleotides from the 5' end of the outgroup sequence. Neighbor-joining analysis shows a large distal clade (52.5% of mottled ducks sampled in our study) composed of two reciprocally monophyletic clades of mottled duck haplotypes, one of which is endemic to Texas and Louisiana and the other endemic to Florida. No mottled ducks sampled in Florida occur in the clade composed of mottled ducks from Texas and Louisiana or vice versa, suggesting that (1) an enduring geographic split has existed for many years between east and west, and (2) gene flow currently is non-existent (or at least undetectable) across the central Gulf Coast. The remaining 47.5% of mottled ducks sampled in our study branch basally from this derived clade, show substantially less hierarchical structure, and fall into various lineage groups of mixed species composition with no geographic or species-specific pattern. Pairwise FST values corroborate the pattern of strong differentiation observed between Texas/Louisiana and Florida. Our findings are consistent with a pattern of partial lineage sorting from a polymorphic ancestral gene pool reshuffled by hybridizing mallards. Control region data and patterns of divergence in mallard-like species worldwide, furthermore, suggest that mottled ducks are close relatives of Mexican ducks, and in turn nested within black ducks. Genetic similarities to nominate mallards are less likely to be the product of common ancestry, but the result of past hybridization with a dichromatic mallard ancestor that invaded North America from Asia many generations ago. Our findings have several important consequences for the conservation biology of mottled ducks across the Gulf Coast and our understanding of the phylogeography of mallard-like species worldwide.
Management Implications:It is not surprising that a strong geographic element exists in the genetic structure of mottled duck populations, as similar phylogeographic patterns exist in many other species endemic to southeastern North America (e.g., Swift et al. 1986; Avise and Nelson 1989; Walker and Avise 1998). As a year-round resident of the Gulf Coast and one of two non-migratory dabbling ducks that inhabit North America, the mottled duck's population biology naturally lends itself to such structuring. As to whether similar population structuring appears in Mexican ducks or other subtropical North American waterfowl remains open to question. Identification of a strong geographic element in the meta-population structure of mottled ducks has important consequences for conservation of this species across its entire range. First, conservation of mottled ducks in peninsular Florida should be a high priority, given the relatively small size of the Florida population (~56,000; Johnson et al. 1984; Brust 1993) and the large number of endemic haplotypes we identified in our study; 72.7% of mottled ducks sampled in Florida possessed haplotypes endemic to Florida. However, the relatively small size of our sample in Florida suggests that more sampling may identify greater haplotype diversity. Growing urbanization, agricultural pressure, and hybridization with feral mallards make conservation concerns in Florida all the more compelling (Moorman and Gray 1994). Current estimates indicate that there are 500,000-800,000 mottled ducks in Texas and Louisiana (B. Wilson, Gulf Coast Joint Venture unpubl. data), yet mottled ducks in Louisiana and Texas still face threats such as loss and degradation of wetland habitat (Michot 1996). Unlike Florida, hybridization with mallards does not appear to be an immediate concern in Texas or Louisiana; however, evidence concerning hybrid pairing is scarce (Stutzenbaker 1988). Paulus (1988) observed that eight of 225 mottled duck pairs in Louisiana involved mallards; four female mottled ducks were with mallard males, and four male mottled ducks were paired with female mallards. Even so, hybridization is still a factor that could threaten mottled ducks in Texas and Louisiana. Additionally, many counties along the Texas coast are experiencing rapid population growth (Ramos 1999), and populations of feral mallards will likely undergo a concomitant increase. The fact that mottled ducks in Texas/Louisiana and in Florida are evolutionary distinct only heightens the need to be concerned about hybridization. Should mottled duck populations in one of these regions decline to the point where restrictive harvest measures or season closures are warranted, we see no reason why the population inhabiting the other region could not continue to be managed and harvested independently.
Citation:McCracken, K. G., W. P. Johnson, and F. H. Sheldon. 2001. Molecular population genetics, phylogeography, and conservation biology of the mottled duck (Anas fulvigula). Conservation Genetics 2:87-102.
Title:Comparison of methods to detect Pasteurella multocida in carrier waterfowl
Journal/Year:Journal of Wildlife Diseases/2003
View:Visit Journal of Wildlife Diseases, www.jwildlifedis.org/doi/pdf/10.7589/0090-3558-39.1.125
Author(s):Michael D. Samuel | Daniel J. Shadduck | Diana R. Goldberg | William P. Johnson
Keywords:Anas platyrhynchos | avian cholera | carrier | isolation | mallard | Pasteurella multocida
Abstract:We conducted laboratory challenge trials using mallard ducks (Anas platyrhynchos) to compare methods for detecting carriers of Pasteurella multocida, the bacterium that causes avian cholera, in wild birds. Birds that survived the initial infection were euthanized at 2-4 wk intervals up to 14 wk post challenge. Isolates of P. multocida were obtained at necropsy from 23% of the birds that survived initial infection. We found that swab samples (oral, cloacal, nasal, eye, and leg joint) were most effective for detecting carrier birds up to 14 wk post infection. No detectable differences in isolation were observed for samples stored in either 10% dimethysulfoxide or brain heart infusion broth. The frequency of detecting carriers in our challenge trials appeared to be related to mortality rates observed during the trial, but was not related to a number of other factors including time after challenge, time delays in collecting tissues post-mortem, and route of infection. In our trials, there was little association between antibody levels and carrier status. We concluded that swabs samples collected from recently dead birds, stored in liquid nitrogen, and processed using selective broth provide a feasible field method for detecting P. multocida carriers in wild waterfowl.
Citation:Samuel, M. D., D. J. Shadduck, D. R. Goldberg, and W. P. Johnson. 2003. Comparison of methods to detect Pasteurella multocida in carrier waterfowl. Journal of Wildlife Diseases 39:125-135.
Title:Rio Grande wild turkey nesting ecology in Kansas and the Rolling Plains of Texas
Journal/Year:Thesis/2003
View:Download Barnett_2003_TurkeyNestingEcology PDF
Author(s):Terri L. Barnett
Abstract:Habitat change from primarily rangeland to a combination of rangeland and agriculture has occurred in the Panhandle of Texas and southwestern Kansas through the past several decades. Agencies have expressed concern that some Rio Grande wild turkey (Meleagris gallopavo intermedia) populations may be declining. I studied Rio Grande wild turkey nesting habitat at 4 locations; 3 in the Panhandle of Texas and 1 in southwestern Kansas in 2000 and 2001. The Gene Howe Wildlife Management Area (GHWMA) and Salt Fork study areas were chosen to represent stable or increasing populations of wild turkeys, while Cimmaron National Grasslands (CNG) and Matador Wildlife Management Area (MWMA) were chosen to represent possible declining populations. My objectives were to describe nesting and non-nesting habitats among the study areas and to compare characteristics of nesting habitats in relation to nesting success. Females at all study areas selected nest plots with greater shrub cover, higher visual obstruction, and less bare ground cover than adjacent, non-nest plots. Nest site differences were not found to distinguish between possible declining turkey populations and stable populations, except at the CNG study area. Turkey nests at CNG had lower visual obstruction, less shrub density and less dense woody understory vegetation than the other study areas. Nest success was not lower at this study area than the other study areas, although I did find that females nesting in grassland vegetation at CNG were not as successful as females that nested in other vegetation types at that study area. This suggests that lack of other vegetation types may be a limiting factor for turkey population growth at that study area. Juvenile turkeys nested in areas with more bare ground than adult turkeys, and turkeys that nested late in the nesting season used areas with more herbaceous cover than turkeys that nested early in the season at all study areas. Many species return to breed in the same area in successive years, although it is unknown whether Rio Grande wild turkeys (Meleagris gallopavo intermedia) exhibit breeding area fidelity. I examined breeding area fidelity in 43 adult Rio Grande wild turkeys at 4 study areas in Kansas and the Panhandle of Texas during the breeding season of 2000-2002. I examined the hypothesis that females with successful broods would exhibit higher fidelity to their previous breeding area than females that do not produce a successful brood. I found that among all 4 study areas, Rio Grande wild turkeys exhibited overall breeding area fidelity of 74%. Females did not appear to base their return decision on previous year's nesting success. Females that returned to the same area did not exhibit a higher reproductive performance; they were not more successful the following year than females that did not return and their nests did not survive longer before depredation than females that did not return. Spring dispersal distance and home range size was similar between females that returned to the same breeding area and those that relocated to another breeding area. Habitat characteristics were also similar between females that returned and females that did not return to the same area. Because females return to the same area in successive years, it is important to maintain quality nesting habitat to maximize reproductive success.
Management Implications:Rio Grande wild turkeys in general select nesting habitats that provide high visual obstruction surrounding the nest plot and dense understory vegetation. Rio Grande wild turkey females nested in structural composition dependent on the study area. Salt Fork study area nests were located in areas with greater shrub cover than the other study areas. This was due to shinnery oak, sand sagebrush and honey mesquite vegetation being the dominant vegetation at that study area. MWMA study area nests were located in understory cover 2.1-6.0 m in height. This study area consisted largely of honey mesquite vegetation, therefore more nests consisted of dense understory vegetation at this height class than the other study areas. GHWMA study area did not have 1 characteristic that was different from the other study areas, although shrub, forb, and grassland percentages were relatively high. This was largely due to the dominant vegetation being sand sagebrush and grassland vegetation in the upland areas of this study area. We found females at CNG nested in areas with greater canopy cover than the other study areas. This means the majority of nests were located in riparian areas at this study area. Thirty five percent of females nested in upland sand sagebrush and grassland areas and 65% of females nested in riparian areas, although sand sagebrush grassland habitat composed a large portion of this study area. This may indicate that habitat could be limiting turkey populations at this study area. Upland areas at this study area may not be suitable habitats for nests. We did find that CNG nest success was similar to the other study areas, although when vegetation type was separated out at CNG, we found nest success was low in grassland vegetation. Because upland sand sagebrush grassland covers the largest in this study area, it is important to create more adequate nesting habitat by providing high visual obstruction and dense understory vegetation in this habitat. Female wild turkeys exhibit relatively high breeding are fidelity. Wild turkeys appear to exhibit age-biased breeding area fidelity with juveniles exhibiting lower breeding area fidelity than adults. Females did not base their return decision on prior nesting success, nor did returning to the same area increase reproductive performances. Familiarity with the area appeared to be the most important factor in the return decision of Rio Grande wild turkeys. It is, therefore, important to maintain quality nesting habitat in these areas where females return. It is not known, however, whether females will nest in areas with high densities of other nesting females. If females do tend to nest in high densities and return to the same areas in successive years, then it is especially important to manage these areas for quality nesting habitat to maximize reproductive success.
Citation:Barnett, T. L. 2003. Rio Grande wild turkey nesting ecology in Kansas and the Rolling Plains of Texas. Thesis, Texas Tech University, Lubbock, USA.
Title:Avian cholera in waterfowl: the role of lesser snow and Ross's geese as disease carriers in the Playa Lakes Region
Journal/Year:Journal of Wildlife Diseases/2005
View:Visit Journal of Wildlife Diseases, www.jwildlifedis.org/doi/pdf/10.7589/0090-3558-41.1.48
Author(s):Michael D. Samuel | Daniel J. Shadduck | Diana R. Goldberg | William P. Johnson
Keywords:Avian cholera | carriers | Chen caerulescens caerulescens | Chen rossii | lesser snow geese | Pasteruella multocida | Ross's geese | wild waterfowl
Abstract:We collected samples from apparently healthy geese in the Playa Lakes Region (USA) during the winters of 2000-01 and 2001-02 to determine whether carriers of Pasteurella multocida, the bacterium that causes avian cholera, were present in wild populations. With the use of methods developed in laboratory challenge trials (Samuel et al., 2003a) and a serotype-specific polymerase chain reaction method for identification of P. multocida serotype 1, we found that a small proportion of 322 wild birds (< 5%) were carriers of pathogenic P. multocida. On the basis of serology, an additional group of these birds (< 10%) were survivors of recent avian cholera infection. Our results confirm the hypothesis that wild waterfowl are carriers of avian cholera and add support for the hypothesis that wild birds are a reservoir for this disease. In concert with other research, this work indicates that enzootic infection with avian cholera occurs in lesser snow goose (Chen caerulescens caerulescens) populations throughout their annual cycle. Although fewer Ross's geese (Chen rossii) were sampled, we also found these birds were carriers of P. multocida. Even in the absence of disease outbreaks, serologic evidence indicates that chronic disease transmission and recent infection are apparently occurring year-round in these highly gregarious birds and that a small portion of these populations are potential carriers with active infection.
Management Implications:Avian cholera is of particular concern to wildlife managers because most species of waterfowl, raptors, and other birds of wetland ecosystems are susceptible (Botzler, 1991; Friend, 1999). Although the factors that trigger an outbreak are poorly understood, it is commonly believed that weather, stress, and high densities of susceptible birds are important contributors (Botzler, 1991; Windingstad et al., 1998). Increased densities of waterbirds, especially gregarious light goose species, probably increase the risk of disease transmission and outbreak events (Wobeser, 1992). Once an outbreak starts, wetland contamination from diseased birds is the primary source of infection to susceptible birds of all species, although other routes of transmission such as bird-to-bird contact are likely (Wobeser, 1992). Our research demonstrates that some species of waterfowl, especially light geese, are carriers of P. multocida and might be more disposed to avian cholera outbreaks that concurrently or subsequently affect other susceptible species. In addition, the increased abundance of light geese and the large-scale mixing of these populations could enhance the exchange and spread of avian cholera and other disease agents (Wobeser, 1992). Loss of habitat, increased abundance of light geese and other waterfowl, and increased densities of waterbirds are all factors that likely contribute to increasing the risk of avian cholera outbreaks, increasing the risk of infecting other waterbirds in the same wetlands, and increasing the continental distribution of this infectious disease. Current management strategies to control avian cholera losses are reactive, consisting primarily of collecting and disposing of carcasses when outbreaks occur (Wobeser, 1992). Development of proactive or alternative disease management approaches to avian cholera has likely been hindered by uncertainty about the reservoir for the disease. The apparent importance of snow geese as carriers of avian cholera, coupled with the dramatic increase in abundance of midcontinent snow goose populations (Ankney, 1996; Abraham and Jefferies, 1997) and their propensity to occur in large aggregations throughout the year, amplifies the potential role of this species in avian cholera outbreaks. Although the proportion of P. multocida carriers in the midcontinent light goose population is relatively low (3-5%), these populations likely exceed 2.5 million birds (Kelley et al., 2001), containing an estimated 75,000-125,000 P. multocida carriers. Results from our research have implications for other areas in which snow geese occur in large numbers (e.g., California, coastal regions of Texas and Louisiana) and for areas in which avian cholera epizootics are problematic in waterfowl (e.g., Nebraska's Rainwater Basin). Strategies for prevention and control of avian cholera should consider that carrier birds are a likely source of disease outbreaks and disease spread. Management actions that decrease potential disease transmission by separating light geese (and other carrier species) from other species, reducing stress factors that might precipitate epizootic events, and reducing high concentrations of waterfowl on a limited number of wetlands might minimize the effect of avian cholera on waterfowl populations. Because avian cholera affects many waterbird species, further research is needed to determine whether other species, such as white-fronted geese (Anser albifrons) and northern pintails (Anas acuta), frequently associated with avian cholera outbreaks can also serve as a reservoir for this disease.
Citation:Samuel, M. D., D. J. Shadduck, D. R. Goldberg, and W. P. Johnson. 2005. Avian cholera in waterfowl: the role of lesser snow and Ross's geese as disease carriers in the Playa Lakes Region. Journal of Wildlife Diseases 41:48-57.
Title:From the field: the relationship of Rio Grande wild turkey distributions to roads
Journal/Year:Wildlife Society Bulletin/2005
View:Visit JSTOR - From the field: the relationship of Rio Grande wild turkey distributions to roads
Author(s):Matthew J. Butler | Mark C. Wallace | Warren B. Ballard | Stephen J. DeMaso | Roger D. Applegate
Keywords:bias | distance sampling | distribution | line transects | Meleagris gallopavo intermedia | Rio Grande wild turkeys | roads|seasons | sex
Management Implications:Our results suggest that distance sampling from roads during autumn midday and winter AM would results in unbiased estimates of Rio Grande wild turkeys. However, other time periods might result in biased estimates. For example, expect an inflated population estimate from distance sampling along roads for both male and female wild turkeys during the summer midday period because wild turkeys of both sexes used areas < 100 m of roads more than expected. Also, expect an underestimate during those seasons and time periods in which turkeys used areas within 100m less than their availability (e.g., females during spring AM). Thus, autumn midday and winter AM are probably the best times in the Texas Panhandle and southwestern Kansas to conduct distance sampling from roads based on wild turkey distributional patterns. However, other factors such as flocking behavior and visual obstruction need further consideration because they may influence distance sampling as well. Future research should also focus on the degree of bias resulting from the distributional patterns of Rio Grande wild turkeys around roads in particular seasons and time periods.
Citation:Butler, M. J., M. C. Wallace, W. B. Ballard, S. J. DeMaso, and R. D. Applegate. 2005. From the field: the relationship of Rio Grande wild turkey distributions to roads. Wildlife Society Bulletin 33:745-748.
Title:Pastures for upland birds: landowner incentive program restores native species in bermudagrass pastures (Texas)
Journal/Year:Ecological Restoration/2005
View:Download Wagner_etal_2005_Bermudagrass.pdf
Keywords:indigenous species | land restoration | wildlife habitats | wild birds | forage grasses | forbs | seeds | sowing | plant establishment | Cynodon | governmental programs and projects | herbicides | plant ecology | Texas
Author(s):Matt Wagner | Fred Smeins | Brian Hays
Management Implications:After four years of research, demonstration, and technical guidance we have developed the following recommendations: 1) treat Bermudagrass from green-up in early spring through the summer months, depending on temperature and soil moisture; 2) do not treat derelict fields in which many native species are already establishing or treat only selective patches of heavier Bermudagrass cover; 3) use recommended seeding rates, but reduce the seeded species to a few that are relatively inexpensive and likely to establish; 4) contain costs by creating islands of native species planted in strips that are connected to existing patches of habitat, or by seeding blocks within Bermudagrass fields that can expand as Bermudagrass declines; 5) because cost and logistics may preclude restoring areas greater than 5,000 acres (2,000 ha) of prime habitat, focus instead on creating corridors to connect patches of existing habitat that eventually will provide enough space for ground-nesting birds and small- to medium-sized animals to obtain food, cover, and nesting habitat; and 6) keeping in mind that it may take four years or longer to see significant results, implement both short- and long-term adaptive-management approaches (selective mowing, burning, grazing, woody plant control) to maintain the restored areas.
Citation:Wagner, M., F. Smeins, and B. Hays. 2005. Pastures for upland birds: landowner incentive program restores native species in bermudagrass pastures (Texas). Ecological Restoration 23:209-210.
Title:Utility of poult-hen counts to index productivity of Rio Grande wild turkeys
Journal/Year:Proceedings of the National Wild Turkey Symposium/2005
Author(s):Matthew J. Butler | Galon I. Hall | Mark C. Wallace | Warren B. Ballard | Richard S. Phillips | John H. Brunjes, IV | Ross T. Huffman | Rachael L. Houchin | James C. Bullock | Stephen J. DeMaso | Roger D. Applegate | Michael C. Frisbie
Keywords:density | Kansas | Meleagris gallopavo intermedia | poult-hen count | poults/hen index | recruitment | reproduction | Rio Grande wild turkey | Texas
Abstract:Many states use poult-hen counts to index wild turkey (Meleagris gallopavo) population parameters such as reproduction, recruitment, and density. Texas Parks and Wildlife Department (TPWD) personnel have conducted poult-hen counts of Rio Grande wild turkeys (M. g. intermedia) since 1978. In 2000, we began estimating recruitment and reproductive parameters at 3 study sites in the Texas Panhandle and 1 site in southwestern Kansas. During 2000-2004, we estimated reproductive parameters by intensively monitoring 374 radio-tagged wild turkey hens. From annual January-March trapping efforts during 2000-2005, we used the percent of all captured wild turkeys that were juveniles (percent juveniles captured) to index recruitment for 1999-2004. We used the TPWD poult-hen count data from 1999-2004 to estimate poults/hen for counties that contained our study sites. In 2002, we began conducting our own poult-hen counts at the study sites in order to estimate poults/hen at a localized scale. Nesting success rate, mean number of eggs laid per hen, mean number of eggs hatched per hen, percent of juvenile females captured, and percent of juveniles captured were correlated (r² > 0.349, 9 ≤ n ≤ 10, P < 0.05) to our poults/hen estimates. However, none of the reproductive or recruitment parameters were correlated to TPWD poults/hen estimates (r² < 0.143, 13 ≤ n ≤ 16, P > 0.10). Our analyses suggested poult-hen counts could index reproduction and recruitment at localized scales. However, on an ecoregion scale, TPWD poults/hen estimates were unable to index reproduction or recruitment (r² < 0.299, 5 ≤ n ≤ 6, P > 0.15). The inability of the TPWD poults/hen estimates to index reproduction or recruitment at local or ecoregion scales may have resulted from small sample sizes used to calculate TPWD estimates and uneven and inadequate coverage of samples across the ecoregion. If TPWD poults/hen estimates are to be valuable indices at local or ecoregion scales, larger and evenly distributed samples from standardized and randomized surveys must be obtained.
Management Implications:The TTU poults/hen estimate exhibited a linear relationship with many measures of reproduction and recruitment at the local scale. This indicated poult-hen counts can be used as a surrogate for reproduction and recruitment at local scales. However, only about 35-45% of the variation in measures of reproduction was explained by the poults/hen estimates. The ability to explain this amount of variation in reproduction is important in wild turkey populations that are influenced by many ecological forces. However, from a management perspective, this may lack value as an information tool Though measures of recruitment were indices, about 52-62% of variation in the recruitment indices was explained by poults/hen estimates. This could be valuable information for wildlife managers. However, without density estimates, an index of recruitment may be of little value to managers (e.g., McDonald 1964). Also, Caughley (1974) suggested age-ratio trends can appear identical for 2 populations, one irrupting and the other crashing. Thus, we suggest establishment of survey routes with a strict survey protocol that provides for randomization and controls effort. Though randomization and wild turkey behavioral issues arise in road surveys (e.g., Butler et al. 2005), unpublished data (M. J. Butler, Texas Tech University) suggested sample sizes greater than those collected previously by TPWD can be obtained from surveying at least 400 km of roads in wild turkey habitat. This would transform the TPWD poult-hen count into an estimator of the adult population while providing reproduction and recruitment information, the valuable components of population dynamics necessary in species management. Application at ecoregion scales may continue to be elusive because of potential asynchronous productivity and recruitment between local wild turkey populations (T. W. Schwertner, TPWD, personal communication). As our results suggested, pooling across the large, Panhandle Rolling Plains ecoregion will result in a loss of the local variation associated with asynchronous productivity and recruitment across the ecoregion. This potential asynchrony may require state natural resource agencies to evaluate trends at smaller scales. Moreover, if sample sizes are improved, efforts distributed evenly, and survey techniques standardized and randomized, then the TPWD poult-hen count may provide valuable.
Citation:Butler, M. J., G. I. Hall, M. C. Wallace, W. B. Ballard, R. S. Phillips, J. H. Brunjes, IV, R. T. Huffman, R. L. Houchin, J. C. Bullock, S. J. DeMaso, R. D. Applegate, and M. C. Frisbie. 2005. Utility of poult-hen counts to index productivity of Rio Grande wild turkeys. Proceedings of the National Wild Turkey Symposium 9:159-168.
Title:Chronology and use of playas by waterfowl and wetland birds
Journal/Year:Thesis/2006
View:Download Baar_etal_2008_PlayasWaterfowlWetlandBirds.pdf
Author(s):Laura Baar
Abstract:Playa lakes are important migratory stopover and wintering areas for waterfowl and other shorebirds. The purpose of this study was to determine what species of waterfowl, shorebird and other wetland birds use playas in the Texas Panhandle and to determine the timing (chronology) of each species' use of playas. I surveyed playas biweekly during spring migration (February through May), fall migration (August through November) and winter (December through January) from February 2004 - January 2006. In 2004 playas were surveyed monthly during the summer (June through July). In 2005 playas were surveyed twice a month during all seasons. Fifty-six species of waterfowl, shorebirds and other wetland birds were identified on our survey routes. During the 2004 migration, spring peak abundance of waterfowl occurred on 27 February (x̅ = 1,522 birds/playa) and fall peak abundance occurred on 5 November (x̅ = 352 birds/playa). During the 2005 migration, spring peak abundance of waterfowl occurred on 11 March (x̅ = 807 birds/playa) and fall peak abundance occurred on 11 November (x̅ = 515 birds/playa). The 5 most abundant waterfowl observed during my surveys were northern pintail (Anas acuta; 32% of all waterfowl observed during surveys), American green-winged teal (Anas crecca; 22%), mallard (Anas platyrhynchos; 13%), American wigeon (Anas americana; 8%) and Canada goose (Branta canadensis; 6%). The 3 most abundant shorebird species observed during my surveys were American avocet (Recurvirostra americana; 32% of all shorebirds observed), Wilson's phalarope (Phalaropus tricolor; 17%, and killdeer (Charadrius vociferous; 15%). The 2 most abundant wetland birds species observed during my surveys were American coot (Fulica americana; 41% of all wetland birds observed) and sandhill crane (Grus canadensis; 31%). Five species of waterfowl (mallard, northern pintail, blue-winged teal [Anas discors], cinnamon teal [Anas cyanoptera], and northern shoveler [Anas cylpeata]), 3 species of shorebirds (American avocet, killdeer and black-necked stilt; Himantopus mexicanus), and 2 species of waterbirds (American coot and pied-billed grebe; Podilymbus podiceps) used playas for reproduction (young observed) during the summer of 2005. Detailed information on chronology and numbers of birds using playas in this area will provide management agencies vital information needed to make management decisions regarding these species.
Management Implications:My study of the chronology and use of playas by waterfowl and wetland birds furthers our understanding of this important wetland habitat. Waterfowl, shorebird and wetland bird chronology data is vital for habitat planning purposes, establishing population objectives, proper implementation of seasonal management strategies, and for setting hunting season dates. With increasing agricultural development in my study area, further research of the chronology and use of playas by waterfowl, shorebirds and waterbirds will hopefully increase the awareness of both the scientific and public community of the value of playa habitats. Indeed, studies are needed that evaluate the impact of landscape factors on seasonal use of playas by waterfowl and other birds.
Citation:Baar, L. 2006. Chronology and use of playas by waterfowl and wetland birds. Thesis, West Texas A&M University, Canyon, USA.
Title:Male Rio Grande turkey survival and movements in the Texas Panhandle and southwestern Kansas
Journal/Year:Journal of Wildlife Management/2006
View:Visit BioOne Complete Male Rio Grande Turkey Survival and Movements in the Texas Panhandle and Southwestern Kansas
Author(s):Derrick P. Holdstock | Mark C. Wallace | Warren B. Ballard | John H. Brunjes | Richard S. Phillips | Brian L. Spears | Stephen J. DeMaso | Jack D. Jernigan | Roger D. Applegate | Phillip S. Gipson
Keywords:Kansas | Meleagris gallopavo intermedia | movement | Rio Grande | seasonal survival | Texas Panhandle | wild turkey
Abstract:Wildlife managers depend on accurate information regarding wild turkey (Meleagris gallopavo) survival patterns to properly manage turkey populations. Survival patterns of male Rio Grande wild turkeys (M. g. intermedia) have not been studied intensively. Wildlife managers in the Texas Panhandle, USA, and southwestern Kansas, USA, suspected that turkey populations were declining. From January 2000 through August 2002, we studied survival and movement of 107 juvenile male and 115 adult male radiomarked Rio Grande wild turkeys on 4 study sites in the Texas Panhandle and southwestern Kansas. We predicted that males would experience lowest survival during spring and that there would be no difference in survival between age classes. We also predicted that greater male movement rates would lead to lower survival rates. Juvenile males had a higher annual survival rate (0.597 [95% CI hereafter: 0.478-0.716]) than adults (0.364 [0.257-0.472]). Juvenile male survival did not differ among seasons, with survival rates of 0.813 (0.736-0.891), 0.904 (0.837-0.972), and 0.917 (0.838-0.996) for spring, summer, and autumn, respectively. Adult male turkey survival was higher during summer (0.915 [0.859-0.972]) than during spring (0.725 [0.651-0.799]), autumn (0.671 [0.536-0.807]), and winter (0.792 [0.732-0.851]). Males had lower survival rates during seasons when long-distance movements were common. The annual survival rate for turkeys that moved to new core-use areas (0.383 [0.282-0.484]) was lower than that for turkeys that did not (0.535 [0.460-0.609]). Also, survival rates increased with time since relocation of core-use areas. Hunting accounted for 18.5% of all mortalities. However, most (80.7%) mortality was attributed to natural causes, mostly mammalian predation. We suspected most predation was the result of coyotes (Canis latrans) and bobcats (Lynx rufus). Managers in the northern portion of the natural range of Rio Grande wild turkeys should be aware of the presence of natural mortality factors that are evident in lightly hunted populations. Managers interested in increasing the survival of male Rio Grande wild turkeys should concentrate on efforts that will provide needed resources in close proximity to roosts.
Management Implications:Managers should be careful not to overlook potential natural mortality factors that can occur at high rates during both spring and autumn hunting seasons, as these can be easily masked in heavily hunted populations. Managers interested in increasing survival of male turkeys should concentrate on efforts that will provide needed resources in close proximity to roosts in order to decrease the necessity to move to new core-use areas for reasons other than genetic exchange.
Citation:Holdstock, D. P., M. C. Wallace, W. B. Ballard, J. H. Brunjes, R. S. Phillips, B. L. Spears, S. J. DeMaso, J. D. Jernigan, R. D. Applegate, and P. S. Gipson. 2006. Male Rio Grande turkey survival and movements in the Texas Panhandle and southwestern Kansas. Journal of Wildlife Management 70:904-913.
Title:Wading bird time-activity budgets and habitat use during the breeding season in moist soil wetlands at Richland Creek Wildlife Management Area
Journal/Year:Thesis/2006
View:Download Mangiameli_2006_WadingBirdRichlandCreekWMA.pdf
Author(s):Angela Kristina Mangiameli
Abstract:Loss of wetland habitat has had drastic effects on waterbird species that are dependent upon wetlands to survive. Wading birds are excellent indicators of wetland function and overall health, where species such as wood stork (Mycteria americana) have severely declined due to increased loss of suitable habitat. Waterbirds consist of diverse taxonomic groups and their use and occurrence in moist soil managed wetlands may provide insight in quality moist soil wetland habitat that traditionally are managed for wintering waterfowl. During the 2004 and 2005 breeding season, chronology of waterbird occurrence, wading bird behavior and habitat use of moist soil managed wetlands were studied at the Richland Creek Wildlife Management Area. Surveys were conducted for occurrence of waterbirds during spring and summer. Over 40 waterbird species were observed. Wading birds were the predominant group in both years with the highest abundance occurring in May-June. Behavior was measured using time-activity budgets for seven focal species; cattle egrets (Bubulcus ibis), great egrets (Ardea alba), great blue herons (A. herodias), little blue herons (Egretta caerula), snowy egrets (E. thula), white ibis (Eudocimus albus) and wood stork. Over 4,000 focal samples were collected in both years. Behaviors varied among species (P> 0.001) and between years (P> 0.001). Resting and body maintenance were the predominant behaviors among all species except white ibis which showed feeding (>60%) as the predominant behavior. Microhabitat was measured within a 1-m² quadrat where data was collected on the following: distance to edge (m), water depth (cm), tallest emergent plant (cm), percent cover of open water, emergent vegetation, mudflat, and floating vegetation for used and random bird locations. Habitat use varied among species (P> 0.001) (i.e. cattle egret, great egret, snowy egret, white ibis) on moist soil wetlands. Data revealed wading birds utilized habitat consistent of water depths ranging from 4-27 cm in a mix of emergent vegetation and open water. Morphological differences among focal species revealed different habitat variables (i.e. open water, emergent, floating vegetation, mudflats) are required to provide suitable habitat for multiple species. The results from this study have generated important data to further enhance what is known about foraging behaviors and techniques among wading birds as well their importance as indicators for wetland health. However, few studies have examined wading bird use of moist soil managed wetlands and due to the fact these wetlands were utilized by an endangered species (i.e., wood stork) then future management may include these birds.
Management Implications:Knowledge of activity patterns has important consequences for wetland conservation, protection and management, as they provide insight into the functional role of wetland habitats for waterbirds (Caraco 1979, Espino-Barros and Baldassarre 1989). This study provides an initial description of behavioral patterns of wading birds during the breeding season on moist soil managed wetlands. In general, wading birds engaged in (1) feeding and food acquisition behaviors and (2) resting and body maintenance behaviors, both of which are generally related to physiology, energy conservation strategies, and migration strategies. As few studies have examined wading bird behavior on moist soil managed wetlands, knowledge of behavioral responses to such management is essential. Although waterbird diversity increases, in response to moist soil management strategies, have been documented in natural wetlands (i.e. playas, Anderson and Smith 1999) and in created wetlands (Stewart and Kantrud 1973), how they use those wetlands is equally important, as those data will indicate relative habitat quality. Moist soil management can be beneficial as it may create pools with high prey densities (Bryan et al. 2000), which are critical for foraging wading birds. As such, increased feeding time, as opposed to increased time resting, would indicate high prey availability, and therefore high foraging habitat quality. Because of the differences in water depths, drawdown regimes, and overall management strategies within each moist soil managed wetland at RCWMA, the WMA operates in a "wetland complex". In general, wading birds benefit from moist-soil management in a wetland complex, which provides diverse habitat for a diversity of waterbirds (Voigts 1976, Fredrickson and Reid 1986, Bowyer 2001, Bowyer 2002). However, dramatic hydrological changes (i.e., water levels too low or too high) may alter behavioral responses among wetland dependent species. For example, wood storks are sensitive to water level changes, where large colonies will abandon a site, even during the breeding season (Kushlan et al. 1975). As such, future moist soil management strategies may consider potential impacts on species of concern, such as wood storks. Although increased flooding over most of the annual cycle may benefit larger wading birds, other morphologically different waterbirds may not respond (i.e., shorebirds, small waders). If wetlands are not drawn down where decomposition and seed germination do not occur at some point during the annual cycle, as observed in wetland one, then the hydrophytic composition may be altered and submergent vegetation becomes more dominant rather than emergent seed producing plants. As such, as waterfowl migrate through and winter at RCWMA, these wetlands may only attract diving ducks and nonmigratory wading birds, thus limiting the potential for greater waterbird diversity. The Texas coast is a key wintering area for many wading birds (Mikuska et al. 1998) and the RCWMA is an ideal stopover site during migration and during summer. As wading birds specifically select wetlands suitable for breeding, rather than arbitrary chosen sites (Hestbeck 1995, Niemuth and Solberg 2003), current management practices should consider wading bird migration and breeding. When moist soil management techniques are implemented, various habitats became available. For example, flooded agricultural fields may provide a rich food supply, open water habitats create new edge habitat, and when water levels decline, exposed shallow water and mudflats allow waders to walk and readily search for fish, reptiles, amphibians,and large invertebrates (Weller 1999). As additional wetlands are created at RCWMA, wading bird abundance should increase, However, beyond just abundance, time spent in different behaviors should provide insight into the functionality and overall quality of created moist soil managed wetlands.
Citation:Mangiameli, A. K. 2006. Wading bird time-activity budgets and habitat use during the breeding season in moist soil wetlands at Richland Creek Wildlife Management Area. Thesis, Stephen F. Austin State University, Nacogdoches, USA.
Title:A genetic and isotopic characterization of eastern and western white-winged dove breeding populations to determine wintering ground distribution and population genetic structure
Journal/Year:TPWD Final Report/2007
View:Download Carleton_MartinezdelRio_2010_WWDO.pdf
Author(s):Scott Carleton | Carlos Martinez del Rio
Abstract:Migratory birds spend as much as 80% of their lives on wintering grounds or in transit to and from breeding areas. Very little is still known about the biology of most of these species outside the breeding season. The white-winged dove (Zenaida asiatica) breeds in North America and has migratory populations that breed in the United States and winters across southern Mexico and northern Central America. In the last century, this species has experienced extensive population explosions and declines. These population fluctuations are, to a large extent, consequences of the reliance of this species on human-modified landscapes that can undergo rapid changes. Although the potential consequences of these changes in land use have been well described in the breeding grounds, very little is known about the biology of these birds while inhabiting wintering areas. Traditional methods for tracking migratory birds, such as band recoveries, have yielded few returns and the distribution of migratory white-winged doves on wintering grounds is still poorly understood. A new molecular tool, stable isotope analysis, is proving to be very effective in linking breeding and wintering grounds in migratory bird species. Variation in temperature, humidity, and rainfall across the breeding range of white-winged doves in North America creates unique hydrogen isotope signatures in plants and sources of water. These hydrogen isotope signatures are then incorporated into feathers grown prior to migration. The result is that every bird becomes a banded bird, traveling to and from the wintering grounds, with a unique signature of its geographic breeding origin contained within its feather tissues. We used this technique to characterize the breeding ground feather hydrogen isotope signatures of the eastern population of white-winged doves (Zenaida asiatica asiatica) from Brownsville to El Paso, Texas and the western population (Zenaida asiatica mearnsii) from Tucson to Yuma, Arizona. We discovered a gradient of decreasing hydrogen isotope signatures in bird feathers collected from Houston, Texas to Yuma, Arizona. Hydrogen isotope values ranged from -50 to -90% in Texas and from -80 to -120% in Arizona. Discriminant analysis correctly identified 1080 out of 1200 feather samples as belonging to either the Eastern or Western populations based on hydrogen isotope values. In addition, feather hydrogen isotope analysis across the years 2003, 2004, and 2005 revealed little inter-annual variation. We are currently undertaking the final stage of this project by collecting feather samples from white-winged doves across southern Mexico. By linking feather hydrogen isotope values collected in Mexico to those characterized on the breeding grounds we hope to determine the distribution of the Eastern and Western populations on the wintering grounds. Determining the distribution of this species in Mexico is an important first step in understanding its biology and facilitating answers to future research and management questions. Funds for this project were provided in part by the White-winged Dove Stamp Fund of the Texas Parks and Wildlife Department, University of Wyoming, Arizona Game and Fish Department, and the National Fish and Wildlife Foundation.
Management Implications:Stable isotope analysis has incredible potential in wildlife management. This study highlights the differences that exist in populations across their breeding range that can be detected in a molted flight feather that can be collected at check stations, during hunter checks by wardens and wildlife biologists, or through a hunter wing survey program. When populations of birds can be differentiated across the landscape, isotope analysis has huge potential to track seasonal movements and even reveal where birds were the previous breeding season. For white-winged doves, this study found a large gradient in feather isotope signatures from the eastern to the western extent of their breeding range. Had we been able to collect feather samples across this species entire wintering range and describe the isotope signatures of resident doves in southern Mexico, description of the wintering ground distributions would be possible. Because of this limitation, samples were small and only covered a small geographic area that encompassed more of the western populations wintering range and revealed a number of doves that had signatures represented by desert and agricultural doves. We are continuing to analyze the data set and are collaborating with Keith Hobson with the Canadian Wildlife Service using a data set on house sparrow feathers from Mexico as a surrogate for resident dove signatures. Probably the most contrasting signatures were found between doves in southern Arizona. The distinct signatures in feathers between desert and agricultural habitats allow managers to differentiate desert or agriculture origin doves and determine the proportion of desert and agriculturally produced birds in fall harvests. While these results will likely not change how desert/agricultural doves are managed, i.e. as two separate populations, they do provide a tool that managers can use in the future should the need arise to differentiate habitat/resource use and differences in vital rates between populations. In addition, climate change models predict that habitats at the extremes, cold and hot, will be affected most. If this prediction is indeed true, populations of doves that utilize Sonoran desert habitat may be at greater risk due to habitat loss and reduced availability of resources during the hottest time of the year. Isotope analysis can and would be a valuable tool to identify doves utilizing these very isotopically and physically contrasting habitats. AFLP analyses results agree with those found using microsatellite DNA (Tankersley 2000). The results of this study indicate minor genetic differences that would be expected for a species that inhabits a large geographic range with populations more closely located to each other having a higher degree of similarity than populations more distantly associated. For migratory game bird managers, the results of this study indicate that management of white-winged doves as two distinct sub-units is not warranted and that white-winged doves can be managed as a single population exhibiting typical genetic relationships for a widely distributed species across their geographical range.
Citation:Carleton, S., and C. Martinez del Rio. 2007. A genetic and isotopic characterization of eastern and western white-winged dove breeding populations to determine wintering ground distribution and population genetic structure. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Behavior of migrant shorebirds in saline lakes of the Southern Great Plains
Journal/Year:Waterbirds/2007
View:Download Andrei_etal_2007_ShorebirdsSalineLakes.pdf
Author(s):Adrian E. Andrei|Loren M. Smith|David A. Haukos|William P. Johnson
Keywords:American Avocet | Least Sandpiper | Lesser Yellowlegs | New Mexico | saline lakes | shorebirds | Southern Great Plains | Texas | Wilson's Phalarope
Abstract:We recorded and compared diurnal and nocturnal time-activity budgets of American Avocet (Recurvirostra americana), Lesser Yellowlegs (Tringa flavipes), Least Sandpiper (Calidris minutilla), and Wilson's Phalarope (Phalaropus tricolor) on 21 saline lakes in the Southern Great Plains, USA, during spring and summer/fall 2002 and 2003 to examine importance of saline lakes as migratory stopover sites. All four species spent most of their time feeding (47-70%) and resting (7-37%) by day and at night during spring and fall migrations. Little time was spent in other behaviors. Time budgets differed among species and between seasons, likely due to different energy needs. Time spent foraging varied seasonally between saline lakes and freshwater playas for American Avocets and Least Sandpipers, likely due to differences in vegetation cover and availability of prey between these wetland types. For most species, time spent foraging and resting differed between day and night. Therefore, extrapolating diurnal activity budgets to the entire 24-hour period and from one type of habitat to another within the same region is not recommended. Saline lakes are used by migrant shorebirds as stopover sites where they replenish lipid stores. Conservation efforts should focus on preserving these unique wetlands and the freshwater springs that discharge in them.
Management Implications:Because activity budgets may differ among species, seasons, wetland types, and between day and night, researchers and conservation planners should exercise caution when extrapolating data from one type of habitat to another within the same region. Our findings, in addition to those of Kostecke and Smith (2003), show that nocturnal data should be included when examining shorebird energy needs and that diurnal activity data (Davis et al. 1989; Davis and Smith 1998a) should not be extrapolated to the entire 24-h period. Conservation of shorebirds migrating through the Southern Great Plains (Davis and Smith 1998b; Andrei et al. 2006) should include preservation and restoration of saline lakes and the springs fed by the Ogallala aquifer. Decreasing water withdrawals from the aquifer in the vicinity of the lakes and throughout the region, easements and purchase of water rights by conservation organizations and government agencies, and restoration of aquifer recharge through the playa lakes (Osterkamp and Wood 1987; Wood and Osterkamp 1987; Wood 2000) are needed to protect these habitats.
Citation:Andrei, A. E., L. M. Smith, D. A. Haukos, and W. P. Johnson. 2007. Behavior of migrant shorebirds in saline lakes of the Southern Great Plains. Waterbirds 30:326-334.
Title:Prey use and provisioning rates of breeding ferruginous and Swainson's hawks on the Southern Great Plains
Journal/Year:The Wilson Journal of Ornithology/2007
View:Download Giovanni_etal_2007_PreyProvisioningHawks.pdf
Listing of articles and allowing distribution of PDFs published by the Wilson Journal of Ornithology has been approved by the editor on behalf of the Wilson Ornithological Society
Author(s):Matthew D. Giovanni|Clint W. Boal|Heather A. Whitlaw
Abstract:We collected diet data at 12 Ferruginous Hawk (Buteo regalis) and 14 Swainson's Hawk (B. swainsoni) nests in a short-grass prairie and agricultural community in the panhandle area of northwest Texas and southwest Oklahoma, and in northeastern New Mexico during the 2003-2004 breeding seasons. We documented 959 Ferruginous Hawk and 1,058 Swainson's Hawk prey deliveries during ~5,618 hrs of video monitoring. Ferruginous Hawks delivered 10.0 ± 0.7 (x̅ ± SE) prey species per nest and typically larger prey. Swainson's Hawks delivered 13.4 ± 1.1 prey species per nest and typically smaller prey. There was a dietary overlap (Simplified Morisita Index [CH]) of 0.31 in prey species delivery frequency and 0.56 in prey species' biomass. Ferruginous Hawks made 4.6 deliveries/day at 480 g/delivery whereas Swainson's Hawks delivered smaller prey items (147 g/delivery) but more frequently (7.0 deliveries/day). Deliveries/day and mass/day increased with increasing brood sizes of both species, but deliveries/day/nestling and mass/day/nestling decreased. Provisioning rates did not vary significantly over the nestling period. These data represent the most accurate diet quantification to date for Ferruginous and Swainson's hawks. Ferruginous Hawks used a larger array of prey types than shown in other studies based on indirect diet analysis methods. The low interspecific diet overlap suggests that prey is partitioned, which may facilitate the well-documented sympatric distribution of the two species.
Management Implications:Ferruginous Hawks preyed primarily upon prairie dogs and pocket gophers. These species should be considered when making management decisions for breeding and non-breeding Ferruginous Hawks on the Southern Great Plains. Numerous studies have shown that Ferruginous Hawks tend to have lower reproductive success and emigrate following primary prey population declines (Smith et al. 1981, Schmutz and Hungle 1989, Woffinden and Murphy 1989, Cully 1991). These trends may be particularly important where prairie dogs are a primary breeding or non-breeding season prey species, as they are still subject to unregulated eradication and control efforts throughout most of their range (Kotliar et al. 1999).
Citation:Giovanni, M. D., C. W. Boal, and H. A. Whitlaw. 2007. Prey use and provisioning rates of breeding ferruginous and Swainson's hawks on the Southern Great Plains. The Wilson Journal of Ornithology 119:558-569.
Title:The importance of playas to migratory birds
Journal/Year:Playa Lakes Symposium 2007
View:Download Johnson_2007_PlayasMigratoryBirds.pdf
Author(s):William P. Johnson
Abstract:Playa lakes are critical to maintaining biodiversity on the Southern Great Plains. Although playas are important to wintering waterfowl, their most important function with respect to migratory birds is to provide areas for them to rest and forage during migration. Not only are bird numbers greatest during migratory periods, but nutrients acquired by shorebirds and waterfowl during fall migration may contribute to overwinter survival. Moreover, nutrients acquired during spring may likely contribute to reproductive performance and population recruitment. Loss of playa productivity due to sedimentation or other forms of habitat degradation has the potential to negatively impact the continental populations of certain species, such as Northern Pintails (Anas acuta).
Management Implications:It is not unreasonable to assume that many species of waterfowl and shorebirds, not just Northern Pintails, might be impacted at a continental scale by declining habitat conditions on playas. For most shore birds and some waterfowl, however, we lack the kind of meaningful population data that will enable us to determine what percent of the population utilizes playas during migration (Smith 2003). Even so, Skagen (2006) and Haukos et al. (2006) emphasized the importance of conserving all interior wetlands, such as playas, for migrating shorebirds and waterfowl. Any reduction in playa functions or productivity has the potential to compromise the ability of migratory shorebirds and waterfowl to acquire the nutrients necessary to complete migration, and perhaps compromises the sustainability of migratory bird populations.
Citation:Johnson, W. P. 2007. The importance of playas to migratory birds. Pages 13-18 in Playa Lakes Symposium. K. A. Cearley, editor. Texas Cooperative Extension, 23-24 October 2007, Amarillo, USA.
Title:Time-activity budgets, body condition, and lipid prediction models of wintering diving ducks on East Texas reservoirs
Journal/Year:Thesis/2007
View:Download Crook_2007_DivingDucksThesis.pdf
Author(s):Shaun L. Crook
Abstract:To date, no work has focused specifically upon behavior and body condition of diving ducks wintering on east Texas reservoirs. During November - March, 2003-2004 and 2004-2005 seasons, I (1) developed time-activity budgets, (2) estimated body condition, and (3) developed lipid prediction models for canvasback (Aythya valisineria), lesser scaup (Aythya affinis), and ring-necked duck (Aythya collaris) during winter on Toledo Bend, Sam Rayburn, and B.A. Steinhagen Reservoirs. Behaviors were measured for each species using focal individual sampling during both study years. More than 1220 focal samples were collected for canvasback (n=640), lesser scaup (n=313), and ring-necked duck (n=271) during approximately 50 hours of observation during this study. Behaviors varied among species (P < 0.001) in the proportion of time spent feeding and locomoting. Ring necked duck spent almost 30% of the time feeding, whereas canvasback spent only 19% of the time feeding, and nearly 40% of the time in locomotion activities. Lesser scaup tended to spend intermediate amounts of time in both behaviors. Time spent in loafing, comfort, and sleeping behaviors were similar among species (P > 0.140); combined these behaviors accounted for 31-34% of time activity budgets for all species combined. Few courtship or agnostic behaviors were observed for any species in either year. A total of 248 ducks were collected between 8 November 2003 - 23 January 2004 and 3 November 2004 - 2 March 2005 to estimate body condition and develop lipid prediction models from morphological and internal tissue measures obtained from the birds. In general, average lipid content of diving ducks during this study ranged between 19-35%, depending on species and age and sex within species. Several significant models (P < 0.05) were successfully developed using a combination of morphological and internal fat and tissue measures. Model variables differed depending on species and age and sex within species, although skin mass was an important variable in most models, and alone accounted for 69-86% of the variation in percent lipid content. This study generated important information of how diving ducks utilize reservoirs in east Texas. Diving ducks in this study had time-activity budgets similar to other studies, and also maintained relatively high lipid levels. This information may suggest that these reservoirs are providing sufficient habitat for wintering diving ducks. However, little is known of the quality/quantity habitat these reservoirs are providing for wintering diving ducks. Therefore, future research is needed to better understand the type of habitat these reservoirs are providing.
Management Implications:Toledo Bend, Sam Rayburn, and B. A. Steinhagen Reservoirs are wintering areas to a substantial number of diving ducks and appear to provide suitable winter habitat. However, a potential problem noted in this study was the relatively high rates of locomoting, possibly due to disturbance. Currently, on these reservoirs there are few restrictions on hunting or water-based recreation. During this study, I regularly observed disturbances from boaters, mainly fishermen and hunters. Therefore, because of the adverse effects of disturbance and the possible increase in water-based recreational activities on these reservoirs, future restrictions on human activities may need to be imposed. This is probably most critical in late winter and early spring when birds are trying to acquire reserves for migration and reproduction. Further research is needed to (1) examine nocturnal foraging activities, (2) quantify and map the habitats in which birds are actually foraging, (3) perform nutritional analyses of food items likely encountered/used by these species, and (4) quantify disturbance. Such information, along with behavior and body condition data will give managers a clearer understanding of the quantity of habitat these man-made reservoirs are providing for wintering diving ducks. Although plucked skin and omental fat mass are important variables in predicting lipid content, they are time consuming and require sacrificing the bird. However, few studies have developed reliable models using easily obtainable morphological measurements. Likewise, I developed few reliable models that incorporated easily obtainable morphological measurements, where models were inconsistent within and among species in this study. Therefore, models incorporating a combination of morphological, internal fat, and tissue mass measurements should be used to predict lipid content in diving ducks wintering on east Texas reservoirs. As sample sizes of some age and sex classes used in this study were small, future research which includes more birds from each age/sex class is needed to develop efficient and reliable models. Quantity and quality of habitat these reservoirs are providing for wintering diving ducks should be examined. Such data would provide information to develop management decisions to enhance habitat on these reservoirs. Research should concentrate on food abundance, availability, and utilization of submergent and emergent vegetation on these reservoirs.
Citation:Crook, S. L. 2007. Time-activity budgets, body condition, and lipid prediction models of wintering diving ducks on East Texas reservoirs. Thesis, Stephen F. Austin State University, Nacogdoches, TX, USA.
Title:Winter roosting ecology of Rio Grande wild turkeys in the Rolling Plains of Texas
Journal/Year:Thesis/2007
View:Download Swearingin_2007_WinterRoosting.pdf
Author(s):Ryan Matthew Swearingin
Abstract:A crucial time for Rio Grande wild turkeys (Meleagris gallopavo intermedia) is during the winter when flocks > 200 birds congregate at traditional winter roosts. As wild turkey home ranges are smallest during this time of year, there is a need for appropriate forage and security habitat in close proximity to suitable roosting habitat. In addition, it is believed that eastern cottonwood (Populus deltoides), the favored roost tree species in the Rolling Plains, may be declining due to altered river flow regimes, the invasion of exotic species such as Russian olive (Elaeanus angustifolia) and saltcedar (Tamarix chinensis), and overgrazing. Consequently, a greater understanding of the critical vegetative characteristics of winter roost sites is needed. We conducted fieldwork on 3 study sites located in the Rolling Plains of Texas during September through flock breakup in April from 2004-2006. We gathered roost locations via radio telemetry to identify movement patterns and to detect active winter roosts. We measured roosting habitat at 32 roost sites and 32 randomly selected non-roost sites. We measured tree height, tree diameter, canopy cover, tree decay, area of the stand in which the roost occurred (stand area), percent litter cover, and percent shrub cover. We linked winter roost use (presence-absence) with habitat variables representing forest and vegetation structure at roost sites by creating explicit habitat models. We developed 44 a priori logistic regression models. We used second-order Akaike's information criterion (AICC) for model selection. We found tree height, tree diameter, stand area, and percent litter were all important predictors of roost sites. Based on these findings an appropriate management strategy should include the conservation of large, open-understory, riparian stands of trees. Those stands should contain the tallest, largest diameter trees available. We also suggest that young stands of preferred roost tree species be protected to provide future potential roost sites when current roosts become unsuitable to wild turkeys. Winter flock congregations of Rio Grande wild turkeys are larger than other turkey subspecies. Roosting flocks > 200 birds are not uncommon. However, thorough evaluations of when flocks congregate on winter areas and the potential climatic factors that drive congregation are lacking. We used opportunistic flock counts (n = 3,047) and roost counts (n = 101) to identify timing of winter flock congregation, peak concentrations, and breakup of winter roosts. We also examined possible relationships between roost/flock counts and climatic variables. We found that winter congregation occurred from 15 November through 28 February with peak concentrations occurring from 16 January through 1 March, and flock breakup occurred from 1 March through 15 April. We suggest that if using roost counts for abundance estimation that surveys be conducted from 16 January though 1 March.
Management Implications:Since appropriate size classes of key roost vegetative components vary across the wild turkey's range, we suggest optimizing habitat relative to the surrounding area rather than supplying managers with specific, somewhat arbitrary, management goals. We suggest conservation-based rather than manipulative management recommendations. The largest stands with the tallest, largest diameter trees available should be conserved. Those sites with the lowest amount of visual obstruction in the understory should also be given priority. Understory visual obstruction is the most easily manipulated variable that we examined. We suggest if brush control is to be implemented at roost sites that it be conducted during the spring/summer months after most winter residents have dispersed for the breeding season. This will minimize disturbance to winter concentrations. Protection of areas where cottonwood recruitment has occurred or is most likely should help to insure that optimal roost sites will be available in the future. The eastern cottonwood is an r-selected species that relies on flood events to prepare seedbeds for seed germination (Amlin and Rood 2002). As a result, flood prone areas containing bare soils should be monitored for cottonwood recruitment. When young seedlings are found, the area should be excluded from grazing pressure so that young seedlings are protected from herbivory. Riparian brush control may also increase the likelihood of cottonwood regeneration and provide roost trees for the future. Peak winter concentrations of wild turkeys at winter roosts occurred from January-February. This appears to be the best time to conduct roost counts. Additionally, since cold temperatures impact wild turkey concentrations, roosts should be counted during the coldest portion of the specified peak period for the greatest likelihood of the highest densities of wild turkeys using major roosts.
Citation:Swearingin, R. M. 2007. Winter roosting ecology of Rio Grande wild turkeys in the Rolling Plains of Texas. Thesis, Texas Tech University, Lubbock, USA.
Title:Migration chronology of waterfowl in the Southern High Plains of Texas
Journal/Year:Waterbirds/2008
View:Download Baar_etal_2008_MigrationChronologyWaterfowl.pdf
Author(s):Laura Baar | Raymond S. Matlack | William P. Johnson | Raymond B. Barron
Keywords:dabbling ducks | diving ducks | geese | migration chronology | playas | Southern High Plains | Texas | wintering waterfowl
Abstract:Migration chronology was quantified for 15 waterfowl species on 58 playa wetlands in the Southern High Plains of Texas from February 2004 through April 2006. Abundance of each species was estimated on playas once every two weeks during the nonbreeding season (16 August to 30 April); presence of ice was also recorded. Dabbling ducks were most common (N = 250,668) and most tended to exhibit either a bimodal migration pattern (lower abundance in winter than during fall and spring passage) or a unimodal pattern (one defined peak). Abundance of the most common dabbling ducks was skewed toward late winter and spring. Most species of diving ducks (N = 15,128) tended to exhibit irregular migration patterns. Canada Geese (both Branta canadensis and B. hutchinsii, N = 15,347) had an abundance pattern that gradually increased, peaking in midwinter, and then decreased, which is typical for a terminal wintering area. Ice was most common on playas during the first half of December, which coincided with the lowest winter abundance in dabbling ducks. Data from this study will support management efforts focused on playa wetlands, including the development of population goals and habitat objectives that span the entire non-breeding season.
Management Implications:Although the general migration patterns of waterfowl are interesting, the data's greatest potential will be to support planning efforts focused on playa conservation. Some wintering ground joint ventures (partnerships) working under the auspices of the North American Waterfowl Management Plan (North American Waterfowl Management Plan, Plan Committee 2004) have been able to link temporal population objectives, such as those coinciding with mid-winter waterfowl surveys, to migration chronology data to develop population and habitat goals that span migration and wintering periods (Esslinger and Wilson 2001; Wilson and Esslinger 2002). Similarly, migration chronology has been used to refine carrying capacity models for Redheads and Northern Pintails on critical wintering areas (Michot 1997; Miller and Newton 1999). Although the Southern High Plains has long been viewed as an important wintering area (Bellrose 1980), data from this study suggest the region is more important to spring migrants than it is to wintering waterfowl; incorporating this migration chronology information into ongoing planning efforts by the Playa Lakes Joint Venture will likely bear this out.
Citation:Baar, L., R. S. Matlack, W. P. Johnson, and R. B. Barron. 2008. Migration chronology of waterfowl in the Southern High Plains of Texas. Waterbirds 31:394-401.
Title:Minimum patch size thresholds of reproductive success of songbirds
Journal/Year:Dissertation/2008
View:Download Butcher_2008_GCWReproductiveSuccess.pdf
Author(s):Jerrod Anthony Butcher
Abstract:Preservation of large tracts of habitat is often recommended for long-term population viability of area-sensitive species. Large tracts may not always be available. Smaller patches, though not able to contain a viable population individually, may contribute to overall regional population viability if within the small patches pairs could successfully reproduce. By definition, area-sensitive species should have a minimum patch size threshold of habitat below which they will not likely reproduce. Two potential causes for positive relationships between patch size and production are inverse relationships between patch size and brood parasitism and patch size and food availability. My objectives were (1) to determine the minimum patch size thresholds of reproductive success for golden-cheeked warblers (Dendroica chrysoparia), black-and white warblers (Mniotilta varia), and white-eyed vireos (Vireo griseus); (2) to determine whether thresholds for occupancy, territory establishment by males, or pairing success were indicative of thresholds of reproduction; (3) to determine whether the proportion of pairs fledging brown-headed cowbird (Molothrus ater) young was related to patch size, and (4) to determine the effects of patch size on food availability (i.e., arthropod abundance). The Vickery index of reproductive activity was used to determine reproductive activity of each male or pair and to quantify parasitism occurrences. I collected arthropods using branch clipping to assess the relationship between patch size and arthropod abundance. I found minimum patch size thresholds of reproductive success for golden-cheeked and black-and-white warblers, but not for white-eyed vireos. Minimum patch size of reproductive success was between 15 and 20.1 ha. Minimum patch size thresholds for occupancy, territory establishment by males, and pair formation were not consistent with thresholds for reproductive success. I found no relationships between patch size and cowbird parasitism or patch size and arthropod biomass. Conservation practices for target species based on thresholds of occupancy, territory establishment, or pair formation may not address issues of reproduction. The ability to identify thresholds of reproductive success for target species could be useful in conservation and management in multiple ways including setting goals for retention and restoration of a target species' habitat patch size.
Management Implications:Because both warblers have relatively uniform habitat requirements across their distribution ranges (Kricher 1995, Ladd and Gass 1999), patch size relationships observed in this study should hold across much of their ranges. Managers involved in juniper clearing in east-central Texas particularly, and in forest removal in general, should be cautious not to decrease patches below 20 ha. Because patches below the threshold of reproductive success were occupied by golden-cheeked warblers, research is needed to determine the role that such patches play in population dynamics of golden-cheeked warblers.
Citation:Butcher, J. A. 2008. Minimum patch size thresholds of reproductive success of songbirds. Dissertation, Texas A&M University, College Station, USA.
Title:Nest survival of white-winged doves in South Texas
Journal/Year:TPWD Final Report/2008
View:Download Collier_etal_2008_WWDNestSurvival.pdf
Author(s):Bret Collier | Markus Peterson | Nova Silvy
Abstract:Harvest management of migratory game birds requires that managers derive relationships between population demographic parameters and use these estimates in a predictive framework to evaluate annual change in population size. We estimated daily nest survival for white-winged doves (Zenaida asiatica) for use in development of models for predicting annual recruitment for formal harvest management planning and evaluation. We used fates from 7,864 white-winged doves nests monitored between 1966 and 2002 and found that daily nest survival varied between the early breeding months (May-June) and late breeding months (July-Sept) and exhibited variation over 5-year intervals. Daily survival estimates ranged from 0.94 (0.937-0.947) to 0.99 (0.998-0.999) giving overall nest success estimates between 0.19 and 0.96. Our nests, which were in native habitats, had a considerably higher median nest survival than estimates from urban populations. For white-winged doves, the influence of environmental factors on natality and mortality is critical to understanding population dynamics and for future management planning and monitoring. Our results provide a foundation for development of initial strategies for monitoring white-winged dove reproductive parameters across their range.
Management Implications:Because Texas is the primary stronghold for white-winged doves in the United States, our nest survival results provide a foundation of productivity information for use in population models and adaptive management for white-winged doves. Our nests in native habitats had a considerably higher median nest survival than estimates from urban populations. Additionally, our results suggest changes in breeding chronology, which also impacts designs for population estimation. As white-winged doves are increasingly found in urban environments, future work should focus on evaluating differences in population parameters between native and urban habitats and the impact changing breeding chronology have on populations. In addition, we suggest standardized data collection regarding reproductive effort for all white-winged dove research programs in Texas. Standardized collection of reproductive information, combined with increased effort towards estimating adult survival and harvest using bandings, should allow for more informed population management of white-winged doves in the United States.
Citation:Collier, B., M. Peterson, and N. Silvy. 2008. Nest survival of white-winged doves in South Texas. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Nesting habitat of white-winged doves in urban environments of southern Texas
Journal/Year:Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies/2008
Author(s):Jeff B. Breeden | Fidel Hernandez | Nova J. Silvy | Fred E. Smeins | Jay A. Roberson
Keywords:doves | nesting habitat | urban wildlife | white-winged dove | Zenaida asiatica
Abstract:Changes in white-winged dove (Zenaida asiatica) distribution and habitat use have occurred in Texas since the 1940s. Breeding populations are now common in urban areas throughout Texas. These changes have resulted in unique challenges for monitoring populations in urban environments because of factors such as traffic, construction, and residential development. Delineating potential breeding habitat within urban areas may make surveys more efficient. Our objectives were to examine nest tree selection and identify habitat attributes associated with urban populations of white-winged doves. We conducted nest searches at 15 auditory-count survey points in Kingsville, Texas, in 2003 and documented trees used for nesting. We tested the relationship of white-winged dove density (n = 49 survey points) with associated fine-resolution (mesquite [Prosopis glandulosa] density, favorable tree density, and total tree density) and course-resolution (% mesquite canopy cover, % shade tree canopy cover, % woody plant canopy cover, and % open lawn) habitat variables throughout Kingsville in 2005. We documented that white-winged doves selected for live oak (Quercus virginiana) and against mesquite for nesting. The strongest relationships we found with fine-resolution and course-resolution habitat variables were between white-winged density and favorable tree density (R² = 0.40; P < 0.001) and % shade tree canopy cover (rR² = 0.57; P < 0.001), respectively. Densely-canopied trees such as live oak may be the best indicator of suitable nesting habitat in urban areas. These data can be useful in predicting potential white-winged dove habitat in urban areas and for refining survey protocol regarding allocation and distribution of survey effort.
Management Implications:Because white-winged doves continue to expand northward, there is a continual need to survey additional cities. Knowledge of habitat characteristics influencing dove nesting and presence provides valuable information necessary for designing efficient and effective surveys. The results from this and prior research indicate that shade trees characterized by dense foliage are an important component of white-winged dove breeding habitat in urban areas. These data can be used to develop crude habitat-suitability models to predict potential white-winged dove habitat in urban areas and thereby used to refine survey protocol regarding allocation and distribution of survey points. Therefore, surveys can be made more efficient and reliable by concentrating survey effort in areas where white-winged doves occur. Researchers also may be able to simply examine an aerial photo of an urban area and identify possible preferred habitat in which to place survey points based on presence and canopy cover of favorable nesting trees.
Citation:Breeden, J. B., F. Hernandez, N. J. Silvy, F. E. Smeins, and J. A. Roberson. 2008. Nesting habitat of white-winged doves in urban environments of southern Texas. Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 62:58-63.
Title:Abundance of wigeongrass during winter and use by herbivorous waterbirds in a Texas coastal marsh
Journal/Year:Wetlands/2009
View:Download Hartke_etal_2007_Wigeongrass.pdf
Author(s):Kevin M. Hartke|Kevin H. Kriegel|G. Matt Nelson|M. Todd Merendino
Keywords:exclosure|food availability|herbivory|Ruppia maritima|waterfowl
Abstract:Wigeongrass (Ruppia maritima), a submerged aquatic plant inhabiting estuarine wetlands, is an important winter food for waterbirds along the Texas Gulf Coast. We examined availability of wigeongrass at Mad Island Wildlife Management Area, Texas, USA by estimating aboveground biomass from October through January, 1998-1999 and 2001-2002. We also used an exclosure experiment to determine the extent to which herbivory by waterbirds was responsible for depletion of wigeongrass. Aboveground biomass of wigeongrass declined an average of 189 g/m2 and 71 g/m2 between October and January each year. Aboveground biomass declined at a higher rate among plots exposed to herbivory compared to exclosures, and the loss of biomass attributable to foraging by waterbirds was 19%. In 1998, counts of gadwalls (Anas strepera), American wigeons (A. americana), and American coots (Fulica americana) using study ponds peaked in November and then followed a declining trend similar to availability of wigeongrass, suggesting that as wigeongrass was depleted herbivorous waterbirds moved to other habitats where food was more available.
Management Implications:Coastal wetland managers concerned with providing food resources for herbivorous waterbirds should try to maintain a complex of brackish and freshwater wetlands to provide alternative sources of submerged aquatic vegetation. As availability of wigeongrass is depleted from brackish wetlands, foraging waterbirds can switch to adjacent freshwater habitats where food may be more abundant. In addition, biologists interested in modeling carrying capacity of coastal marsh as winter foraging habitat for waterbirds need to consider factors that may reduce overall availability of submerged aquatic vegetation.
Citation:Hartke, K. M., K. H. Kriegel, G. M. Nelson, and M. T. Merendino. 2009. Abundance of wigeongrass during winter and use by herbivorous waterbirds in a Texas coastal marsh. Wetlands 29:288-293.
Title:Characteristics of foraging perch-sites used by loggerhead shrikes
Journal/Year:The Wilson Journal of Ornithology/2009
View:Download Becker_etal_2009_LoggerheadShrike.pdf
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Author(s):Miles E. Becker|Peter A. Bednekoff|Michael W. Janis|Donald C. Ruthven III
Abstract:Perch-sites are a necessary component of Loggerhead Shrike (Lanius ludovicianus) foraging habitat, yet little is known about the influence of perch characteristics on perch use. We hypothesized that Loggerhead Shrikes would selectively forage from taller, bare perches with less foliar obstruction to potentially increase prey detection rates. Shrikes in our study area foraged from trees ~10% taller than those available and on dead or partially dead trees more often than expected (P = 0.005). Deciduous trees with a leafy canopy in summer were more likely to be used when bare in winter. Removing all obstacles to prey detection did not increase perch preference. Shrikes perched more often and for more total time on constructed artificial perches surrounded by dead branches (50% of used; 166 sec/territory) than on treatments with leafy branches (14%; 32 sec) or no branches (36%; 50 sec). Our results suggest trees that are more useful are those with a good view of potential prey and which also provide cover from potential attacks by predators. This study demonstrates the relevance of perch-site characteristics to Loggerhead Shrike foraging habitat and we suggest consideration for perch-site characteristics in future conservation efforts.
Management Implications:Shrikes in our study population clearly selected perches with less foliage but with at least some cover. Attempts to use artificial perches to improve shrike habitat should consider the extent of cover surrounding the perch. Artificial perches are relatively easy and inexpensive to construct, and their addition to habitat without natural perch substrate could make foraging habitat more accessible and more likely to be used by shrikes (Lynn et al. 2006) or small raptors (Sheffield et al. 2001). Other species, including American Kestrels (Falco sparverius) and larger raptors (Kim et al. 2003), may use artificial perches intended for shrikes and could increase competition or predation risk. The possible negative effects of increased perch abundance on shrike populations would be worth studying. Attention to characteristics of natural perches may also be important in Loggerhead Shrike habitat where machinery, chemicals, or fire modify the structure or abundance of available perch sites (Ansley and Castellano 2006). The influence of natural perch characteristics and introduced artificial perches on shrike densities and distribution at a larger scale than within territories warrants further research.
Citation:Becker, M. E., P. A. Bednekoff, M. W. Janis, and D. C. Ruthven, III. 2009. Characteristics of foraging perch-sites used by loggerhead shrikes. The Wilson Journal of Ornithology 121:104-111.
Title:Developing an aging criteria for hatch-year white-winged doves
Journal/Year:TPWD Final Report/2009
View:Download Fedynich_Hewitt_2009_WWDAgingCriteria.pdf
Author(s):Alan M. Fedynich|David G. Hewitt
Abstract:The white-winged dove (Zenaida asiatica) is expanding throughout much of the southern United States (Schwertner et al., 2002). Consequently, research is being directed toward understanding the ecology of this species, particularly in view of its status as a migratory game bird (George et al., 2000). To aid researchers and biologists in determining population characteristics, it is often necessary to assign individuals into age classes. Unfortunately, there is little information regarding how to accurately determine the specific age of hatch-year (HY) white-winged doves as they transition into adults. This study will characterize feather development, persistence of immature secondary coverts, and primary feather replacement in captive HY white-winged doves.
Citation:Fedynich, A. M., and D. G. Hewitt. 2009. Developing an aging criteria for hatch-year white-winged doves. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Effects of grassland restoration on avian assemblage characteristics and dickcissel nesting success in Texas
Journal/Year:Thesis/2009
View:Download Lituma_2009_GrasslandRestoration.pdf
Author(s):Christopher M. Lituma
Abstract:The prairies of North America have undergone substantial changes since European settlement in the 1800's, with some estimates suggesting that 96% of the tallgrass prairie has been converted. Multiple factors contributed to reduction in prairie, including: grazing, row-crop farming, depressed fire regimes, and exotic grass species introduction. In Texas, 35% of the historic grassland ecosystems have been either altered or converted. Introduced in the 1940's, exotic grass species such as Bermuda grass (Cynodon sp) have displaced native grass species throughout Texas. Introduced grass species can alter the existing plant communities degrading habitat for birds and other animals. Grassland birds are declining faster than any other bird group within North America; due in part to a reduction in suitable breeding habitat. I addressed this issue by comparing nesting success of grassland birds between exotic grass sites and restored native grass sites in the blackland prairie region of east-central Texas during 2007-2008 breeding seasons. I conducted point counts and nest searching from March - July. Point count data indicate no difference in species richness between sites. Dickcissel (Spiza americana) nests represented 89% of the nests found (n = 104). Dickcissel abundance was 44% higher in restored sites and 76% of nests were located in restored sites. Daily survival (DSR) for dickcissels in restored sites was 0.895 (SE = 0.013) and for exotic sites was 0.930 (SE = 0.017). I used an independent samples t-test to compare mean nest height, which was 56% higher in restored sites than exotic sites (n = 83, = 38.0 cm ± 1.90; = 15.2 cm ± 2.19, df = 81, t = -6.31, P = 0.001), and mean nest substrate height which was 58% higher in restored sites than in exotic sites (n = 83, = 118.8 cm ± 6.50; = 46.5 cm ± 4.77, df = 81, t = -6.08, P = 0.001). Although dickcissel abundance was greater in restored sites than exotic sites, their observed nesting success and DSR was lower in restored sites. This is indicative of an ecological trap, which occurs when an organism is attracted to a habitat that negatively impacts the organism. Some research suggests that restored fields in other states are acting as traps for dickcissels, and according to my results restored sites I sampled may also be acting as ecological traps for dickcissels in Texas.
Management Implications:Continued research in the blackland prairie region of Texas should focus on the predator community. Though I did not identify predators for this study because of logistical constraints, I noted signs of predation and the majority of predatory signs suggest that snakes are the main predator in this area. Snakes are a common predator of many passerines including dickcissels (Pietz and Granfors 2000, Renfrew and Ribic 2003, Stake et al. 2005). These restored areas are attracting large numbers of dickcissels, which are potentially attracting predators. Dickcissels were among the most abundant bird species detected on all sites, and this is likely another reason for high depredation. My research provides information suggesting more dickcissel nests fledged in restored areas than in exotic areas, despite a lower DSR and observed success. According to my research prairie restorations in Texas are positively impacting the dickcissel. Further research is needed to definitively state what the cause for high predation rates in this area is, and to more accurately assess the predator community (Vickery and Herkert 2001, Renfrew and Ribic 2003, Weatherhead and Blouin-Demers 2004, Fletcher et al. 2006).
Citation:Lituma, C. M. 2009. Effects of grassland restoration on avian assemblage characteristics and dickcissel nesting success in Texas. Thesis, Texas A&M University, College Station, USA.
Title:Foraging ecology of migrant shorebirds in saline lakes of the Southern Great Plains
Journal/Year:Waterbirds/2009
View:Download Andrei_etal_2009_ForagingEcologyShorebirds.pdf
Author(s):Adrian E. Andrei|Loren M. Smith|David A. Haukos|J. G. Surles|William P. Johnson
Keywords:American Avocet|invertebrates|Least Sandpiper|Lesser Yellowlegs|migration stopovers|Ogallala aquifer|saline lakes|shorebirds|Southern Great Plains|Wilson's Phalarope
Abstract:Tens of thousands of shorebirds use saline lakes as migratory stopovers in the Southern Great Plains, USA. To assess their foraging strategies and understand how they replenish energy reserves during spring and summer/fall migrations, we examined diets, prey taxa selection, and prey size selection of American Avocets (Recurvirostra americana), Least Sandpipers (Calidris minutilla), Wilson's Phalaropes (Phalaropus tricolor), and Lesser Yellowlegs (Tringa flavipes). Migrant shorebirds foraged opportunistically by taking most prey taxa according to their availability. Least Sandpipers preferred small prey (2-5 mm), whereas American Avocet, Wilson's Phalaropes, and Lesser Yellowlegs generally preferred intermediate and large prey (6-20 mm). By consuming prey taxa according to their availability and prey sizes that require minimum energy to capture and ingest, shorebirds increase their ability to replenish energy reserves while migrating through interior North America. Drought and drying of freshwater springs will reduce availability of prey in saline lakes for migrating shorebirds. To preserve the saline lakes as important habitats where shorebirds replenish nutrient reserves while migrating through the Great Plains, it is important to conserve groundwater so that freshwater springs continue to discharge into the lakes.
Management Implications:Declining water tables, reduced freshwater spring flow, and increased salinity could reduce the importance of saline lakes in the SGP as migration stopovers because the foraging strategies used by shorebirds may become ineffective due to reduced availability of invertebrates. For most saline lakes, water management and moist-soil management are not possible. Managers and conservationists should focus on preserving water and low salinities. Thus, it is important to conserve the Ogallala aquifer and the freshwater springs discharging into saline lakes, especially during dry years. Because the Ogallala aquifer is recharged through playa wetlands (Osterkamp and Wood 1987; Nativ 1992; Smith 2003), the entire complex of wetlands in the SGP should be protected by reducing groundwater withdrawals (Triplet 1998; Sophocleous 2000) and by preventing sedimentation in playas, which may influence recharge (Luo et al. 1997).
Citation:Andrei, A. E., L. M. Smith, D. A. Haukos, J. G. Surles, and W. P. Johnson. 2009. Foraging ecology of migrant shorebirds in saline lakes of the Southern Great Plains. Waterbirds 32:138-148.
Title:Grassland bird associations with introduced and native grass conservation reserve program fields in the southern High Plains
Journal/Year:Western North American Naturalist/2009
View:Visit BioOne - Grassland bird associations with introduced and native grass conservation reserve program fields in the southern High Plains
Author(s):Thomas R. Thompson|Clint W. Boal|Duane Lucia
Keywords:Ammodramus savannarum|Aimophila cassinii|Cassin's sparrow|conservation reserve program|Eremophila alpestris|Grasshopper sparrow|horned lark|Passerculus sandwichensis|Savannah sparrow|Sturnella neglecta|Western meadowlark
Abstract:We examined relative abundances of grassland birds among Conservation Reserve Program (CRP) fields seeded with 2 monocultures of introduced grass species and 2 mixes of native grasses in the Southern High Plains of Texas. We assessed bird compositions among these 4 cover types and between the cover types pooled into categories of introduced and native fields. Breeding season bird diversity and total abundance did not differ among cover types or between introduced and native fields. Grasshopper Sparrows (Ammodramus savannarum), Cassin's Sparrows (Aimophila cassinii), and Western Meadowlarks (Sturnella neglecta) accounted for more than 90% of breeding season detections. Grasshopper Sparrows were the most abundant and found in all cover types. Cassin's Sparrows were 38% to 170% more abundant among the native seed mix without buffalograss (Buchloe dactyloides) compared to 3 other cover types. Although this association was statistically lost when cover types were pooled into introduced or native fields (U = 93.5, P = 0.91), the species was still 50% more abundant among native CRP than introduced CRP fields. Meadowlarks occurred ubiquitously but at very low numbers during the breeding season. During winter, avian abundance was 44% greater among native CRP than introduced CRP fields. Meadowlarks, Horned Larks (Eremophila alpestris), and Savannah Sparrows (Passerculus sandwichensis) accounted for 94% of all winter detections. Meadowlarks occurred ubiquitously, but Horned Larks and Savannah Sparrows were 157% and 96% more abundant, respectively, among native CRP than introduced CRP fields. Our data suggest that monocultures of introduced grasses may benefit some bird species but also that native seed mixes may have a more positive influence through increased diversity and abundance of grassland birds. However, pooling cover types into the broader categories of introduced or native grasses may dampen or occlude biologically meaningful results. It may be prudent to avoid broad categorization of CRP fields based solely on native or introduced grass cover when assessing habitat associations of grassland birds.
Management Implications:An important point regarding our data on Cassin's Sparrows concerns resolution of habitat types. Although Cassin's Sparrows were more abundant in native-A fields, the ability to discern their association with heterogeneous mixes of native species was lost when cover types were pooled into the coarser categories of introduced or native field types. Thus assessment of Cassin's Sparrow use of CRP fields, and perhaps use by other grassland species, may require examination at finer resolutions than the broad categories of introduced or native field types. Our data suggest that no one seeding type is most attractive to grassland passerines in general but that CRP fields function as an important conservation tool. Similar to our study, other researchers found that CRP fields planted with mixtures of native grasses promoted increased avian abundance, diversity, use, and production compared to monocultures of introduced grass (Delisle and Savidge 1997, Davis and Duncan 1999, McCoy et al. 2001). In comparison to introduced monocultures, native seed mixes on CRP fields may have more positive influences for grassland birds. Pooling of cover types into the broader categories of introduced or native grasses risks dampening or occluding biologically meaningful results in characterizing vegetative characteristics or avian abundances in CRP fields of different grass compositions. For this reason, it would be prudent to avoid broad categorization of CRP lands as only introduced or native fields when assessing the value of different CRP field cover types.
Citation:Thompson, T. R., C. W. Boal, and D. Lucia. 2009. Grassland bird associations with introduced and native grass conservation reserve program fields in the southern High Plains. Western North American Naturalist 69:481-490.
Title:Habitat characteristics of winter roost sites of wild turkeys in Trans-Pecos, Texas
Journal/Year:The Southwestern Naturalist/2009
View:Download erlicheck_etal_2009_TurkeyRoost.pdf
Author(s):Kory B. Perlichek|Louis A. Harveson|Bonnie J. Warnock|Billy Tarrant
Abstract:Wild turkeys (Meleagris gallopavo) occur intermittently throughout Trans-Pecos, Texas. In the lower desert of the Trans-Pecos, turkeys are associated strongly with the limited riparian habitat where roosting habitat is found. We initiated a study to document microhabitat characteristics of roost sites in the Trans-Pecos region of Texas. We measured microhabitat characteristics (canopy cover, density of stand, visual obstruction, understory herbaceous cover, height of tree, diameter at breast height (dbh), height-to-lowest live branch, slope, and aspect) at 15 winter roosts and 15 random sites in three habitats in the Trans-Pecos region: ponderosa pine (Pinus ponderosa), live oak (Quercus virginiana), and sugar hackberry (Celtis laevigata). All roost sites were < 1 km from riparian corridors and located in riparian regions. Among the three habitats, large diameters and height of trees were a prerequisite for roost trees in live oak and sugar hackberry habitat, where live oaks used as roost trees were larger (mean dbh = 57.78 cm) than non-roosting trees (mean dbh = 39.13 cm). Roost trees in live oak habitat had a greater height than trees in random sites (13.58 and 11.28 m, respectively). Sugar hackberries used as roost trees had larger dbh, height, height-to-lowest live branch, and canopy cover than nonroost trees in random sites. Due to the sparse density of trees, we recommend that riparian corridors with potential roosting habitat be protected throughout the Trans-Pecos. In addition, exotic species (e.g. Tamarisk) should be controlled and native riparian habitats should be preserved.
Management Implications:In our study, all roost sites in winter were in canyons and swales along riparian corridors in the Trans-Pecos region. Riparian areas are critical habitat for wild turkeys, especially for roosting. Roosting habitat has declined throughout Texas because of changing weather patterns, invasion of exotic plants (e.g. Tamarisk), and overgrazing in riparian areas. Data provided herein serves as a baseline inventory of roosting habitat of wild turkeys west of the Pecos River. Based on our results, we recommend that wildlife managers, as well as private landowners, preserve, manage, and reestablish riparian corridors through reseeding, fencing, and conservative grazing.
Citation:Perlichek, K. B., L. A. Harveson, B. J. Warnock, and B. Tarrant. 2009. Habitat characteristics of winter roost sites of wild turkeys in Trans-Pecos, Texas. The Southwestern Naturalist 54:446-452.
Title:Habitat suitability model for evaluating city of San Antonio land donation for golden-cheeked warblers
Journal/Year:TPWD Final Report/2009
View:Download Heilbrun_2009_GCWSanAntonio.pdf
Author(s):Richard Heilbrun|Allison Arnold|Niki Lake|Deirdre Hisler
Abstract:The Golden-cheeked warbler (Dendroica chrysoparia; hereafter GCWA) is a federally and state listed endangered species that nests and rears its young exclusively in the Edwards Plateau ecoregion of central Texas. The species is listed in the Texas Wildlife Action Plan as a high priority species that is critically imperiled. The City of San Antonio (COSA) passed bond measures in 2000 and 2005 to protect land over the Edwards Aquifer, the city's primary source for drinking water. In the summer of 2008, COSA initiated discussions with TPWD to transfer 2,980 acres to TPWD to provide public access and to increase endangered species protection, vegetation management, and monitoring. Prior to the acceptance of these parcels, TPWD conducted an assessment of the properties for potential golden-cheeked warbler habitat. Given time, personnel, and financial constraints, it was necessary to develop a new methodology that would allow comparison to nearby Camp Bullis (US Army) and meet USFWS standards of documenting potential or occupied habitat for the GCWA. This study created a point-based GIS model informed by field-collected vegetation data to 1) describe vegetative characteristics of the study area, 2) Evaluate the study area for potential golden-cheeked warbler habitat, and 3) collect incidental locations of Golden-cheeked warblers on the property. To evaluate similarity to TPWD habitat guidelines for the GCWA (Campbell 1995), we collected vegetation data including canopy height, canopy closure, species diversity, age and size of Ashe Juniper, and qualitative measures of deciduous components. We established 2 sets of at least 300 points over nearly 3,000 acres of potential GCWA habitat. Survey parcels were adjacent to the 8,600-acre Government Canyon State Natural Area (TPWD). Each set was surveyed independently and at least 5 days apart from the other set. We recorded 157 observations of GCWA throughout the study area. Using a nearest neighbor interpolation, we present field based coverage layers for each vegetation characteristic. Using these coverages, we estimate that 76.8% of the study area is potential GCWA habitat. We analyzed GCWA locations by vegetation characteristics to test the model. Approximately 79% of GCWA observations were within the spatial boundaries of our predictive model. 81% of GCWA observations were found where canopy closure ≥ 35%. 93% of observations were made where Juniper comprised 10-90% of the canopy, and 83% of observations were in canopy ≥ 20 ft. This approach was useful in evaluating habitat for GCWA while simultaneously performing presence surveys acceptable to USFWS. When project timelines do not facilitate multi-year protocol surveys, this approach, slightly modified, will be useful in delineating potential habitat for Golden-cheeked warblers. Our method can be completed within 1 breeding season, by non-technical personnel, and provides useful data on habitat selection within Bexar County. With this vegetation data, this approach will allow us to formulate standardized habitat definitions for Bexar County, and determine whether habitat preferences differ throughout the breeding range of the GCWA. Such knowledge will be useful in regional land planning, landowner education and outreach, and long term recovery of this endangered species.
Management Implications:This approach was useful in evaluating habitat for GCWA while simultaneously performing presence/absence surveys. When project timelines do not facilitate multi-year protocol surveys, this approach will be useful in delineating potential habitat for Golden-cheeked warblers. While our methods are labor intensive, they can be completed within 1 breeding season, and provides useful data on habitat selection within Bexar County. With this vegetation data, this approach will allow us to formulate standardized habitat definitions for Bexar County, which will be useful in regional land planning, landowner education and outreach, and long term recovery of this endangered species. Additional data would also help refine and test our model parameters. We recommend that GCWA protocol surveys be conducted on this study area in future years to assess and refine model strength. We also recommend that this method be used to evaluate new properties to simultaneously collect more data on localized habitat selection and perform presence/absence surveys. We recommend small modifications to survey methods, which should strengthen the model. Field crews should record 4 canopy closure readings at each survey point, 1 in each cardinal direction. The age classification of junipers was useful in comparing this study area to Camp Bullis data, but we recommend additional sub-categories denoting when Junipers are >15ft, >5" dbh, and whether they have stripping bark. Additionally, our time requirements and survey methods did not facilitate the development of a complete floristic inventory. We recommend these data to be collected as additional species are encountered between points.
Citation:Heilbrun, R., A. Arnold, N. Lake, and Deirdre Hisler. 2009. Habitat suitability model for evaluating city of San Antonio land donation for golden-cheeked warblers. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Impact of red imported fire ants on insect abundance as a food source for broods of the critically endangered Attwater's prairie-chicken
Journal/Year:TPWD Final Report/2009
View:Download Calixto_etal_2009_FireAntsAPC.pdf
Author(s):Alejandro A. Calixto|Bart Drees|Mike Morrow|Donna Roach|Johnny Johnson
Management Implications:This preliminary study failed to document consistent and significant impacts of RIFA foraging on insects and other arthropods with the exception that numbers of pill bugs (Isoptera) were significantly higher and larger (mm) in RIFA reduced plots. It is possible that the study design for this preliminary study was inadequate to determine impacts on arthropod communities, especially with respect to duration of RIFA reduction as it relates to the life history of other arthropods. Because of the preliminary nature of this study, plot size and number of replications may have been inadequate to document effects of RIFA control. Additionally, factors other than RIFA (e.g., weather, poor drainage, genetic isolation, pesticide drift, etc.) may have contributed to low insect/arthropod abundance in this area. A more elaborate study that accounts for these design constraints should be considered for future efforts. Classification to lower taxonomic levels may be necessary for understanding RIFA impacts. RIFA and insect/arthropod assessments through the year, particularly in late fall and early spring, could perhaps better document the relationship between these groups and timing of RIFA reduction and subsequent re-invasion. Finally, the development of target-specific treatments for RIFA, particularly in areas where RIFA population densities are low in order to assure minimization of potential secondary impacts of insecticide baits on non-target species, would possibly improve the likelihood of documenting the effects of RIFA on local insect/arthropod assemblages and support implementation of RIFA as a management practice in this sensitive environment.
Citation:Calixto, A. A., B. Drees, M. Morrow, D. Roach, and J. Johnson. 2009. Impact of red imported fire ants on insect abundance as a food source for broods of the critically endangered Attwater's prairie-chicken. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Intra-annual variation in white-winged dove density in the Texas hill country
Journal/Year:Bulletin of the Texas Ornithological Society/2009
View:Download Small_etal_2009_WWDDensity.pdf
Author(s):Michael F. Small|John T. Baccus| Jay A. Roberson
Abstract:White-winged Dove populations in Texas have extended their range over the past 50 years. Concurrent with this range expansion has been the establishment of new, urban populations which usually include some proportion of non-migratory residents. We conducted distance sampling point counts for White-winged Doves on 17 occasions between February 2006 and February 2007. We obtained White-winged Dove density estimates for all 17 distance sampling occasions. In addition we trapped and banded White-winged Doves from January through August 2006 and recorded ages (hatching year or after hatching year). Winter population size was about 30% smaller than summer peak population size. The peak in summer population size also corresponds strongly with peak numbers of HY captures, indicating population growth is most likely the result of reproductive recruitment and not immigration.
Management Implications:Our study demonstrates that important demographic and natural history information can be effectively obtained for urban White-winged Dove populations. Additional testing should be conducted to determine the degree of bias (if any) present in sampling from roads as opposed to completely random sampling. Also, further research to determine whether proportions of migratory to resident White-winged Doves vary temporally and spatially is still required. Additionally, there is no information on whether the same individuals comprise the resident winter population over time or what factors (i.e., individual age, gender) influence winter populations. Until a more complete understanding of White-winged Dove populations in Texas is reached, fully informed management and policy decisions regarding this unique species can not be made.
Citation:Small, M. F., J. T. Baccus, and J. A. Roberson. 2009. Intra-annual variation in white-winged dove density in the Texas hill country. Bulletin of the Texas Ornithological Society 42:56-61.
Title:Recovery of the golden-cheeked warbler
Journal/Year:TPWD Final Report/2009
View:Download Morrison_etal_2009_GCWRecovery.pdf
Author(s):Michael Morrison|Bret Collier|Neal Wilkins|Brian Hays
Abstract:The activities in this final report were coordinated with the ongoing Fort Hood off-site Conservation Project (FHOSCP). Funding from Texas Parks and Wildlife directly supported data collection. The overall goal of our work is to contribute to the environmental management goals of Fort Hood through participation in an off-site conservation program. Included are reports focused on three main sections: 1.) Distribution and Abundance of Golden-cheeked Warblers on Private Lands, 2.) Investigating Habitat Use, Habitat Selection, Reproductive Success, and Potential Factors Affecting Reproductive Success of Golden-cheeked Warblers, and 3.) Outcomes and Outreach. Activities under these projects were initiated in Fiscal Year 2005 and have continued through 2009.
Citation:Morrison, M., B. Collier, N. Wilkins, B. Hays, J. Butcher, S. Farrell, A. Campomizzi, T. Pope, and T. Conkling. 2009. Recovery of the golden-cheeked warbler. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Status of white-winged dove nesting colonies in Tamaulipas, Mexico
Journal/Year:The Wilson Journal of Ornithology/2009
View:Download SanchezJohnson_etal_2009_WWDMexico.pdf
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Author(s):Yara Sanchez Johnson|Fidel Hernandez|David G. Hewitt|Eric J. Redeker|Gary L. Waggerman|Heriberto Ortega Melendez|Hector V. Zamora Trevino|Jay A. Roberson
Abstract:The core of eastern White-winged Dove (Zenaida asiatica asiatica) breeding habitat historically occurred in northern Mexico and southern Texas. Much nesting-habitat loss has occurred in this region since the mid-1990s and several large nesting colonies of the historic complex have disappeared with others currently at risk. Little knowledge exists regarding the precise location of these colonies or their current status. We reviewed the literature, interviewed biologists, and conducted site visits to Tamaulipas, Mexico during May-August 2004 and 2005 to construct a historical account of White-winged Dove colonies. We found references to 77 possible nesting colonies thought to exist over a 50-year period in Tamaulipas. However, 26 references represented alternative names for the same colonies resulting in 51 colonies. We located 31 of these colonies of which 13 were active and 18 were inactive. The remaining 20 were not described in sufficient detail to locate. Brush clearing was listed as a cause for 78% of the 18 inactive colonies followed by weather catastrophes (56%) and overharvest (39%). Collectively, these 3 factors appeared to be responsible for 94% of all colony loss. The historic, large colonies of the past are gone and likely will not return because of these factors, primarily because of brush clearing.
Management Implications:We encountered numerous obstacles in reconstructing the historical account for the Tamaulipan colonies despite the meritorious work of early biologists. Numerous colonies had duplicate or alternative names and descriptions of some colony locations were not sufficient to permit relocation. Differences in monitoring methodologies complicated data compilation and interpretation. We recommend that current monitoring studies and data collection protocols be refined to prevent further confusion. Continued cooperation between the Mexican and USA governments is fundamental to protect the remaining White-winged Dove nesting areas in Tamaulipas given the loss of historic nesting colonies and continued clearing of nesting habitat.
Citation:Sanchez Johnson, Y., F. Hernandez, D. G. Hewitt, E. J. Redeker, G. L. Waggerman, H. Ortega Melendez, H. V. Zamora Trevino, and J. A. Roberson. 2009. Status of white-winged dove nesting colonies in Tamaulipas, Mexico. The Wilson Journal of Ornithology 121:338-346.
Title:Texas bald eagles
Journal/Year:Bulletin of the Texas Ornithological Society/2009
View:Download Ortego_etal_2009_TXEagles.pdf
Author(s):Brent Ortego|Chris Gregory|David Mabie|Mark Mitchell|Dale Schmidt
Abstract:Bald Eagles (Haliaetus leucocephalus) were studied in Texas from 1970 to 2009 by the Texas Parks and Wildlife Department. Active nests increased from 5 in 1970 to 156 in 2005 when the last aerial survey was conducted. A total of 547 nest sites in 313 territories in 76 counties were identified thru May 2009. Longevity of 261 nests tracked averaged 4.2 years with a standard deviation of 3.4. Six hundred and sixty-one food items were examined at nest sites. They were comprised of 33.7% birds, 30.7% reptiles and 30% fish. Hurricanes did not appear to have any impacts on nest production. Nest production varied from 1.2 to 1.45 young per active nest. One-hundred and thirty-eight eaglets were banded and color-marked. Fledging success was 97% after 6 weeks of age. Three band recoveries and sightings of 29 adults and 32 immatures were obtained. Twenty sightings occurred outside of Texas with 74% of these occurring from May to August. Texas born eagles were reported from South Carolina to Canada and Arizona. Bald Eagle populations are increasing 13% per year, but there are a number of threats which may limit populations in the future.
Citation:Ortego, B., C. Gregory, D. Mabie, M. Mitchell, and D. Schmidt. 2009. Texas bald eagles. Bulletin of the Texas Ornithological Society 42:1-17.
Title:The ecological implications of marsh management to wetland birds
Journal/Year:TPWD Final Report/2009
View:Download Fitzsimmons_etal_2009_MarshManagementReport.pdf
Author(s):Owen N. Fitzsimmons|Bart M. Ballard|M. Todd Merendino|Kevin M. Hartke
Citation:Fitzsimmons, O. N., B. M. Ballard, M. T. Merendino, and K. M. Hartke. 2009. The ecological implications of marsh management to wetland birds. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Toward increasing avian diversity: urban wildscapes programs
Journal/Year:Urban Ecosystems/2009
View:Visit Springer - Toward increasing avian diversity: urban wildscapes programs
Author(s):Amanda L. Aurora|Thomas R. Simpson|Michael F. Small|Kelly C. Bender
Keywords:avian diversity|urban|wildscapes|neighborhood
Abstract:Residential development in urban and suburban settings is a major cause of habitat change affecting avian communities. The effects from land-clearing prior to initiation of construction, followed by landscaping focused on traditional aesthetics, has reduced habitat diversity at multiple levels. These residential developments generally emphasize the use of ornamental, nonindigenous vegetation with little to no concern for native species and natural vegetation parameters. As a result, avian community composition and diversity is changed. We compared avian communities at three sites in Bexar County, Texas; two residential neighborhoods in the city of San Antonio and an unincorporated undeveloped site, Government Canyon State Natural Area. The residential neighborhoods were a Texas Parks and Wildlife Department certified wildscapes development and a traditionally developed neighborhood. Bird abundance and species richness in the neighborhoods were greater than at Government Canyon State Natural Area (P < 0.01), but no differences existed between the neighborhoods. Bird diversity was greatest at the wildscapes neighborhood (P < 0.01). Further, bird diversity did not differ between the traditional neighborhood and the natural area. Evenness differed among sites (P = 0.006) with the natural area having the greatest value. Bird diversity measures correlated with woody plant density and vertical cover (r = 0.358 to 0.673, P < 0.05) at residential sites. Residential areas incorporating natural landscapes into their design attracted a greater variety of birds than traditionally landscaped residential areas.
Management Implications:Our results are consistent with research linking urban and suburban development and the intermediate disturbance hypothesis (Blair 1996, Marzluff 2005, McKinney 2002). McKinney (2002) suggests the most efficient conservation strategy for maintaining species richness within housing developments is to retain predevelopment vegetation. This practice, incorporated in development of WCN, represents an intermediate stage of neighborhood development compared to traditional construction techniques which remove existing vegetation to facilitate construction. Since completion of our study, five additional neighborhoods have been certified as Texas Wildscapes. Additional studies are needed to evaluate overall program effectiveness, but our study indicates the Texas Wildscapes program and similar programs have the potential to provide significant benefits to native wildlife species in residential areas.
Citation:Aurora, A. L., T. R. Simpson, M. F. Small, and K. C. Bender. 2009. Toward increasing avian diversity: urban wildscapes programs. Urban Ecosystems 12:347-358.
Title:Winter time-activity budgets of diving ducks on eastern Texas reservoirs
Journal/Year:Waterbirds/2009
View:Download Crook_etal_2009_DivingDucks.pdf
Author(s):Shaun L. Crook|Warren C. Conway|Corey D. Mason|Kevin J. Kraai
Keywords:Aythya|Canvasback|east Texas|Lesser Scaup|Ring-necked Duck|time-activity budgets|reservoirs|waterfowl behavior|wintering waterfowl
Abstract:Wintering diving duck (Aythya spp.) time-activity budgets have been developed for many species in different regions. As such, direct comparisons can be made among studies where substantial deviations in "normal" activity budgets can provide insight as to how location, food resources, habitat, weather and human disturbance may differentially influence behavior(s) during winter. To examine how diving ducks use large reservoirs in eastern Texas, 1,275 individual time-activity budgets were quantified for Canvasback (Aythya valisineria), Lesser Scaup (A. affinis) and Ring-necked Duck (A. collaris) wintering on B.A. Steinhagen, Sam Rayburn and Toledo Bend Reservoirs during winter 2003/2004 and 2004/2005. Behaviors varied among species (P < 0.001), where food acquisition, locomotion and resting-related behaviors dominated time-activity budgets. All three species spent similar time feeding compared to other studies in the southeastern United States, but spent substantially more time locomoting than previously reported. Human disturbances from boat traffic were associated with time spent locomoting, but no species dramatically increased time feeding to compensate for increased time locomoting. Wintering diving duck activity budgets on these large eastern Texas reservoirs were generally similar to previous studies in the southeast. However, the (in)direct impacts of boat disturbances warrants closer investigation, specifically related to wintering waterfowl responses and the potential utility or value of voluntary avoidance areas during winter.
Citation:Crook, S. L., W. C. Conway, C. D. Mason, and K. J. Kraai. 2009. Winter time-activity of diving ducks on eastern Texas reservoirs. Waterbirds 32:548-558.
Title:Assessment of metal concentrations and uptake in waterfowl food items from a treatment wetland
Journal/Year:TPWD Final Report/2010
View:Download Comer_Ford_2010_MetalConcentrations.pdf
Author(s):Christopher E. Comer|Holly M. Ford
Abstract:As part of a 2003 cooperative agreement, Tarrant Regional Water District (TRWD) and Texas Parks and Wildlife Department (TPWD) are building and maintaining over a thousand acres of treatment wetlands on Richland Creek Wildlife Management Area (RCWMA) to treat water from the Trinity River before discharge into Richland Chambers Reservoir. This project represents a unique partnership that combines improving water quality and supply with meeting the needs of wildlife and wildlife enthusiasts. These wetlands are managed for wintering waterfowl use and to provide public hunting opportunities. As a pilot phase test of the system, four wetland cells were constructed in 2003-4 to evaluate treatment efficiency and waterfowl use. Because the Trinity River contains elevated concentrations of certain contaminants, specifically the heavy metals arsenic, mercury, and lead, TPWD was concerned about health risks to waterfowl using the wetlands and hunters consuming waterfowl from the area. To address these concerns, we initiated a research project to determine concentrations of As, Hg, and Pb in waterfowl food items in the wetland cells and evaluate potential ecotoxicological risks to waterfowl at the site. We sampled potential exposure pathways at 10 randomly located sites in each of the four wetland cells and at 2 reference wetlands that did not receive pumped water from the Trinity River. At each location, we sampled seeds commonly consumed by waterfowl (Echinochloa sp. and Polygonum sp.), tubers of plants consumed by waterfowl (Sagittaria sp.), and foliage of aquatic plants consumed by certain species (Ceratophyllum demersum). We also sampled sediment for incidental exposure and both benthic and water column invertebrates and compared concentrations of contaminants to published toxicity reference values to evaluate ecological risk. Furthermore, we evaluated uptake of contaminants of concern by Echinochloa crusgallii in a controlled laboratory study using known concentrations of Hg and Pb. Plants were grown to seed production in a growth chamber and various plant parts (e.g., seeds, foliage, and roots) harvested to measure uptake. Risks to waterfowl and presumably other wildlife using the constructed wetland cells at RCWMA appear to be low. Concentrations of arsenic, lead, and mercury were all below relevant toxicity reference values in all media. Furthermore, we did not see a consistent pattern where any of the contaminants of concern were elevated in wetland cells compared to background areas that did not receive input water from the Trinity River. Mercury tended to be higher in plant tissue from the background marsh area than in the wetland cells for all plants tested. Arsenic was elevated in sediments from wetland cells compared to background; however, this did not translate to elevated arsenic in the waterfowl food items. Lead concentration in treatment wetlands was similar to reference marshes. The growth chamber experiment suggested that both lead and mercury are taken up from wetland soils by barnyard grass. The uptake kinetics are not clear at this time, but it appears that uptake rates decline as the soil concentration increases. This is consistent with the presence of a threshold beyond which additional metal is not absorbed by the plant and may help mitigate against accumulation of harmful lead or mercury levels in these common waterfowl food plants. Further study will be necessary to fully describe uptake and partitioning in wetland plants. This project helps to mitigate concerns regarding uptake of heavy metals in the treatment wetlands at RCWMA. Despite high concentrations of metals in input water, waterfowl food items did not accumulate sufficient arsenic, mercury, or lead to present significant risks to waterfowl. Based on our growth chamber study, this may reflect an uptake threshold in at least some of the relevant plants. Further monitoring will be necessary as the wetland cells mature, but current risks appear to be minimal and both TPWD and TRWD should proceed with this innovative and highly successful partnership.
Citation:Comer, C. E., and H. M. Ford. 2010. Assessment of metal concentrations and uptake in waterfowl food items from a treatment wetland. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Band recovery and harvest data suggest additional American black duck records from Texas
Journal/Year:Bulletin of the Texas Ornithological Society/2010
View:Download Johnson_Garrettson_2010_BlackDucksPublished.pdf
Author(s):William P. Johnson|Pamela R. Garrettson
Abstract:We reviewed band recovery data and Cooperative Waterfowl Parts Collection Survey (PCS) data for records of American Black Ducks (Anas rubripes) shot in Texas. The PCS is an annual U.S. Fish and Wildlife Service (USFWS) survey of waterfowl harvest composition that relies on duck wings from a random sample of hunters. Between 1914 and 2009, 43 banded American Black Ducks were recovered in Texas; 74% of these recoveries involved American Black Ducks banded within their breeding range. Between the 1970-71 waterfowl hunting season and the 2008-2009 season, wings of 35 Texas harvested American Black Ducks were submitted to the PCS. For both data sets, over 50% of the records were associated with the Coastal Prairies.
Citation:Johnson, W. P., and P. R. Garrettson. 2010. Band recovery and harvest data suggest additional American black duck records from Texas. Bulletin of the Texas Ornithological Society 43:34-40.
Title:Capture rates of shorebirds at managed and riverine freshwater wetlands near the central Texas coast
Journal/Year:TPWD Final Report/2010
View:Download Ortego_ShorebirdCapture.pdf
Author(s):Brent Ortego
Abstract:Shorebirds were mist-netted at 500-ha of moist soil units (MSU) and at a 400-ha riverine overflow basin (NW) near the central Texas Coast from 1996-2001. A total of 3745 shorebirds of 24 species were captured at the MSU at a rate of 76 birds per trip. A total of 1543 shorebirds from 18 species were captured at the NW at a rate of 106 birds per trip. Least Sandpiper (Calidris minutilla), Semipalmated Sandpiper (Calidris pusilla), Western Sandpiper (Calidris mauri), Dunlin (Calidris alpina), and Stilt Sandpiper (Calidris himantopus) were the most abundant species banded at the MSU and they were recaptured at the rate of 2.6, 0.8, 0.5, 3.3, and 0.8 percent, respectively, during years following banding. Least Sandpiper, Semipalmated Sandpiper, Western Sandpiper and Stilt Sandpiper were captured most frequently at the NW and only two individuals were recaptured during years following banding. Banded birds from this study site were also captured in Nebraska for Least Sandpiper, Ecuador for Semipalmated Sandpiper, and Alaska, British Columbia and Washington for Western Sandpiper. More shorebirds were banded at the MSU site during spring and at the NW during late summer/early fall.
Management Implications:Availability of both of these habitat types are very important for conservation of migrating shorebirds near the Texas Coast because of the seasons at which they occur.
Citation:Ortego, B. 2010. Capture rates of shorebirds at managed and riverine freshwater wetlands near the central Texas coast. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Combining gobble counts, infrared camera surveys, and GIS to improve survey accuracy, estimate metapopulation size, and evaluate habitat use of eastern wild turkeys in east Texas
Journal/Year:TPWD Final Report/2010
View:Download Conway_Bass_2010_EasternWildTurkey_FinalReport.pdf
Author(s):Warren C. Conway|James Ryan Bass
Abstract:Historically, wild turkeys (Meleagris gallopavo) were found throughout the southeastern United States, including much of East Texas. However, localized overharvesting combined with alterations in land use practices, resulting in unsuitable turkey habitat, forced remaining populations to become concentrated and scarce throughout its North American range. In East Texas, the eastern subspecies (M. g. silvestris) was the endemic turkey, but by the 1940s, fewer than 100 turkeys remained. Between 1978 and 2004, 7,155 eastern wild turkeys were stocked at > 300 sites in 58 East Texas counties, but anecdotal evidence suggested that some local populations established during the restoration efforts have failed to expand or have gone locally extinct. Population estimates calculated by TPWD field staff in 2005 suggested a total Eastern wild turkey population of < 10,000, representing little change from the total number of translocated birds. To examine the utility of gobble count surveys for detecting turkeys in eastern Texas, during 2006-2008, existing East Texas gobble count route surveys were conducted, 22 male Eastern wild turkeys were captured in the Angelina National Forest, radio marked, and relocated through spring and summer each year, and field-habitat data were incorporated into a Geographic Information System (GIS) to build a predictive model for identification of optimal gobble count route placement throughout East Texas based upon model generated data. Spring (March-May 2006 and 2007) and annual (i.e., 2006 and 2007) 95% adaptive kernel home range estimates and habitat use of 22 (16 adult, 6 juvenile) wild captured and 7 translocated juvenile male Eastern wild turkeys (Meleagris gallopavo silvestris) were calculated using 20% kernel isopleths onto the United States Geological Survey (USGS) National Land Cover Data Base 2001 (NLCD 2001). Core use areas for all combined individuals contained evergreen forest (86%), mixed forest (9%), developed/open (roads) (7%), woody wetlands (7%), shrub/scrub (2%), and herbaceous (2%). As evergreen forest dominated core use areas during spring, road segments were selected within this cover type to be included in experimental route placement. Texas Department of Transportation (TXDOT) road shapefiles were obtained from Texas Natural Resource Information System (TNRIS) for Angelina, Houston, Jasper, Nacogdoches, Newton, Polk, Trinity, Tyler, San Augustine, and Sabine counties. A 400 m buffer was placed on all road segments within each county and then overlaid road segment buffers onto the NLCD 2001 and used the zonal statistics to identify all road buffers containing ≥ 50% evergreen forest coverage. All existing TPWD gobble count routes within the 10 county study area met new route placement criteria. Ten routes (8 experimental, 2 WMA routes) were sampled 15 March - 1 April, 2008 and 2009 where 7 of 10 routes detected vocalizing turkeys, with a maximum of 8 individuals detected on a given sampling day. Existing TPWD gobble count routes occurred within criteria developed for optimal gobble count route placement throughout east Texas, and experimental routes developed following habitat use characteristics of transmittered turkeys were successful in detecting turkeys. In sum, gobble count surveys appear to be useful for determining presence or occupancy, but are not likely to have enough detections to develop accurate population estimates. Forest cover may change rapidly in eastern Texas, depending upon timber market demands and harvest, where turkeys may move into areas where they may escape detection by gobble count surveys. This research demonstrates the utility of combining biologically relevant field data and geospatial tools for adaptive gobble count route placement. If gobble count surveys are aimed at detecting presence rather than abundance, they maintain both validity and utility, whereby adaptive route placement can be periodically adjusted in response to turkey habitat changes over time.
Management Implications:Although Texas Parks and Wildlife Department staff normally conduct gobble count surveys, the location of old routes was based upon perceived location of birds and known (generalized) release/translocation areas. As such, there has been concern that the normal surveys executed do not accurately reflect potential turkey habitats or turkey population trends. Through detailed habitat measurements, both in the field and using GIS and landcover analyses, we were able to deploy experimental routes. This approach will be useful in relocating routes in east Texas when potentially suitable habitats change or age, or when a more extensive turkey survey approach is developed for east Texas turkey monitoring. Although the experimental routes were not necessarily superior in detecting turkeys from the previously established routes, turkeys were detected on these experimental routes. Most importantly, turkeys were detected in areas of the Angelina National Forest and in the 10 county area that are not normally surveyed. As such, the approach used herein (to develop/identify new routes) has significant potential to rapidly deploy new routes as turkey populations expand, retreat, or stabilize throughout east Texas.
Citation:Conway, W. C., and J. R. Bass. 2010. Combining gobble counts, infrared camera surveys, and GIS to improve survey accuracy, estimate metapopulation size, and evaluate habitat use of eastern wild turkeys in east Texas. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Comparison of molecular markers in the endangered black-capped vireo (Vireo atricapilla) and their interpretation in conservation
Journal/Year:The Auk/2010
View:Visit The Auk, Volume 127, Issue 4, 1 October 2010, Pages 797–806
Author(s):Robert M. Zink|Andrew W. Jones|C. Craig Farquhar|Michael C. Westberg|Jose I. Gonzalez Rojas
Keywords:black-capped vireo|conservation genetics|microsatellite|mtDNA|reciprocal monophyly|Vireo atricapilla
Abstract:Previous microsatellite analysis (Barr et al. 2008) of the endangered Black-capped Vireo (Vireo atricapilla) revealed a low (FST = 0.021) but statistically significant level of population differentiation with isolation by distance (IBD); most pairwise FST values among populations were significant. No clear geographic pattern was detected, although populations in Oklahoma were somewhat differentiated, as expected from the observed pattern of IBD. Because nuclear loci, including microsatellites, coalesce more slowly that mtDNA, we sequenced the mitochondrial ND2 gene for 108 individuals sampled from breeding populations in Oklahoma, Texas, and Mexico to determine whether there was a clearer geographic pattern than that resolved by the microsatellite allele-frequency data. We obtained an FST value of 0.024 (P = 0.08), confirmed IBD, but also did not detect geographic structuring in the haplotype network. The authors of the microsatellite study suggested that the significant FST value indicated that populations were not currently connected by gene flow and that the greater attention should be given to dispersal behavior when considering the species' population dynamics. We suggest that the unstructured haplotype network reveals that the Black-capped Vireo can be managed without regard for genetic distinctiveness. That is, we contend that statistical significance of the microsatellite FST value has been inappropriately equated with biological significance. We believe that a gene-tree approach, emphasizing reciprocal monophyly, is more appropriate when assessing genetic subdivisions in a species that might then merit special conservation concern.
Management Implications:It is important that all species of conservation concern receive a "genetic checkup" to document the existence of cryptic taxa, levels of gene flow, IBD, and other factors that could play roles in developing management guidelines (in addition to demographic and ecological considerations). An mtDNA survey should be included to detect recently isolated groups, and reciprocally monophyletic groups of populations should receive high priority for preservation, regardless of their current taxonomic status (Zink 2004). We hasten to add that morphologically diagnosable groups are also important candidates, regardless of their support from molecular markers. Groups that differ only in gene frequencies ought to have lower priority. When nuclear loci are used to reduce confidence intervals on migration rates, times of divergence, and estimates of population expansion (Edwards and Beerli 2000), we are swayed by arguments that sequence data are preferable (Carstens and Knowles 2007), owing to several problematic attributes of microsatellites (Brito and Edwards 2008). Then, gene trees can be explored using coalescence analyses and compared across genes. Finally, we encourage continued dialogue over how to interpret or prioritize genetic data for conservation, given the caveat that not all populations can be saved.
Citation:Zink, R. M., A. W. Jones, C. C. Farquhar, M. C. Westberg, and J. I. Gonzalez Rojas. 2010. Comparison of molecular markers in the endangered black-capped vireo (Vireo atricapilla) and their interpretation in conservation. The Auk 127:797-806.
Title:Encounter rates from road-based surveys of Rio Grande wild turkeys in Texas
Journal/Year:Journal of Wildlife Management/2010
View:Visit BioOne - Encounter rates from road-based surveys of Rio Grande wild turkeys in Texas
Author(s):Devin R. Erxleben|Matthew J. Butler|Warren B. Ballard|Mark C. Wallace|Jason B. Hardin|Stephen J. DeMaso
Keywords:decoy|detectability|distance sampling|encounter rate|line transect|roads|simulation|survey effort|Texas|wild turkey
Abstract:Traditional index-based techniques have indicated declines in Rio Grande wild turkey (Meleagris gallopavo intermedia; hereafter, wild turkey) populations across much of Texas, USA. However, population indices can be unreliable. Research has indicated that road-based surveys may be an efficacious technique for monitoring wild turkey populations on an ecoregion level. Therefore, our goal was to evaluate applicability of road-based distance sampling in the Cross Timbers, Edwards Plateau, Rolling Plains, and South Texas ecoregions of Texas. We conducted road-based surveys in each ecoregion during December 2007-March 2008 to estimate wild turkey flock encounter rates and to determine survey effort (i.e., km of roads) required to obtain adequate sample sizes for distance sampling in each ecoregion. With simulations using inflatable turkey decoys, we also evaluated effects of distance to a flock, flock size, and vegetative cover on turkey flock detectability. Encounter rates of wild turkey flocks from road-based surveys varied from 0.1 (95% CI = 0.0-0.6) to 2.2 (95% CI = 0.8-6.0) flocks/100 km surveyed. Encounter rates from surveys restricted to riparian communities (i.e., areas ≤ 1 km from a river or stream) varied from 0.2 (95% CI = 0.1-0.6) to 2.9 (95% CI = 1.5-6.7) flocks/100 km surveyed. Flock detection probabilities from field simulations ranged from 22.5% (95% CI = 16.3-29.8%) to 25.0% (95% CI = 13.6-39.6%). Flock detection probabilities were lower than expected in all 4 ecoregions, which resulted in low encounter rates. Estimated survey effort required to obtain adequate sample sizes for distance sampling ranged from 2,765 km (95% CI = 2,597-2,956 km) in the Edwards Plateau to 37,153 km (95% CI = 12,861-107,329 km) in South Texas. When we restricted road-based surveys to riparian communities, estimated survey effort ranged from 2,222 km (95% CI = 2,092-2,370 km) in the Edwards Plateau to 22,222 km (95% CI = 19,782-25,349 km) in South Texas.
Management Implications:If surveys are restricted to riparian communities, 128 16-km transects surveyed during PM in the Edwards Plateau and 246 16-km transects surveyed during AM in the Rolling Plains would be adequate (≥ 0.80 power) to detect a 35-50% change in population density in ≤ 3 years. Though much longer periods are needed to detect smaller population changes (8-12 yr to detect a 10-25% change; Butler et al. 2007a), typically detection of a 25-50% change is desired for management purposes (Robson and Regier 1964, Healy and Powell 1999). However, feasibility of road-based surveys may vary depending on time and personnel constraints, availability of roads, and fiscal restraints. Additionally, traffic conditions may influence encounter rates but we lacked data in the current study to examine this prospect. Finally, our survey protocols may not be applicable to other parts of the wild turkey's range. Wildlife managers should develop survey protocols tailored to the conditions of the region in which they work.
Citation:Erxleben, D. R., M. J. Butler, W. B. Ballard, M. C. Wallace, J. B. Hardin, and S. J. DeMaso. 2010. Encounter rates from road-based surveys of Rio Grande wild turkeys in Texas. Journal of Wildlife Management 74:1134-1140.
Title:Hatching chronology of ducks using playas in the Southern High Plains of Texas
Journal/Year:The American Midland Naturalist/2010
View:Download Johnson_etal_2010_BroodsOnPlayas.pdf
Author(s):William P. Johnson|Laura Baar|Raymond S. Matlack|Raymond B. Barron
Abstract:Breeding pair and brood surveys suggest that duck production in the Southern High Plains can be substantial in some years, particularly for Mallards (Anas platyrynchos). Management of habitats used by nesting ducks and brood surveys could be improved with knowledge of hatching chronology. We studied hatching chronology and brood abundance of waterfowl using playa wetlands in the Southern High Plains of Texas in 2005 and 2007 (playas were dry in 2006). Broods were found on 67% (n=36) and 79% (n=19) of wet playas in 2005 and 2007, respectively. Broods per playa averaged 1.9 (± 0.4 SE) in 2005 and 3.2 (± 1.0 SE) in 2007. Hatching peaked during 1-15 Jun. and by 15 Jul. about 90% of broods had hatched. Delaying haying, mowing and other manipulations of upland nesting habitats until 15 Jul. should give 90% of broods a chance to reach playas. Brood abundance peaked during the two Jul. periods; production surveys conducted during Jul. should capture >70% of broods.
Citation:Johnson, W. P., L. Baar, R. S. Matlack, and R. B. Barron. 2010. Hatching chronology of ducks using playas in the Southern High Plains of Texas. American Midland Naturalist 163:247-253.
Title:Impact of exotic invasive plants and current land use practices on wintering avian community structure in Texas Coastal Prairie
Journal/Year:TPWD Final Report/2010
View:Download Conway_etal_2010_ExoticPlantsAvianCommunity.pdf
Author(s):Warren C. Conway|David T. Saalfeld|Christopher M. Frey|Kevin Hartke
Abstract:Grassland dependent birds have been reported to be the most imperiled assemblage of migratory birds in North America. Although many migratory grassland passerines complete their annual life cycle within the United States, investigations into wintering ecology of these species are scarce, but important, particularly in ecoregions where habitat suitability and quality is considered to be compromised, such as the Texas coastal prairie. During 2008-2010, we investigated wintering grassland bird ecology as related to coastal prairie composition and management practices on the mid-upper Texas coast. To quantify grassland bird diversity, composition, and density among management regimes, 249 transect surveys were performed on 28 different study site pastures deployed among seven different management regimes from 28 October 2008-7 April 2009 and 17 November 2009-17 March 2010. Habitat structure, native and exotic plant composition and food availability was quantified using 596 vegetation sampling points and 513 seed traps deployed throughout the study period. A total of 74 bird species (48 species in 2008-2009 and 60 species in 2009-2010) were recorded during surveys, and individual species densities estimates were calculated for eight species in 2008-2009 and for five species in 2009-2010. Bird species composition and densities varied between sampling periods (i.e., late fall-early winter or mid winter-early spring) and among management regimes, but were similar between years. Savannah Sparrow (Passerculus sandwichensis) and Eastern Meadowlark (Sturnella magna) densities and abundance were ubiquitous among study sites. However, Le Conte's Sparrow (Ammodramus leconteii) and Sedge Wren (Cistothorus platensis) reached their highest densities in habitats with greater vertical vegetation density, whereas the pipits (American Pipit [Anthus rubescens] and Sprague's Pipit [Anthus spragueii]) and Killdeer (Charadrius vociferous) reached greater densities in habitats with little or no vertical vegetation structure. Eastern Meadowlark, Sprague's Pipit, Sedge Wren, Savannah Sparrow and Le Conte's Sparrow were the most abundant birds among all study sites.
Management Implications:Within coastal Texas prairies, controlling exotic invasive plant species is a primary management goal. Previous studies in south Texas found that species richness (i.e., diversity) of birds was greater in native grasslands than in exotic grasses (Woodin et al. 2010). In this study, disturbed sites (i.e., those that contain exotic invasive plant species) had similar bird diversity as most managed prairies, however, the diversity of obligate and facultative grassland bird species was lower than in other management regimes. For example, disturbed sites were typically occupied by more cosmopolitan species (e.g., Eastern Meadowlark, and Savannah Sparrow) that have less rigorous habitat requirements, while obligate grassland bird species such as Sedge Wrens had higher densities in grasslands with fewer exotic invasive plants species. Furthermore, higher densities of birds observed in disturbed sites could be a result of poor seed crop in native prairies during 2010 that potentially forced birds to take advantage of whatever food was available (i.e., seeds from exotic species). In addition to reducing floristic diversity and impacting food availability (Flanders et al. 2006), exotic invasive plant species may alter flow of energy and nutrients in the soil (Christian and Wilson 1999), fire regimes (Brooks et al. 2004), and rates of litter accumulation and decomposition (Olge and Reiners 2003), resulting in dramatic alterations to prairie functions. Because of this, prairies may become functionally smaller, reducing functional grassland habitats available to over-wintering birds. Due to the continual decline in prairie habitat throughout coastal Texas it remains important to not only manage for vegetation structure but also control exotic invasive species.
Citation:Conway, W. C., D. T. Saalfeld, C. M. Frey, and K. Hartke. 2010. Impact of exotic invasive plants and current land use practices on wintering avian community structure in Texas Coastal Prairie. Texas Parks and Wildlife Final Report, Austin, USA.
Title:Monitoring golden-cheeked warblers on private lands in Texas
Journal/Year:Journal of Wildlife Management/2010
View:Visit JSTOR - Monitoring golden-cheeked warblers on private lands in Texas
Author(s):Bret A. Collier|Michael L. Morrison|Shannon L. Farrell|Andrew J. Campomizzi|Jerrod A. Butcher|K. Brian Hays|Darryl I. Mackenzie|R. Neal Wilkins
Keywords:breeding range|Dendroica chrysoparia|fragmentation|golden-cheeked warbler|habitat loss|patch area|patch occupancy|Recovery Credit System
Abstract:A majority of North American breeding habitat for neotropical migrants exists on private lands, requiring monitoring strategies focused on habitat in these private holdings. We outline study designs and protocols using repeated presence-absence surveys across a gradient of patch sizes to develop a range-wide monitoring program for the endangered golden-cheeked warbler (Dendroica chrysoparia) in Texas, USA. We surveyed 200-400 point-count locations across approximately 30 private properties annually from 2005 to 2008. We used data from our surveyed patches (n = 147) and the Ψ (occupancy), p (detection), and γ = 1 - ε parameterization to estimate patch dynamics and associated detection probabilities for golden-cheeked warblers. Patch size had a strong association with patch occupancy, and all patches >160 ha were predicted to be occupied. We found no evidence that large golden-cheeked warbler populations located on public lands in the vicinity of our study area influenced occupancy dynamics. We conducted simulations across a range of detection probabilities to evaluate potential sample sizes for both standard- and removal-based occupancy modeling. Simulations using parameter estimates from our analysis indicated that removal-based sampling is superior to standard sampling. Based on our results, surveying golden-cheeked warbler presence in oak-juniper (Quercus-Juniperus) patches under a removal modeling framework should be considered as one alternative for range-wide monitoring programs because patch-level monitoring would be necessary to estimate proportion of range occupied. Large contiguous patches are rare across the species' range; hence, conservation and management of the mosaic of smaller patches within a landscape context would be required for maintaining species viability. Thus, we recommend the identification of areas where smaller, contiguous patches represent a significant portion of the available habitat within the local landscape and targeting these areas for habitat maintenance and improvement.
Management Implications:Future golden-cheeked warbler surveys should be conducted between 15 March and 1 May each year to take advantage of high detection probabilities during this period. In the context of recovery planning, monitoring and evaluating patch-occupancy dynamics should occur among smaller patches (< 160 ha). Work within larger patches should focus on intra-patch distribution, patch level abundance and productivity. Future monitoring data following our design should be used for supporting approaches to minimize or mitigate against future habitat loss in highly vulnerable areas across the species' range. We suggest that the study design and analyses used herein for the golden-cheeked warbler would be applicable to other rare, woodland endemic species.
Citation:Collier, B. A., M. L. Morrison, S. L. Farrell, A. J. Campomizzi, J. A. Butcher, K. B. Hays, D. I. MacKenzie, and R. N. Wilkins. 2010. Monitoring golden-cheeked warblers on private lands. Journal of Wildlife Management 74:140-147.
Title:Pre-windenergy development assessment of the avian community in the central Texas panhandle
Journal/Year:Thesis/2010
View:Download Wulff_2010_PreWindEnergyAvian.pdf
Author(s):Sarah Wulff
Citation:Wulff, S. 2010. Pre-windenergy development assessment of the avian community in the central Texas panhandle. Thesis, Texas Tech University, Lubbock, USA.
Title:Prey use by Swainson's hawks in the lesser prairie-chicken range of the southern High Plains of Texas
Journal/Year:Journal of Raptor Research/2010
View:Visit BioOne - Prey use by Swainson's hawks in the lesser prairie-chicken range of the southern High Plains of Texas
Author(s):Adam C. Behney|Clint W. Boal|Heather A. Whitlaw|Duane R. Lucia
Keywords:Swainson's hawk|Buteo swainsoni|Lesser prairie-chicken|Tympanuchus pallidicinctus|diet|Great Plains|Texas
Abstract:We used video recordings to monitor five nests of Buteo swainsoni and determine its possible predator-prey relationship with a sympatric species of bird, Tympanuchus pallidicinctus, which is a candidate for federal protection in the southern high plains in Texas. No individuals of T.pallidicinctus were detected between 266 prey items that could be identified to be delivered in the nests of B.swainsoni. Mammals, reptiles, amphibians and birds accounted for 65%, 8%, 2% and 1% of prey delivered to the nest, respectively, and 80%, 4%, 0.4 and 1% of the biomass delivered, respectively. The most frequently observed mammalian prey delivered was squirrel Spermophilus spilosoma; other common prey were mammals Dipodomys ordii, Eumeces obsoletus and lizard Phrynosoma cornutum. Our results suggest that individuals of B. swainsoni nesting in this region do not currently constitute a threat to population T. pallidicinctus in southern high plains of Texas.
Management Implications:Raptors sometimes attempt to capture Lesser Prairie-Chickens (Behney 2009) and are occasionally successful (e.g., Haukos and Broda 1989). Our results suggest there is little cause for concern of Swainson's Hawks' depredation posing a population-level influence on Lesser Prairie-Chickens in our study area. Although our data are limited by a small sample of Swainson's Hawk pairs, reflecting the low density of nesting hawks in the study area, we found no evidence of predation upon Lesser Prairie-Chickens. It is possible some of the unidentified prey may have been prairie-chickens, particularly chicks, but the rapidity with which the unidentified prey were consumed suggests they were very small animals. Giovanni et al. (2007) found that rapidly consumed deliveries were invertebrates or vertebrate prey that were small enough for the hawks to consume whole. Also, regardless of prey size, raptors usually pluck feathers from avian prey prior to consumption; thus, we suspect that any birds brought to the nest, including Lesser Prairie-Chickens, would have been identifiable to at least the taxonomic grouping of unknown avian prey. Although we did not detect any evidence of predation on Lesser Prairie-Chickens by Swainson's Hawks, unsuccessful predation attempts were detected at leks in the study area (Behney 2009). It is possible that individual Swainson's Hawks that experienced success preying upon prairie-chickens and, due to that success, concentrated more attention on Lesser Prairie-Chickens may have the potential of influencing localized populations because such populations are small and fragmented (Macdonald et al. 1999). This potential may be of special concern with the Lesser Prairie-Chicken due to their conservation status.
Citation:Behney, A. C., C. W. Boal, H. A. Whitlaw, and D. R. Lucia. 2010. Prey use by Swainson's hawks in the lesser prairie-chicken range of the southern High Plains of Texas. Journal of Raptor Research 44:317-322.
Title:Snowy plover movement, fidelity, and dynamics in the southern High Plains of Texas
Journal/Year:TPWD Final Report/2010
View:Download Conway_etal_2010_SnowyPlover.pdf
Author(s):Warren C. Conway|Sarah T. Saalfeld|William P. Johnson
Citation:Conway, W. C., S. T. Saalfeld, and W. P. Johnson. 2010. Snowy plover movement, fidelity, and dynamics in the southern High Plains of Texas. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Temporal and spatial patterns of bird migration in the lower Gulf Region
Journal/Year:Dissertation/2010
View:Download Contreras_2010_MigrationDynamicsDissertation.pdf
Author(s):Suzanne Contreras
Citation:Contreras, S. 2010. Temporal and spatial patterns of bird migration in the lower Gulf region. Dissertation, Texas A&M University-Kingsville, USA.
Title:The ecological implications of marsh management to wetland birds in coastal Texas
Journal/Year:Thesis/2010
View:Download Fitzsimmons_2010_MarshBirdsThesis.pdf
Author(s):Owen N. Fitzsimmons
Abstract:Texas coastal marshes have declined in number and quality, prompting the widespread use of levees and water control structures to create or enhance coastal marsh habitat. However, due to the controversial nature of these management practices, more research is needed to assess the effectiveness of these techniques in providing quality waterbird habitat. During 2007-08 and 2008-09, I investigated the effects of marsh management on bird, plant, and aquatic invertebrate communities by comparing managed and nonmanaged coastal marshes along the central Texas coast. Managed marshes supported more bird species, greater waterbird densities, greater plant diversity, and greater aquatic invertebrate biomass than nonmanaged sites. However, nonmanaged wetlands supported greater densities and more species of secretive marsh birds. The results suggest that management of coastal marshes can improve habitat quality for a large, diverse assemblage of wetland bird species compared to nearby nonmanaged coastal marshes.
Management Implications:Research findings suggest that proper management of impounded wetlands along the central coast of Texas can provide productive, diverse, high-quality habitat for many wetland bird species. Despite disturbances from hurricane storm surge, managed wetlands supported greater bird species richness, waterbird densities, and higher diversity than adjacent, nonmanaged wetlands. Factors that probably contributed to enhanced habitat quality for wetland birds in managed areas include greater invertebrate biomass and available energy, seasonal variation in hydrology, and proximity to other marsh types. The value of nonmanaged marsh was evident, also, as nonmanaged areas supported the majority of secretive marsh bird species detected as well as greater marsh bird densities throughout the study. Dependent on specific objectives, managed, impounded wetlands on the Texas coast can provide high quality habitat during crucial non-breeding periods to a large, diverse assemblage of birds, some of which are of high priority for conservation. Marsh management techniques present managers with a valuable, effective way to alleviate negative effects of recent loss and degradation of freshwater marsh on the Texas coast. The benefits of such management are justification for the establishment and continued management of impounded, freshwater marshes on the Texas coast, in conjunction with natural areas, to not only improve small-scale habitat but improve landscape-scale diversity as well.
Citation:Fitzsimmons, O. N. 2010. The ecological implications of marsh management to wetland birds in coastal Texas. Thesis, Texas A&M University-Kingsville, USA.
Title:The over-winter ecology of lesser prairie-chickens (Tympanuchus pallidicinctus) in the northeast Texas panhandle
Journal/Year:Thesis/2010
View:Download Kukal_2010_LPCOverwinterPanhandle.pdf
Author(s):Curtis A. Kukal
Abstract:Over-winter space-use and habitat selection behavior by lesser prairie-chickens (Tympanuchus pallidicinctus; LPC) in the northeast Texas Panhandle is poorly understood. We investigated home range dynamics, movement patterns, and habitat selection for over-wintering LPCs between 1 September 2008 and 28 February 2010. We observed that ≥ 98% of LPC locations were within 5.0 km of their leks-of-capture and ≥ 98% were within 2.4 km of a known lek. We did not observe LPCs utilizing agricultural fields, possibly because most agriculture near leks was dominated by wheat (Triticum aestivum). Both genders consistently selected grassland (< 15% canopy coverage of shrubs) landcover over shrubland landcover types. Our results underscore the need to conserve grassland landcover for over-wintering LPCs. We agree with previous management recommendations that rangelands within 5.0 km should be managed for over-wintering LPCs, but we further recommend prioritizing rangeland within 2.4 km of all leks in an area. For lesser prairie-chickens (Tympanuchus pallidicinctus; LPC), the effects of landscape characteristics on over-winter survival are poorly understood. We used habitat-dependant survival modeling to investigate how landscape composition and configuration at the scale of the home range affects the over-winter survival of LPCs in the northeast Texas Panhandle. We found cause-specific mortality rates were equally attributable to mammalian (M = 0.133, SE = 0.056) and avian (M = 0.198, SE = 0.063) predators. We evaluated 22 competing survival models using the second-order Akaike's Information Criterion (AICC). That model suggested larger patches of shinnery oak had a negative effect on survival. However, limited sample size likely contributed to uncertainty in our models. Our results suggested that managing for large, contiguous patches of shinnery oak would be counter-productive for LPC over-winter survival.
Management Implications:Our results indicated that LPCs tended to remain within 5.0 km their leks-of-capture and within 2.4 km of a known lek. Previous conservation and management guidelines (Applegate and Riley 1998, Jamison et al. 2002) have suggested that management should take place within 4.8 km of LPC leks. This is desirable because processes at larger spatial scales are likely important to LPCs (Westemeier 1998, Fuhlendorf et al. 2002). However, if management resources are limited our data also indicated that native prairie within 2.4 km of all leks should receive the highest priority for LPC over-winter conservation and management activities in the northeast Texas Panhandle. Determining the area necessary to maintain LPC population will depend on several factors including the number of leks in an area and their degree of overlap. If populations regularly use agriculture fields this must also be taken into consideration. Our data suggested that the assumption that over-wintering male LPCs have an equal opportunity to select resources within 4.8 km of a lek might be untenable for some populations. Our results also suggest that the over-winter period should be treated as at least 2 seasons because we observed differences in multiple space-use variables between the fall and winter seasons. Our results underscore the need to conserve landcover with < 15% canopy coverage of shrubs and < 50% canopy coverage of decadent little bluestem for over-wintering LPC in the northeast Texas Panhandle. These results must be interpreted tentatively because of low sample sizes for females. We urge future resource selection studies for LPCs to investigate habitat selection using home ranges as the available habitat to offer comparisons to this population. Finally, if LPC populations in different parts of the species' range select habitat differentially, a more regional approach to habitat management may be necessary. Our data suggested that predation by both avian and mammalian predators should be considered in management plans for over-wintering LPCs. Our data also suggested that managing for large patches shinnery oak would be counter-productive for LPC over-winter survival in the northeast Texas Panhandle. Because of the large amount of uncertainty in our survival models, we recommend further study at the scale of the home range to offer comparisons to our results.
Citation:Kukal, C. A. 2010. The over-winter ecology of lesser prairie-chickens (Tympanuchus pallidicinctus) in the northeast Texas panhandle. Thesis, Texas Tech University, Lubbock, USA.
Title:Banding to monitor survival and harvest of white-winged doves in Texas and mourning dove banding in Texas
Journal/Year:TPWD Final Report/2011
View:Download Collier_2011_WWDO.pdf
Author(s):Bret A. Collier
Citation:Collier, B. A. 2011. Banding to monitor survival and harvest of white-winged doves in Texas and mourning dove banding in Texas. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Baseline avian and vegetation communities on post oak savannah restoration areas
Journal/Year:TPWD Final Report/2011
View:Download Comer_Lundberg_2011_AvianVegetationSavannah.pdf
Author(s):Christopher E. Comer|Erica W. Lundberg
Citation:Comer, C. E., and E. W. Lundberg. 2011. Baseline avian and vegetation communities on post oak savannah restoration areas. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Chronology of Rio Grande wild turkey flocking behavior in the Texas Rolling Plains
Journal/Year:Proceedings of the National Wild Turkey Symposium/2011
Author(s):Ryan M. Swearingin|Mark C. Wallace|Warren B. Ballard|Matthew J. Butler|Richard S. Phillips|Ryan N. Walker|Stephanie McKenzie-Damron|Donald C. Ruthven, III
Keywords:chronology|flocking behavior|Meleagris gallopavo intermedia|Rio Grande wild turkeys|roosting|Texas
Abstract:Rio Grande wild turkey (Meleagris gallopavo intermedia) winter flocks are often >200 birds on the roost. Evaluations of winter flock congregation timing and potential climatic correlates that may influence this behavior are lacking. We used opportunistic flock counts (n = 3,047) and roost counts (n = 101) to identify the timing of winter congregation, peak concentrations, and breakup of winter roosting flocks. We examined possible relationships between roost and flock counts and climatic variables. We found winter congregation occurred from 15 November to 1 March, peak concentrations occurred from 16 January to 1 March, and breakup occurred from 1 March to 15 April. Flock sizes were correlated negatively with maximum daily temperature, minimum daily temperature, and length of photoperiod. Roost counts were related to minimum daily temperature. Daily rainfall and snowfall were not correlated with either flock size or roost occupancy. Our results suggested that flocks are largest and roost occupancy is maximized during the coldest temperatures between 16 January and 1 March.
Management Implications:An understanding of grouping phenology can help managers set harvest strategies to meet management goals. Season dates can be manipulated based on grouping characteristics to create more opportunities for hunters by either beginning seasons later in the spring or earlier in the fall to ensure wild turkeys are dispersed across more properties. The opposite also may be attained if a reduction in harvest is essential. In states such as Texas, where the number of wild turkey licenses is dictated by the number of hunters purchasing them, adjusting season dates could have a sizeable impact on hunter success as opposed to regulating the number of wild turkey licenses issued by unit as in other states. Thomas et al. (1966) and Cook (1973) suggested that using landowner roost counts were adequate to index wild turkey populations if roosting patterns were stable among roost sites. Peak winter concentrations of wild turkeys at winter roosts occurred from 16 January to 1 March. Additionally, roost counts were most stable at these times as evidenced by consistently small confidence intervals. Consequently, we suggest that roost counts be performed during the coldest temperatures from mid-January through the end of February when roost occupancy is maximized.
Citation:Swearingin, R. M., M. C. Wallace, W. B. Ballard, M. J. Butler, R. S. Phillips, R. N. Walker, S. McKenzie-Damron, and D. C. Ruthven, III. 2011. Chronology of Rio Grande wild turkey flocking behavior in the Texas Rolling Plains. Proceedings of the National Wild Turkey Symposium 10:243-249.
Title:Colonial waterbird survey
Journal/Year:Bulletin of the Texas Ornithological Society/2011
View:Download Ortego_etal_2011_ColonialWaterbirdSurvey.pdf
Author(s):Brent Ortego|Marc Ealy|Greg Creacy|Larry LeBeau
Abstract:Texas Parks and Wildlife Department (TPWD) staff and volunteers conducted ground and air surveys of inland colonial waterbird nest sites at 584 locations in Texas from 1973 through 2004. There was an average of 472,466 nesting pairs sighted per year at all colonies. Cattle Egret (Bubulcus ibis), Little Blue Heron (Egretta caerulea), Snowy Egret (Egretta thula) and Great Egret (Ardea alba) were the most abundant species. The Oaks and Prairie Bird Conservation Region (BCR 21) had the most colonies with 171 and 269,210 nesting pairs. The total for the average densities for each colony from ground surveys from 1981-1990 in eastern Texas was 300,421 breeding pairs compared to 282,925 pairs observed from the air in 2002-2003. These totals were greater than the 164,720 pairs reported in coastal bays by the Texas Colonial Waterbird Society in 2003. Ground surveys in the 1980's documented some of the largest nesting populations of Little Blue Herons in the United States, but aerial surveys from 2002-04 found only 50% of the previously reported birds with few in northern counties. This population either shifted location or declined in northern counties before the aerial surveys. Great Blue Heron (Ardea herodias) and Neotropic Cormorant (Phalacrocorax brasilianus) occurred in greater numbers inland than elsewhere in Texas. The combined ground and the air surveys over 31 years provided a good characterization of the density and distribution of colonial waterbirds nesting inland in Texas. We recommend future aerial surveys be conducted at least once per decade to continue to monitor the distribution and size of colonies of each species in eastern Texas where the bulk of nesting occurs.
Management Implications:The intent for the initiation of inland surveys was to compliment annual monitoring on the Gulf Coast to monitor population trends. After 17 years and considerable effort conducting ground surveys, TPWD (Yantis 1990) tested the variability of surveyors at the same colonies and determined there was a tremendous amount of variation in population estimates between observers at inland sites. This type of variation was typical for monitoring colonial waterbirds in very dense vegetation in wetlands (Portnoy 1977, Erwin 1980, 1985, 1990, Yantis 1990). It was decided in 1992 that conducting these inland surveys on an annual basis was not warranted when considering the natural variation which occurs between wet and dry cycles along with observer bias. Even though there is a tremendous amount of variation among ground surveyors, these surveys did provide some useful information on the distribution of colonies and their relative sizes. Data for aerial flights 10 years later showed similarity in population estimates between aerial and ground surveys. Ground surveys of 1980s documented some of the largest nesting populations of Little Blue Herons in the United States (Ogden 1978). These populations either shifted their location or declined in northern counties before the flights of 2002-04. We gained a broader perspective on the magnitude of dispersed nesting on snags on major reservoirs where Great Blue Herons and Neotropic Cormorants occurred in numbers greater than elsewhere in Texas. The combined ground and air surveys over 31 years give a good characterization of the density and distribution of colonial waterbirds nesting in Texas. We recommend that aerial surveys be conducted in the future at least once per decade to continue to monitor the distribution and size of colonies of each species in eastern Texas where the bulk of nesting occurs.
Citation:Ortego, B., M. Ealy, G. Creacy, and L. LeBeau. 2011. Colonial waterbird survey. Bulletin of the Texas Ornithological Society 44:51-67.
Title:Distribution, fidelity, and abundance of Rio Grande wild turkey roosts in the Texas coastal sand plains
Journal/Year:Proceedings of the Annual Conference of the Southeast Association of Fish and Wildlife Agencies/2011
Author(s):Robert J. Caveny|Stephen J. Voelkel|William T. Brademan|Jason B. Hardin|Markus J. Peterson|Bret A. Collier
Keywords:abundance|aerial surveys|distribution|occupancy|Rio Grande wild turkey|roost surveys
Abstract:Sustainable management of wild turkeys (Meleagris gallopavo) requires information on distribution and abundance across the range. Techniques for surveying wild turkey populations in Texas are constrained by land access issues, requiring integration of landowners and managers into monitoring activities. We evaluated the use of 1) aerial surveys for estimating the distribution of Rio Grande wild turkeys (M. g. intermedia) relative to roosting habitat, and 2) multiple-observer roost counts for estimating local turkey abundance and roost-site fidelity within the Texas coastal sand plain. Double observer surveys indicated that detection probabilities varied little between observers, with detection rates typically exceeding 0.80. Estimated roost-site fidelity was 0.84 with roost-level detection ranging between 0.69 and 0.79. Based on these data, aerial distributional surveys conducted at the physiographic region scale combined with abundance monitoring using multiple-observer roost counts on a random sample of private lands within the region should provide a framework for long-term monitoring of Rio Grande wild turkeys in Texas and other semiarid regions of the United States.
Management Implications:Monitoring wildlife populations is essential to management; thus, application of techniques that are inexpensive yet provide precise and unbiased data are required by regulatory agencies and private land owners. Because the majority of Texas (>95%) is privately owned, aerial surveys provide a viable methodology for estimating the distribution of Rio Grande wild turkeys over large spatial areas. Although species distribution typically does not need to be determined annually (Thompson et al.1998), the frequency of distribution surveys required depends upon the magnitude of change that regulatory agency personnel wish to detect (Butler et al. 2006, 2007). Further research should delineate this relationship for Rio Grande wild turkeys in the Texas coaster sand plain. Regardless, distributional surveys conducted at the physiographic region scale combined with abundance monitoring using multiple-observer roost counts on a random sample of private lands within the region should provide a framework for long-term monitoring of Rio Grande wild turkeys in Texas and other semiarid regions of the United States.
Citation:Caveny, R. J., S. J. Voelkel, W. T. Brademan, J. B. Hardin, M. J. Peterson, and B. A. Collier. 2011. Distribution, fidelity, and abundance of Rio Grande wild turkey roosts in the Texas coastal sand plains. Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 65:45-50.
Title:Ecology of montezuma quail in the Davis Mountains of Texas
Journal/Year:Thesis/2011
View:Download Greene_2011_EcologyMontezumaQuail.pdf
Author(s):Curtis D. Greene
Abstract:Montezuma quail (Cyrtonyx montezumae) occur throughout the desert mountain ranges in the Trans Pecos of Texas as well as the states of New Mexico and Arizona. Limited information on life history and ecology of the species is available due to the cryptic nature of the bird. Home range, movements, and preferred habitats have been speculated upon in previous literature with the use of observational or anecdotal data. With modern trapping techniques and technologically advanced radio transmitters, Montezuma quail have been successfully monitored providing assessments of their ecology with the use of hard data. The objective of this study was to monitor Montezuma quail to determine home range size, movements, habitat preference, and assess population dynamics for the Davis Mountains population. Over the course of two years (2009 - 2010) a total of 72 birds (36M, 35F, 1 Undetermined) were captured. Thirteen individuals with >25 locations per bird were evaluated in the home range, movement, and habitat selection analyses. Home ranges (95% fixed kernels) were calculated resulting in a mean home range size of 2,149.4 ha with ranges varying greatly (16.8 - 15,751.4 ha). Maximum straight-line distances between known locations within home ranges varied from 0.6 - 12.7 km. Home range size and distances of movements were greater than expected. Preferred habitats consisted of Canyon Mountain Savannah and Foothill Slope Mountain Savannah across 3 spatial scales. Montezuma quail (n=72) were found to have an even 50:50 sex ratio and an annual survival estimate of 12.8%. Further documentation is needed, but much of the general ecology has been addressed by my study for Montezuma quail in the Davis Mountains of Texas.
Management Implications:Montezuma quail have been a great challenge to researchers in the past limiting what is known about movements amongst a population. Using trained dogs during the day and at night proved to be successful in capturing birds. Modern backpack style transmitters allow for prolonged monitoring and limited the radio-handicapping experienced in the past (Hernandez et al. 2004). Although my sample size is just 13, knowing Montezuma quail have the ability to make long movements and have larger than expected home ranges impact the management strategies and overall understanding of the species. Managing lands on larger scales could be valuable in expanding Montezuma quail populations. Also, knowing the ability for the ground dwelling bird to make long movements gives potential for increasing the areas occupied by Montezuma quail potentially leading back to the historical distribution that has been affected by overgrazing. Previous studies have provided information on desired habitat components and grazing strategies to benefit Montezuma quail (Brown 1982, Bristow and Ockenfels 2004, Leopold and McCabe 1957). The ability to monitor individuals with radio telemetry allowed for determining what habitat types were selected for throughout various times of the day. Land managers can focus efforts for improving habitat conditions on preferred habitat types to make management practices more effective and cost efficient. Identifying preferred areas could lead to providing insight on key areas of interest for locating Montezuma quail for hunting purposes or ecotourism.
Citation:Greene, C. D. 2011. Ecology of Montezuma quail in the Davis Mountains of Texas. Thesis, Sul Ross State University, Alpine, TX, USA.
Title:Effectiveness of surrogators as a propagation tool for northern bobwhites in south-central Texas
Journal/Year:Thesis/2011
View:Download Kinsey_2011_SurrogatorsBobwhites.pdf
Author(s):John C. Kinsey
Abstract:Attempts to restore populations of northern bobwhites (Colinus virginianus) using game-farm quail have been documented since the early 1900s. Low restoration success rates are likely the result of low post-release survival rates (8-15 days) and long distance dispersal from release sites averaging 2.33 km. Claims have been made that Surrogators®, a quail propagation tool, has increased success rates in both these areas. Following steps outlined in the Wildlife Management Technologies 2009 Surrogator System Guide, I tested the effectiveness of surrogators on bobwhite survival, dispersal, and habitat selection. I accomplished this by raising 1,000 bobwhites in two surrogators and conducting two trials per year in 2009 and 2010 on a 990-ha ranch in Wilson County, TX. Twenty bobwhites from each surrogator were fitted with transmitters 12 h before release. I attempted to locate each bobwhite daily for 3 weeks, followed by a reduced effort of three times per week until mortality reached 100%. Transmitter attachment techniques used during 2009 failed; thus no data were recorded on mortality and dispersal. Bart and Robson's Maximum Likelihood Estimators of daily survival rates calculated for bobwhites released from surrogators A and B during the first trial 2010 were low (0.87 and 0.96, respectively). Daily survival rates of bobwhites calculated for surrogators A and B in the second trial of 2010 were also low (0.83 and 0.87, respectively). Mean distances traveled by bobwhites post-release during the first trial of 2010 were 401 m and 1,416 m for surrogators A and B, respectively. Dispersal statistics were not calculated for the second trial of 2010 because of small sample size (n < 2). There was no difference in habitat use. My results do not support the use of surrogators as an effective means of restoring wild populations of northern bobwhites in southern Texas.
Management Implications:I rejected my hypothesis that the surrogator is an effective method for supplementing populations of wild bobwhites in south-central Texas. The objective of my study was to test surrogators following guidelines of the manufacturer as a means for producing viable populations of bobwhites. I did not necessarily seek to prove or disprove claims of the manufacturer. Since the surrogator has become a tool used by landowners with varying degrees of success, I sought to provide information for landowners and Texas Parks and Wildlife biologists, so an informed decision can be made by landowners in the purchase and potential use of this propagation tool. Since the early 1900s, a solution has been sought for the periodic decline in bobwhite populations. Many want a "quick fix" for the problem without understanding the ecology of bobwhites. Bobwhite populations exhibit complex dynamics in which biotic components (i.e., demographic and habitat parameters) are intricately interrelated with abiotic components (i.e., precipitation, soil, temperature, topography; Roseberry and Klimstra 1984; DeMaso et al. 2011). This irruptive population behavior in bobwhites has long intrigued and perplexed wildlife biologists and hunters. Bobwhite populations fluctuate so radically in semi-arid environments that these population changes are referred to as boom and bust cycles (Bridges et al. 2001; Hernández et al 2007). Survival rates recorded in this study do not support the 65%-90% survival to bobwhite hunting season claimed by WMT. Likewise, claims that chicks raised in surrogators imprint to local areas were not supported by my results. The results of the distribution analysis raise questions as to how large a property has to be before bobwhites will truly be imprinted. The claim made by WMT that bobwhites released from surrogators will behave like wild bobwhites was also not supported by my results. Wild populations of bobwhites have specific habitat requirements that were not selected for by bobwhites in my study. The results of my study indicate surrogators are not an effective propagation tool for the restocking of bobwhite populations in south-central Texas. A best practice for maintaining consistent bobwhite populations is to invest in habitat management by increasing native bunch grasses, controlling overgrazing by livestock, use of prescribed burning, and control for overharvest of the annual production of bobwhites.
Citation:Kinsey, J. C. 2011. Effectiveness of surrogators as a propagation tool for northern bobwhites in south-central Texas. Thesis, Texas State University-San Marcos, USA.
Title:Guide to abundance estimation techniques for Rio Grande wild turkey
Journal/Year:TPWD Final Report/2011
View:Download Locke_etal_2011_GuideRGWT.pdf
Author(s):Shawn L. Locke|James C. Cathey|Bret A. Collier|Jason B. Hardin
Abstract:Interest in habitat and population management for wild turkeys (Meleagris gallopavo) has grown in recent times, as landowners, hunters, and wildlife viewers recognize their actions have direct impacts on natural resources and wildlife populations.
Management Implications:Estimating abundance of wildlife including RGWTs is difficult and each method is not without inherent biases. However, the 3 methods presented here offer landowners and managers the opportunity to generate reasonable estimates of RGWTs on their property for better management of the species. In our experience, we feel traditional roost counts are the most efficient and cost effective method for estimating the number of RGWTs. Roost counts conducted annually provide a good indication of population trends and flock composition.
Citation:Locke, S. L., J. C. Cathey, B. A. Collier, and J. B. Hardin. 2011. Guide to abundance estimation techniques for Rio Grande wild turkey. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Impacts of introduced grasses on breeding season habitat use by northern bobwhite in the south Texas plains
Journal/Year:Journal of Wildlife Management/2011
View:Visit Wiley Online Library - Impacts of introduced grasses on breeding season habitat use by northern bobwhite in the south Texas plains
Author(s):Joseph P. Sands|Leonard A. Brennan|Fidel Hernandez|William P. Kuvlesky, Jr.|James F. Gallagher|Donald C. Ruthven, III|James E. Pittman, III
Keywords:buffelgrass|Colinus virginianus|Eragrostis lehmanniana|introduced grasses|lehmann lovegrass|northern bobwhite|Pennisetum ciliare|saddlepoint approximation|South Texas plains
Abstract:Introduced grasses may affect diversity of native fauna and flora adversely, and disrupt ecosystem processes. Many rangelands in South Texas have been seeded to or have been colonized by buffelgrass (Pennisetum ciliare) and Lehmann lovegrass (Eragrostis lehmanniana), perennial bunchgrasses native to Africa. The objective of this research was to quantify impacts that these 2 species of introduced grasses may have on northern bobwhite (Colinus virginianus) habitat use on South Texas rangelands during the breeding period (Apr-Aug).We evaluated the effects of buffelgrass and Lehmann lovegrass on northern bobwhite nest habitat (n = 35 nests) and general habitat use sites (n = 86 radiomarked quail) with logistic regression and habitat selection functions based on simple saddlepoint approximations. Buffelgrass was used as a nesting substrate at 11% of nests; however, vegetation height and visual obstruction between 1 cm and 30 cm were the best predictors of nest site use. Areas of introduced grass coverage ≥ 15-20% were avoided by northern bobwhites at general habitat use organism-centered points, but not at nest site use points. Introduced grass coverage and forb coverage were the best predictors of general habitat use, and bobwhites avoided areas with ≥ 18% introduced grass cover. These results suggest that avoidance of areas with extensive introduced grass cover may indicate a reduction in usable habitat space for northern bobwhite in the western South Texas plains. Maintaining native grass stands while implementing localized control of introduced grasses could be used as a strategy to promote habitat for northern bobwhites.
Management Implications:Microhabitats composed of introduced grasses can provide usable space for some aspects of northern bobwhite life history (e.g., nesting), but not others (e.g., general habitat use). With respect to general habitat use, relatively small amounts of introduced grasses (e.g., < 10%) may not pose an immediate threat to northern bobwhite habitats, but promoting native grass stands on a landscape scale, and implementing localized control methods for introduced grasses, could help maximize usable space for northern bobwhites. Complete elimination of introduced grasses on a landscape scale is improbable, but managers and landowners interested in providing northern bobwhite habitat should determine the abundance of introduced grass on their lands, and work to control the spread of these grasses.
Citation:Sands, J. P., L. A. Brennan, F. Hernandez, W. P. Kuvlesky, Jr., J. F. Gallagher, and D. C. Ruthven, III. 2011. Impacts of introduced grasses on breeding season habitat use by northern bobwhite in the south Texas plains. Journal of Wildlife Management 76:608-618.
Title:Impacts of wildfire on avian communities of south Texas
Journal/Year:Thesis/2011
View:Download deVerteuil_2011_WildfireAvianThesis.pdf
Author(s):Michele Lisa de Verteuil
Abstract:On March 14, 2008, an intense wildfire occurred on the Chaparral Wildlife Management Area, located in southern Texas. I sought to examine effects of the fire on avian species abundance and composition by comparing avian species richness, density and presence, and vegetation components on burned and unburned sites. I conducted transect and point-count surveys in winter and summer 2009-2010. Burned sites had higher species richness both winter seasons, but no treatment effect was observed for summer. I observed higher densities and probabilities of presence on burned sites for several granivorous, insectivorous, and/or ground-nesting birds, including several migratory grassland sparrows, during both winter seasons,. Probabilities of presence increased for most winter birds over time, whereas decreases were observed during summer. Most vegetation components showed substantial recovery 2 years post-fire. The effects of wildfire were generally positive for the avian community, and increased habitat for grassland-obligate birds without substantial impact on resident shrubland species.
Management Implications:Habitat loss through land use changes has often been implicated as a primary reason for the decline in grassland bird abundance (Knopf 1994). Habitat degradation of south Texas shrub-grasslands through fire suppression and brush encroachment is also a substantial threat to both grassland bird breeding and wintering habitat (Lloyd et al. 1998, Grant et al. 2004). Although the wildfire on the Chaparral WMA was large and intense, it burned patchy in areas, and this mosaic pattern increased structural heterogeneity of woody plants and made habitat more suitable for wintering grassland birds without serious impact on resident shrubland species. Despite the intensity of the wildfire, percent cover of most groundcover components was similar on burned and unburned sites within 2 years post-fire, which is similar to recovery times for prescribed fire in this region. Private and public land managers wanting to increase or sustain avian species richness for the purposes of ecotourism or gamebird production should utilize prescribed fire, when possible, and maintain their land in a variety of post-fire successional stages to maintain habitat heterogeneity for a diversity of game and nongame avian species. Although the wildfire at the Chaparral WMA was large and intense, it was a patchy fire and produced a mosaic of groundcover in varying seral stages, as well as increased heterogeneity in woody vegetation height. Despite the fire's scale, intensity, and occurrence during extreme fire conditions (low humidity, high winds, etc.), recovery time for most vegetation components were similar to observed recovery times for prescribed fire in this region (Reynolds and Krausman 1998, Ruthven and Synatzke 2002, Mix 2004).Effects from the fire on birds were generally positive, and foraging quality on the burned sites increased for a number of grassland granivorous and insectivorous species. Shrub-obligates were relatively unaffected, with the exception of Verdin and Bell's Vireo. Drought was a confounding factor in this study, and led to reductions in likelihood of occurrence for a number of species, regardless of study area. Land managers looking to maintain or enhance avian species diversity should utilize prescribed fire to provide a mosaic of post-fire seral stages. Efforts should also be made to utilize prescribed fire opportunities in the early growing season (Ansley and Jacoby 1998) in order to more effectively control woody plant encroachment and density.
Citation:de Verteuil, M. L. 2011. Impacts of wildfire on avian communities of south Texas. Thesis, Texas A&M University-Kingsville, USA.
Title:Improving lesser prairie-chicken lek surveys on private lands
Journal/Year:TPWD Final Report/2011
View:Download Ballard_etal_2011_LPCPrivateLands.pdf
Author(s):Warren B. Ballard|Matthew J. Butler|R. Douglas Holt
Citation:Ballard, W. B., M. J. Butler, and R. D. Holt. 2011. Improving lesser prairie-chicken lek surveys on private lands. Texas Parks and Wildlife Final Report, Austin, USA.
Title:Interactions of raptors and lesser prairie-chickens at leks in the Texas southern High Plains
Journal/Year:The Wilson Journal of Ornithology/2011
View:Download Behney_etal_2011_RaptorsLPCLeks.pdf
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Author(s):Adam C. Behney|Clint W. Boal|Heather A. Whitlaw|Duane R. Lucia
Abstract:We examined behavioral interactions of raptors, Chihuahuan Ravens (Corvus cryptoleucus), and Lesser Prairie-chickens (Tympanuchus pallidicinctus) at leks in the Texas Southern High Plains. Northern Harriers (Circus cyaneus) and Swainson’s Hawks (Buteo swainsoni) were the most common raptors observed at leks. Only 15 of 61 (25%) raptor encounters at leks (0.09/hr) resulted in a capture attempt (0.02/hr). Mean (±SD) time for Lesser Prairie-Chickens to return to lekking behavior following a raptor encounter was 4.2 ± 5.5 min suggesting the disturbance had little influence on lekking behaviors. Lesser Prairie-Chickens engaged in different escape behaviors depending on raptor species and, generally, did not respond to ravens suggesting they are able to assess different predation risks. The raptors in our study area posed little predation risk to lekking prairie-chickens. Behavioral disturbance at leks appears minimal due to the lack of successful predation events, low raptor encounter rates, and short time to return to lekking behavior.
Management Implications:Lesser Prairie-Chicken responses to predation attempts appear to correspond to the hunting strategies of different raptor species. Northern Harriers and buteo hawks (including Swainson's Hawks) typically capture prey on the ground and would likely have difficulty overtaking and catching a prairie-chicken in the air (Macwhirter and Bildstein 1996, England et al. 1997). These raptor species elicited more flushing responses from prairie-chickens. Falcons evolved to overtake and capture prey in the air (Webster 1944, White 1962), and elicited more of a squatting response and an observable hesitancy to flush by prairie-chickens. This suggests Lesser Prairie-Chickens are able to assess the threat posed by different raptors species and have evolved the appropriate behavioral response. We are confident we detected all raptor predation attempts on Lesser Prairie-Chickens at leks during monitoring and video-recording periods. However, it is possible that we missed some raptor fly-bys or coursing that occurred behind or over the blind or camera. We believe any observer effect on raptor presence or behavior was minimal due to the small size of the blind, our arrival well before sunrise, and that we remained stationary throughout the observation period. Encounter rates were higher for direct observation than video-recording, suggesting observer presence was not inhibiting raptor presence. Raptors were not a source of mortality or marked disturbance of Lesser Prairie-Chickens while on leks in our study. This suggests mortality of lekking Lesser Prairie-Chickens from raptor predation is not a factor contributing to population declines.
Citation:Behney, A. C., C. W. Boal, H. A. Whitlaw, and D. R. Lucia. 2011. Interactions of raptors and lesser prairie-chickens at leks in the Texas southern High Plains. The Wilson Journal of Ornithology 123:332-338.
Title:Lack of cottonwood regeneration in the southern Great Plains: implications for wild turkeys
Journal/Year:Proceedings of the National Wild Turkey Symposium/2011
Author(s):Ryan N. Walker|Mark C. Wallace|Warren B. Ballard|Richard S. Phillips|Stephanie McKenzie-Damron|Ryan M. Swearingin|Michael Janis
Keywords:cottonwood|Kansas|Meleagris gallopavo intermedia|Populus deltoides|regeneration|Rio Grande wild turkeys|Texas
Abstract:The presence of trees is an important limiting factor for wild turkeys (Meleagris gallopavo) throughout arid and semiarid portions of their range. Long-term changes in local tree populations likely will impact local wild turkey populations. Cottonwoods (Populus spp.) are the primary riparian tree of western North America and are linked to riparian systems. From 2000 through 2006, we measured 3,832 plains cottonwoods (P. deltoids monilifera) at 4 sites in the southern Great Plains of Texas and Kansas. Only 3% of these cottonwoods were < 10 cm in diameter at breast height, suggesting that cottonwoods are not regenerating. This could have negative consequences for wild turkeys in these areas.
Management Implications:Our results suggest that, within the next several decades, cottonwoods largely may disappear unless some regeneration occurs. We do not know what effect loss of cottonwoods would have on wild turkey populations, but we speculate that this would not be beneficial because nearly all of the wild turkey roosts we located were in cottonwoods. We recommend that managers continue to track cottonwood regeneration and, if necessary, begin restoration efforts such as controlled flooding and pole plantings (Friedman et al. 1998, Sprenger et al. 2002, Bhattacharjee et al. 2006, Taylor et al. 2006).
Citation:Walker, R. N., M. C. Wallace, W. B. Ballard, R. S Phillips, S. McKenzie-Damron, R. M. Swearingin, and M. Janis. 2011. Lack of cottonwood regeneration in the southern Great Plains: implications for wild turkeys. Proceedings of the National Wild Turkey Symposium 10:73-78.
Title:Nest success of snowy plovers (Charadrius nivosus) in the southern High Plains of Texas
Journal/Year:Waterbirds/2011
View:Download Saalfeld_etal_2011_NestSuccessSnowyPlover.pdf
Author(s):Sarah T. Saalfeld|Warren C. Conway|David A. Haukos|William P. Johnson
Keywords:breeding|Charadrius nivosus|nesting|nest success|nest survival|Program MARK|saline lake|surface water
Abstract:Snowy Plovers (Charadrius nivosus) nesting on edges of saline lakes within the Southern High Plains (SHP) of Texas are threatened by habitat degradation due to reduced artesian spring flow, making many saline lakes unsuitable for nesting and migrating shorebirds. Factors influencing nest success were evaluated, current nest success estimates in the SHP of Texas were compared to estimates obtained ten years prior, and causes and timing of nest failures determined. Overall, 215 nests were monitored from three saline lakes in 2008-2009, with nest success estimates from Program MARK ranging from 7-33% (x̅ = 22%). The leading causes of nest failures were attributed to predation (40%) and weather (36%). Nest success was negatively influenced by number of plants within 707-cm2 plot, positively influenced by percent surface water availability, and at one saline lake, negatively influenced by day during the nesting season (i.e. nest success declined later in the nesting season). When compared to estimates ten years prior (1998-1999), mean nest success has declined by 31%. If nesting Snowy Plovers continue to experience increased predation rates, decreased hydrological integrity, and habitat alterations, populations will continue to decline throughout this region
Citation:Saalfeld, S. T., W. C. Conway, D. A. Haukos, and W. P. Johnson. 2011. Nest success of snowy plovers (Charadrius nivosus) in the southern High Plains of Texas. Waterbirds 34:389-399.
Title:Rio Grande wild turkey diets in the Texas panhandle
Journal/Year:Proceedings of the National Wild Turkey Symposium/2011
Author(s):Mark C. Wallace|Warren B. Ballard|Ryan Swearingin|Ryan Walker|Derrick P. Holdstock|Brian Petersen
Keywords:foods|Meleagris gallopavo intermedia|seasonal|Texas
Abstract:Rio Grande wild turkey (Meleagris gallopavo intermedia) populations have been declining in the Texas Panhandle, whereas populations of Rio Grande wild turkeys in other areas of Texas have been more stable. The objective of this study was to identify the native, exotic, and anthropogenic foods in the diets of birds in the Texas Panhandle and to compare those results to previous diet studies of birds in southern and central Texas. We harvested 70 (35 females, 35 males) wild turkeys from 3 study sites in the Texas Panhandle during 4 seasons and assessed crop and esophagus contents. Annually, hackberries (Celtis spp.), peanuts (Arachis hypogaea), and woolybucket bumelia (Sideroxylon lanuginosum) were ranked highest by volume; peanuts, denseflower bladderpod (Lesquerella densiflora), and grass vegetation volumes were highest in spring, and Chickasaw plum (Prunus angustifolia) fruit, grasshoppers (Caelifera: Orthoptera), and western soapberry (Sapindus drummondii) fruit volumes were highest in summer. During autumn, woolybucket bumelia fruit, hackberries, and corn (Zea mays) ranked high by volume, and hackberries, peanuts, and western wheatgrass (Agropyron smithii) ranked high in winter. We did not have any measure of availability for food types. Consumption of anthropogenic foods varied between 7% and 43% of volume, depending upon season. We found no differences in diets between sexes. Use of anthropogenic, mast, and miscellaneous foods differed among study sites. Despite an abundance of autumn olive (Elaeagnus angustifolia), honey mesquite (Prosopis glandulosa), and saltcedar (Tamarix chinensis) on the study sites, wild turkeys did not consume any part of these plants. Managers should consider protecting hackberry, Chickasaw plum, and western soapberry as useful foods for wild turkeys.
Management Implications:Our findings indicated that, in some areas, Rio Grande wild turkey diets contain as much as 43% of foods from anthropogenic sources, depending on the season. Future research should focus on determining the effect of foods from anthropogenic sources on population dynamics, movements within suitable habitat, and population distribution across the landscape. This knowledge would allow managers to better understand how human activities are affecting wild turkey populations and would demonstrate how the use or restriction of supplemental feeding could help achieve management goals. Despite the abundance of autumn olive, a nonnative plant thought to be a valuable wildlife food, it was not consumed at any of our study sites. In addition, neither saltcedar nor honey mesquite was consumed, despite each being common on at least 2 of our study sites. These 3 species are controlled widely throughout the Texas Panhandle and continuing to do so should have no negative effect on Rio Grande wild turkey in this region. However, hackberry, Chickasaw plum, and western soapberry, which were important foods, are not always protected when managers try to eradicate undesirable brush and forb species. When possible, managers should take special precautions to protect these species because they may be important foods for wild turkeys.
Citation:Wallace, M. C., W. B. Ballard, R. Swearingin, R. Walker, D. P. Holdstock, and B. Petersen. 2011. Rio Grande wild turkey diets in the Texas panhandle. Proceedings of the National Wild Turkey Symposium 10:201-211.
Title:Rio Grande wild turkey habitat associations during dispersal
Journal/Year:Proceedings of the National Wild Turkey Symposium/2011
Author(s):Richard S. Phillips|Warren B. Ballard|Mark C. Wallace|John H. Brunjes, IV|Ernest B. Fish|Nancy E. McIntyre|Stephen J. DeMaso
Keywords:corridor|dispersal|habitat|Meleagris gallopavo intermedia|movement|riparian|wild turkey
Abstract:Wild turkey (Meleagris gallopavo) populations in the western United States often exhibit a period of movement from winter roosting flocks to summer ranges. This period may play an important role in population expansion events and in distribution of birds during harvest, yet it remains poorly understood. Using 3,767 locations from 392 yearling Rio Grande wild turkeys (M. g. intermedia) at 3 sites, we investigated habitat associations by using coverages representing habitat type, structure, and riparian classifications. Using location error polygons as subsamples, we used individual birds as our estimate of use, and we used randomly generated polygons to estimate available habitat. In addition, we compared movement-period habitat use between those birds that returned to their original winter range (resident) and those that did not (disperser). We detected no differences in habitat use between residents and dispersers at any sites during the movement period (21 Mar-1 May). During the movement period, all birds strongly selected for trees, with no across-site pattern of selection for any other habitat type. Selection for grassland components was not consistent across sites. Birds of both sexes and movement classifications selected against < 2-m height classes, but selected for > 4-m height classes. Based upon our results, it may be appropriate to infer movement habitat characteristics by using all yearling wild turkeys, regardless of the permanence of the movement, during the movement period. Although our findings concur with other studies of wild turkeys in grassland regions, the potential to assess wild turkey movement based on structure, in lieu of other classification, could prove important. Although we recommend manipulative tests, it seems that riparian areas are important to movement and connectivity among winter populations.
Management Implications:We recommend increased studies of habitat associations during the dispersal period for resident versus dispersing individuals in other areas occupied by wild turkeys that exhibit seasonal range shifts of smaller magnitudes. Our findings suggest that movement characteristics may be inferred using birds that make permanent movements and those that do not, mitigating possible sample size issues. It is clear that riparian areas are of major importance during the spring movement period in Rio Grande wild turkeys and that they should be managed with this importance in mind. However, manipulative experiments may be necessary to determine which component of the riparian area is important to facilitate movement of wild turkeys through it.
Citation:Phillips, R. S., W. B. Ballard, M. C. Wallace, J. H. Brunjes, IV, E. B. Fish, N. E. McIntyre, and S. J. DeMaso. 2011. Rio Grande wild turkey habitat associations during dispersal. Proceedings of the National Wild Turkey Symposium 10:213-225.
Title:Survival, behavior, and physical effects of surgically implanted radio transmitters on Rio Grande wild turkey poults
Journal/Year:Proceedings of the National Wild Turkey Symposium/2011
Author(s):Stephanie McKenzie-Damron|Mark C. Wallace|Warren B. Ballard|Matthew J. Butler|Donald C. Ruthven, III|Ole Alcumbrac|Ryan M. Swearingin|Ryan N. Walker
Keywords:behavior|implant|Meleagris gallopavo intermedia|methods|radio telemetry|survival
Abstract:Estimates of survival and cause-specific mortality of wild turkey (Meleagris gallopavo) poults from hatching through recruitment are critical to population modeling and management. Our objectives were to assess the effects of implanting radio transmitters on survival and behavior of Rio Grande wild turkey (M. gallopavo intermedia) poults. We also investigated the performance of radio transmitters implanted in poults. Our study was conducted on 91 captive poults. We implanted a 2.2-g radio transmitter with an internal antenna using an intra-abdominal surgical procedure. Poults were assigned randomly to 1 of 3 treatment groups including control (no surgery), surgery without implants, and surgery with implants. We found no difference in survival among treatment groups. However, immediate impairment of motor response for implanted poults was observed for up to 3 days following surgery. Behavioral differences among treatment groups were inconsistent, with no detectable pattern over 10 weeks observed post-treatment. Implanted poults gained less weight than surgery-only poults, but did not differ from the control group. No individuals lost implanted transmitters. Signals from implanted radio transmitters could be detected at a range of 30 ± 10 m for a 102-day period. Future research needs to be conducted on wild turkey poults in a field setting to assess the practicality of this technique for field use.
Management Implications:The inability to assess survival and cause-specific mortality of wild turkey poults from hatching through recruitment has hampered population modeling and management. Our procedure offers greater retention times than the glued backpacks and subcutaneous implants previously used on wild turkey poults. The procedure easily is learned and can be transferred to the field. There are initial post-surgical effects ≤ 3 days, which may require censoring or a different handling strategy with surgically implanted poults. Estimation of poult survival from hatching through the first week of life, a critical life stage, also may be precluded if there are extended recovery times from surgery. Furthermore, the need to hold some poults up to 3 days for recovery may preclude returning them successfully to their brood. However, this technique could be used to obtain survival data on free-ranging wild turkey poults for >8 months from hatching to spring recruitment. We know this technique works on healthy captive wild turkey poults, but future researchers may want to focus on criteria for identifying good candidates for implant surgery and on using this implant technique on wild turkey poults in the field.
Citation:McKenzie-Damron, S., M. C. Wallace, W. B. Ballard, M. J. Butler, D. C. Ruthven, III, O. Alcumbrac, R. M. Swearingin, and R. N. Walker. 2011. Survival, behavior, and physical effects of surgically implanted radio transmitters on Rio Grande wild turkey poults. Proceedings of the National Wild Turkey Symposium 10:111-118.
Title:The non-breeding season ecology of lesser prairie-chickens (Tympanuchus pallidicinctus) in the southern High Plains of Texas
Journal/Year:Thesis/2011
View:Download Pirius_2011_NonBreedingEcologyLPC.pdf
Author(s):Nicholas E. Pirius
Abstract:Few studies have examined the non-breeding season ecology of the lesser prairie-chicken (Tympanuchus pallidicinctus; hereafter LEPC). The majority of research efforts have focused on breeding ecology. Given dramatic declines in LEPC populations (≥ 95% loss since the 1800's), a better understanding of the species' non-breeding ecology is important for conservation efforts. I used radio telemetry to examine gender-specific habitat use, home ranges, movements/movement patterns, and survival rates during the non-breeding seasons (1 September through 28 February) of 2008-2009, 2009-2010, and 2010-2011 in the Southern High Plains of Texas. Across the three non-breeding seasons, average home range did not differ between adult females (501 ha) and adult males (480 ha). LEPCs did not use each habitat proportional to availability within the study area (x2=1868.7, α = 0.05). Grassland dominated areas with sand-shinnery oak (Quercus havardii) were used more than available. Sand-sage (Artemisia filifolia) dominated areas with bare ground, and sand-sage dominated areas with grassland were avoided. Four habitat types, mesquite (Prosopis glandulosa) savannah, reverted agriculture, sand-shinnery oak, and sand-shinnery oak dominated areas with grassland were used proportional to availability. I detected 13 mortalities (24.5%) among 53 radio tagged LEPCs. Mortalities were predominately males (77%) with the majority (6 adult male, 1 juvenile male, and 3 adult females) due to avian predation, whereas two mortalities were due to mammalian predation and one attributed to an unknown cause. Estimates of non-breeding season survival (180 days) were 84.6%, 82.7% and 57.2% for the 2008, 2009, and 2010 non-breeding seasons, respectively.
Citation:Pirius, N. E. 2011. The non-breeding season ecology of lesser prairie-chickens (Tympanuchus pallidicinctus) in the southern High Plains of Texas. Thesis, Texas Tech University, Lubbock, USA.
Title:Wild turkey (Meleagris gallopavo) association to roads: implications for distance sampling
Journal/Year:European Journal of Wildlife Research/2011
View:Visit Springer Link - Wild turkey (Meleagris gallopavo) association to roads: implications for distance sampling
Author(s):Devin R. Erxleben|Matthew J. Butler|Warren B. Ballard|Mark C. Wallace|Markus J. Peterson|Nova J. Silvy|William P. Kuvlesky, Jr.|David G. Hewitt|Stephen J. DeMaso|Jason B. Hardin|Megan K. Dominguez-Brazil
Keywords:bias|distance sampling|distribution|ecoregion|line transects|Meleagris gallopavo intermedia|Rio Grande wild turkey|roads|Texas
Abstract:Road-based distance sampling is a common technique used to estimate the density of many wildlife species but potential biases exist unless the target population is randomly distributed around roads. Our objective was to determine if and when Rio Grande wild turkeys (Meleagris gallopavo intermedia; RGWT) were randomly distributed around roads to identify time periods in which road-based surveys would be most appropriate. We used triangulated locations obtained from radio telemetry of RGWTs in the Edwards Plateau (2001-2003), Rolling Plains (2000-2006), and South Texas (2003-2006) ecoregions. Using a geographic information system, we conducted a use and availability analysis by sex, season, and time of day for each ecoregion to determine RGWT use of areas near roads (< 200 m). We found the most appropriate time to conduct road-based distance sampling was from 1 December to 15 March during morning or afternoon. Our results suggested road-based surveys conducted during these periods should yield generally unbiased results in the Rolling Plains and Edwards Plateau ecoregions. We recommend researchers and managers investigate animal distributions around roads before implementing road-based monitoring programs for other wildlife species.
Management Implications:The results from our analyses should act as a guide for determining when to conduct road-based surveys for wild turkeys. However, other factors such as flocking behavior and vegetative cover should also be considered. For example, vegetative cover may affect flock detectability, so knowledge of annual leaf fall dates would be helpful in designing survey protocols. Further, we recommend researchers and managers investigate animal distributions around roads before implementing road-based monitoring programs for other wildlife species. An important question concerning RGWT distributions around roads remains. Within the 200 m area around roads, RGWTs could exhibit small scale avoidance-attraction behaviors (see Marques 2007). However, the inherent error in radio telemetry data precludes us from examining this prospect. To reduce the inherent error associated with wildlife location data, future research examining animal distributions around roads may require the use of micro-global positioning system technology (location error < 20 m; Wegge et al. 2007). Without knowledge of animal distributions around roads, potential bias in density estimates obtained from road-based surveys cannot be known.
Citation:Erxleben, D. R., M. J. Butler, W. B. Ballard, M. C. Wallace, M. J. Peterson, N. J. Silvy, W. P. Kuvlesky, Jr., D. G. Hewitt, S. J. DeMaso, J. B. Hardin, and M. K. Dominguez-Brazil. 2010. Wild turkey (Meleagris gallopavo) association to roads: implications for distance sampling. European Journal of Wildlife Research 57:57-65.
Title:Winter roost characteristics of Rio Grande wild turkeys in the Rolling Plains of Texas
Journal/Year:Proceedings of the National Wild Turkey Symposium/2011
Author(s):Ryan M. Swearingin|Matthew J. Butler|Warren B. Ballard|Mark C. Wallace|Richard S. Phillips|Ryan N. Walker|Stephanie McKenzie-Damron|Donald C. Ruthven, III
Keywords:cottonwoods|habitat|Meleagris gallopavo intermedia|Populus deltoides|Rio Grande wild turkeys|Texas|vegetative characteristics|winter roosts
Abstract:The favored roost tree species for Rio Grande wild turkeys (Meleagris gallopavo intermedia) in the Texas Rolling Plains is the eastern cottonwood (Populus deltoids). In this region, as well as in much of the semiarid Southwest, cottonwoods are declining due to natural and human-altered river flows, invasion of exotic species such as Russian olive (Elaeagnus angustifolia) and saltcedar (Tamarix chinensis), and overgrazing. Consequently, a better understanding of the vegetation characteristics of wild turkey winter roost sites was needed. We measured roosting habitat at 32 roost sites and 32 randomly selected non-roost sites. We collected data during September-March from 2004 to 2006 at 3 study sites in the Texas Rolling Plains. We measured tree height, tree diameter, percentage of canopy cover, tree decay, area of the stand in which the roost occurred (stand area), percentage of litter cover, and percentage of shrub cover. We linked winter roost use (presence-absence) with habitat variables representing forest and vegetation structure at roost sites by creating explicit habitat models. We assess 44 a priori logistic regression models using Akaike's Information Criterion (AICC) to model roosts based on tree, understory, and stand scales. At all 3 levels we found competing models. Parameters with higher relative values included tree height, tree diameter, stand area, and percentage of litter, respectively. Based on these findings, an appropriate management strategy should include the conservation of large, open-understory, riparian stands of trees. Those stands should contain the tallest, largest-diameter trees available. We also suggest that young stands of preferred roost tree species be protected to provide future roost sites when current roosts eventually become unsuitable for wild turkeys.
Management Implications:Because appropriate size classes of key roost vegetative components vary across the wild turkey's range, we suggest optimizing habitat relative to the region based on prevailing habitat types. We suggest conservation-based, rather than manipulative, management recommendations. The largest stands with the tallest, largest-diameter trees available should be conserved. Those sites with the lowest amount of visual obstruction in the understory also should be given priority. Understory visual obstruction is the most easily manipulated variable that we examined. We suggest, if brush control is to be implemented at roost sites, that it be conducted during the spring or summer months after most winter residents have dispersed for the breeding season. This will minimize disturbance to winter concentrations. Protection of areas where cottonwood recruitment has occurred or is most likely should help to ensure that optimal roost sites will be available in the future. The eastern cottonwood is an r-selected species that relies on flood events to prepare seedbeds for seed germination (Amlin and Rood 2002). As a result, flood-prone areas that display bare soils should be monitored for cottonwood recruitment. When young seedlings are found, the area should be excluded from grazing pressure so that young seedlings are protected from herbivory. Riparian brush control also may increase the likelihood of cottonwood regeneration and provide roost trees for the future.
Citation:Swearingin, R. M., M. J. Butler, W. B. Ballard, M. C. Wallace, R. S. Phillips, R. N. Walker, S. McKenzie-Damron, and D. C. Ruthven, III. 2011. Winter roost characteristics of Rio Grande wild turkeys in the Rolling Plains of Texas. Proceedings of the National Wild Turkey Symposium 10:251-262.
Title:Wintering grassland bird density in Chihuahuan Desert grassland priority conservation areas, 2007-2011
Journal/Year:Rocky Mountain Bird Observatory Technical Report, TPWD Final Report/2011
View:Download MaciasDuarte_etal_2011_RMBOChihuahuanDesert.pdf
Author(s):Alberto Macias-Duarte|Arvind Panjabi|D. Pool|Erin Youngberg|Greg Levandoski
Abstract:Many North American grassland bird species are undergoing steep, widespread and long-term population declines, likely due to the continued habitat loss and degradation over much of their range. More than 80% of grassland bird species breeding in western North America overwinter in the Chihuahuan Desert grasslands of the southwestern United States and northern Mexico. These grasslands are increasingly being lost and degraded through agricultural conversion, desertification, and shrub encroachment, especially in Mexico. The role of threats during the wintering period in these documented population declines, although hypothesized to be important, remains unknown. In this regard, it is imperative to obtain information on wintering grassland bird distribution, abundance, habitat use and their spatiotemporal patterns to guide strategic habitat conservation in the region. In 2007, Rocky Mountain Bird Observatory (RMBO), together with Universidad Autónoma de Nuevo Leon, initiated a first-ever, region-wide pilot survey to inventory, research, and monitor wintering birds at 468 randomly-selected grassland sites in 7 Chihuahuan Desert Grassland Priority Conservation Areas (GPCAs) in northern Mexico. We have expanded this effort every year since then to eventually include 1,159 sampling locations in 16 GPCAs in northern Mexico, southeastern Arizona, southern New Mexico and west Texas in 2011. We surveyed birds at each sampling location using 1-km line transects with distance sampling to estimate bird density. We also characterized habitat structure using ocular estimates. These surveys generated data on habitat conditions and abundance of 50 grassland obligate or facultative species in the 16 GPCAs, including 29 priority species of high regional or continental conservation interest. We used Bayesian hierarchical models to obtain reasonably precise annual estimates of population density for 29 species, including 18 priority species. Wintering grassland bird communities throughout the Chihuahuan Desert are highly variable in species abundance and composition from winter to winter. Bird densities may change in orders of magnitude at the GPCA level and bird species may reach their maximum density at different GPCAs in different years. Chihuahuan Desert grassland winter avifaunal densities are characterized by the dominance of a few species including Chestnut-collared Longspur, Lark Bunting, Vesper Sparrow, Horned Lark, Brewer Sparrow, and Savannah Sparrow. In addition, a cluster analysis of GPCAs based on bird species composition shows geographically consistent groups of GPCAs suggesting a regionalization or geographic units of grassland bird species' occurrence within the Chihuahuan Desert. Analysis of biodiversity measures, mainly species richness and the Shannon-Weaver diversity index suggest that Cuchillas de la Zarca, Janos, and Malpaís harbor highly diverse grassland bird communities and should be effectively protected. Information on bird abundance and distribution generated by this project is providing valuable information to generate demographic projections and habitat models during the winter season. These tools will inform agencies and land managers on the conditions necessary to achieve target population levels of grassland bird species to ensure their long-term conservation.
Management Implications:Winter grassland bird communities throughout the Chihuahuan Desert are highly variable in abundance and composition from winter to winter. Bird densities may change in orders of magnitude at the GPCA level and bird species may reach their maxima at different GPCAs in different years. These results suggest that migratory grassland birds have low site fidelity in the wintering grounds and their movement may be largely governed by annual changes in the distribution of resources required for winter survival. Food limitation has been hypothesized to be the primary factor driving bird distribution in Chihuahuan Desert grasslands during the winter (Dunning and Brown 1982, Macias-Duarte et al. 2009), which in turn may be largely governed by summer precipitation. In this regard, this project is providing valuable information that will enable us to further explore, among other topics, the influence of climate, particularly precipitation, in the abundance and distribution of grassland birds in winter and the consequences of climate change for the persistence of grassland birds in North America. However, large annual variability in species distribution throughout the Chihuahuan Desert poses a challenge to the conservation of grassland birds since no subset of GPCAs may suffice to protect all species. In spite of the large annual variability in grassland bird abundance, some patterns are evident. Most of the species abundance (>50%) resides in less than 5 species for all GPCAs, a recurrent pattern that has been identified in other studies (Manzano-Fischer et al. 1999, Macias-Duarte et al. 2009). Dominant species at GPCAs include Chestnut-collared Longspur, Lark Bunting, Vesper Sparrow, Horned Lark, Brewer Sparrow, and Savannah Sparrow. All these species have significant declining trends in their breeding grounds according to the North American Breeding Bird Survey. Analysis of biodiversity measures, mainly species richness and Shannon's diversity index show that in order to optimize biodiversity conservation, Cuchillas de la Zarca, Janos, and Malpaís should be effectively protected. These 3 GPCAs have the highest species richness and since they belong to different clusters of GPCAs (as identified by our hierarchical cluster analysis, Fig. 2), protection of different grassland bird guilds can be achieved. Furthermore, protection of El Tokio and Valles Centrales must also be sought since these GPCAs harbor important populations of federally-recognized threatened and endangered birds and other wildlife in Mexico, including Aplomado Falcon, Mountain Plover, Mexican prairie dog, Pronghorn and others (SEMARNAT 2010). This research has also demonstrated that there is a strong relationship between vegetation structure and bird species abundance in Chihuahuan Desert grasslands (Panjabi et al. 2010a). These relationships have allowed us to develop species' habitat models to predict bird abundance in relation to changes in grassland conditions. Information generated by this project on five priority bird species' habitat needs will soon be available to land managers and ranchers interested in improving range conditions for grassland bird conservation through Rocky Mountain Bird Observatory (rmbo.org) and Rio Grande Joint Venture (rgjv.org). Incorporating new data (from 2012 and beyond) and further refining our modeling approaches will enable us to set guidelines for habitat management to achieve target population levels.
Citation:Macias-Duarte, A., A. O. Panjabi, D. Pool, E. Youngberg, and G. Levandoski. 2011. Wintering grassland bird density in Chihuahuan Desert grassland priority conservation areas, 2007-2011. Rocky Mountain Bird Observatory Technical Report I-MXPLAT-10-01, Brighton, CO, USA.
Title:A comparison of white-winged dove Zenaida asiatica densities estimated during morning and evening surveys
Journal/Year:Journal of Fish and Wildlife Management/2012
View:Download Small_etal_2012_WWDSurveysDensity.pdf
Author(s):Michael F. Small|Joseph A. Veech|John T. Baccus
Keywords:distance sampling|survey times|white-winged dove
Abstract:Surveying bird populations through visual observation is generally limited to morning. The focus on morning surveys is based on the reasonable assumption that detection is more likely when birds are most active. However, population surveys could become more time- and cost-efficient if both morning and evening sampling were equally effective, particularly for game birds, such as white-winged dove Zenaida asiatica. Texas Parks and Wildlife Department has recently implemented distance sampling to estimate population sizes and monitor an ongoing range expansion of this species. We compared morning vs. evening density estimates for white-winged doves sampled in Mason, Texas, on six separate occasions during summer 2006. Program DISTANCE (version 5.0) calculated similar detection probabilities and density estimates between paired morning and evening sampling periods. Probability of detection ranged from 0.27 to 0.46 for both morning and evening samples. Densities, in individuals/ha, ranged from 2.54 to 4.02 for morning sampling and 2.48 to 4.31 for evening sampling. In addition, variables (number of observations, cluster size, distance to cluster) used by DISTANCE did not vary substantially between morning and evening surveys. Our results suggest evening surveys are as effective as the conventional protocol of surveying white-winged doves only in the morning. Additional studies, using Program DISTANCE, should be conducted to similarly evaluate other species.
Management Implications:Our study revealed similar density estimates between morning and evening sampling. This similarity may be influenced, in part, by bird behavior. Both male and female white-winged doves participate in egg incubation and hatchling care (Cottam and Trefethen 1968). Females incubate eggs and care for hatchlings at night, with males roosting nearby. Males tend the nest during the majority of daytime (Schwertner et al. 2002). However, during mornings and evenings, females relieve males, allowing them to forage (Cottam and Trefethen 1968; Schwertner et al. 2002; Small et al. 2006). These two periods may overlap our morning and evening sampling times, thus maximizing the number of observations recorded for each sex. Results of our study suggest experimentation and development of more time-efficient protocols for surveying white-winged doves and other visually conspicuous avian species is warranted. State natural-resource agencies monitor certain rare, threatened, and harvested species while relying on state personnel and volunteers with time limitations. Our findings may enhance the reliability and efficiency of white-winged dove monitoring without increasing the number of sample days. Conversely, a given sampling effort could be achieved in half the time (i.e., sample days) by conducting morning and evening sampling at different localities instead of just morning sampling at one locality. Further research is needed to test our findings across ecoregions, urban habitats of varying human densities, and urban habitats of varying white-winged dove densities. In addition, more research is needed to determine whether evening sampling could be appropriate for other species. At the very least, our results suggest that, for many future small-scale autecological studies of single populations, it is worthwhile to do a pilot study to determine whether conducting surveys at different times of the day gives accurate results.
Citation:Small, M. F., J. A. Veech, and J. T. Baccus. 2012. A comparison of white-winged dove Zenaida asiatica densities estimated during morning and evening surveys. Journal of Fish and Wildlife Management 3:158-163.
Title:Alleviation of nest thermal extremes by incubating snowy plovers in the southern High Plains of Texas
Journal/Year:Wader Study Group Bulletin/2012
View:Visit Wader Study Group - Alleviation of nest thermal extremes by incubating snowy plovers in the southern High Plains of Texas
Author(s):Sarah T. Saalfeld|Warren C. Conway|David A. Haukos|William P. Johnson
Abstract:Nesting within thermally stressful environments poses many challenges for avian species, including alleviation of heat stress of both adults and eggs and synchronization of hatching. In the Southern High Plains (SHP) of Texas, Snowy Plovers Charadrius nivosus nest within a semi-arid, thermally stressful saline lake environment, where incubation temperatures and mechanisms by which Snowy Plovers alleviate thermal stress are unknown. We recorded incubation temperatures of 104 Snowy Plover nests located on saline lakes within the SHP of Texas in relation to ambient substrate (control) temperatures, month, nest success, and time during incubation. Nest temperatures mirrored control temperatures, ranging from 12.2-47.2°C, but did not exhibit the same extreme amplitude between high (day) and low (night) temperatures as controls. Wide ranging temperatures between day and night forces Snowy Plovers to be relatively plastic in incubation techniques, from heat application during night to egg cooling during day. Nest temperatures increased as the season progressed, suggesting survival and physiological benefits for Snowy Plovers to arrive and initiate egg-laying early in the season. Snowy Plovers appear to change incubation routines as nests approach hatching, potentially facilitating hatching synchronization during early morning hours (i.e. before noon). Thermal extremes experienced by nesting Snowy Plovers in the SHP of Texas necessitate adaptive behaviors to alleviate heat stress. However, habitat features (i.e. water from freshwater springs) necessary for mitigating heat stress and thermoregulation are declining within regional saline lakes that support nesting Snowy Plovers. Therefore, conservation within this region should focus on conserving freshwater springs discharging into saline lakes, the Ogallala aquifer, and the entire complex of wetlands within the SHP of Texas.
Management Implications:This study provides some baseline data on the intensity of heat stress experienced by Snowy Plovers in the SHP, evidence for survival and physiological benefits for early arrival and laying dates, and suggests a potential mechanism for hatching synchronization. Snowy Plovers in the HP nest within a hot, thermally stressful environment, necessitating incubating parents to cool eggs during daylight hours and perform adaptive behaviors to alleviate heat stress (e.g., biparental incubation, shading nests, belly soaking, standing in water, panting, and gular fluttering (Amat & Masero 2004a, Kainady & Al-Dabbagh 1976, Maclean 1975, Purdue 1976a, 1976b). However, habitat features necessary for mitigating heat stress and thermoregulation (i.e. presence of surface water for belly soaking and standing in ), as well as energy requirements (i.e. freshwater springs that support salt intolerant invertebrate prey; Andrei et al. 2009) are declining in the saline lakes that support nesting Snowy Plovers in the SHP region. Therefore conservation within this region should focus on conserving freshwater springs discharging into saline lakes, as well as the Ogallala aquifer. However, because the Ogallala aquifer is recharged from playa wetlands (Bolen et al. 1989, Osterkamp & Wood 1987), it also remains important to conserve the entire complex of wetlands within the SHP of Texas (Andrei et al. 2008, 2009).
Citation:Saalfeld, S. T., W. C. Conway, D. A. Haukos, and W. P. Johnson. 2012. Alleviation of nest thermal extremes by incubating snowy plovers in the southern High Plains of Texas. Wader Study Group Bulletin 119:77-83.
Title:An evaluation of a presence-absence survey to monitor Montezuma quail in western Texas
Journal/Year:Thesis/2012
View:Download Sanders_2012_QuailThesis.pdf
Author(s):Cristela Gonzales Sanders
Abstract:Developing an effective monitoring program for Montezuma quail (Cyrtonyx montezumae) is a challenge because the technique must be practical for surveying vast landscapes and provide reliable population trends while accounting for its low detectability. I used a presence-absence approach to estimate occupancy (i.e., proportion of sites occupied) and detection probability of Montezuma quail at Elephant Mountain Wildlife Management Area (Elephant Mountain WMA; Brewster County) and the Davis Mountains Preserve (Davis MP; Jeff Davis County) in Texas, July-August 2007 and June-August 2008. In 2008, I also sampled a Del Rio Route (DRR; Val Verde, Terrell, Pecos, and Brewster Counties) and an Uvalde Route (UVR; Uvalde, Real, Edwards, and Val Verde Counties). Four microhabitat (% bare ground, food-plant density, vegetation height, and visual obstruction) and 4 macrohabitat variables (vegetation type, elevation, aspect, and slope) were quantified at each survey point for use in development of resource-selection functions. Microhabitat points could only be sampled at Elephant Mountain WMA and Davis MP because of access. Occupancy rates were high in 2007 (Elephant Mountain WMA [95% CI: 98-100%] and Davis MP [95% CI: 94-100%]). In 2008, occupancy rates for both Elephant Mountain WMA and Davis MP ranged between [95% CI: 37%-48%]. These results indicated that surveys for Montezuma quail have to be repeated multiple times (4-5) in order to ensure at least 90% detection at a point, given a Montezuma quail is present. The survey protocol that was used in this study can help us better understand Montezuma quail populations in west Texas by determining their distribution and allowing us to establish a conservation status for Montezuma quail. Once the distribution of Montezuma quail is determined conducting yearly surveys will allow us to monitor their population distribution.
Citation:Sanders, C. G. 2012. An evaluation of a presence-absence survey to monitor Montezuma quail in western Texas. Thesis, Texas A&M University-Kingsville, USA.
Title:Breeding season demographics of a lesser prairie-chicken (Tympanuchus pallidicinctus) population in the northeastern Texas panhandle
Journal/Year:Dissertation/2012
View:Download Holt_2012_PrairieChickenDissertation.pdf
Author(s):R. Douglas Holt
Abstract:Lesser prairie-chicken (Tympanuchus pallidicinctus) populations have declined across their range since 1900 and are a candidate for listing as Threatened under the Endangered Species Act. The historic lesser prairie-chicken range included all of the Texas panhandle. Currently, lesser prairie-chickens are found in 2 distinct populations in the northeastern and southwestern Texas panhandle. I conducted a 3-year study of breeding season demographics of lesser prairie-chickens on private properties in Gray and Hemphill counties (1 March-31 August, 2008-2010). I estimated male and female breeding bird survival, nest survival, and chick survival. I used demographic data collected during this study to conduct a population viability analysis and estimate time until extinction in the northeastern Texas panhandle. I assessed the efficacy of traditional road-based lek surveys to monitor lesser prairie-chicken populations in the Rolling Plains and High Plains ecoregions of Texas. Male survival differed between seasons and age-classes. Juvenile male survival was 1.00 (SE=0.00) during the lekking season and 0.88 (SE=0.62) during the nesting season. Adult male survival was 0.51 (SE=0.10) during the lekking season and 0.82 (SE=0.08) during the nesting season. Female survival did not differ with respect to season or age and was 0.55 (SE=0.13) for the entire breeding season. Nest survival was 0.36 (SE=0.05) during my study. Chick survival was lower between hatch and 14 days post hatch (0.18; SE=0.01) than 15-63 days post-hatch (0.55; SE=0.16). Results of a population viability analysis indicated low population growth rate (λ=0.44) and time to extinction was 3.5 years under baseline conditions based on field data. Management practices resulting in higher vital rates across the annual cycle resulted in higher population growth rates and longer times until extinction. The probability of detecting an active lek during road-based lek surveys was affected by wind speed, wind direction, and ecoregion. Current assumptions of detectability of active leks are likely too great and should be adjusted based on environmental conditions. Due to the drastic reduction in lesser prairie-chicken population across their range, listing as threatened is likely. As such, it is important to collect demographic data and establish management plans for species recovery. The results of analyses based on the data collected during my study suggest that the lesser prairie-chicken population in the northeastern Texas panhandle are on the brink of extirpation.
Citation:Holt, R. D. 2012. Breeding season demographics of a lesser prairie-chicken (Tympanuchus pallidicinctus) population in the northeastern Texas panhandle. Dissertation, Texas Tech University, Lubbock, USA.
Title:Distribution and derivation of white-winged dove harvests in Texas
Journal/Year:Wildlife Society Bulletin/2012
View:Visit Wiley Online Library - Distribution and derivation of white-winged dove harvests in Texas
Author(s):Bret A. Collier|Kevin L. Skow|Shelly R. Kremer|Corey D. Mason|Robert T. Snelgrove|Kirby W. Calhoun
Keywords:band-recovery|fidelity|harvest derivation|migration|spatial distribution|Texas|white-winged dove|Zenaida asiatica
Abstract:Band recoveries provide requisite data for evaluating the spatial distribution of harvest relative to the distribution of breeding stocks for a wide variety of migratory species. We used direct and indirect band-recovery data to evaluate the distribution and derivation of harvest of white-winged doves (Zenaida asiatica) banded before hunting season in 3 distinct strata in Texas, USA, during 2007-2010. We banded 60,742 white-winged doves during 2007-2010, and based on 2,458 harvest recoveries, the majority (>95%) of white-winged dove harvest occurred during the first 2 months of the hunting season (Sep-Oct). Juvenile white-winged doves represented a greater percentage of the direct recoveries than adults across all strata (north = 80%, central = 69%, south = 82%) and the majority of direct band recoveries (north = 75%, central = 90%, south = 78%) occurred within the original banding strata. Age-specific weighting factors and harvest derivation indicated that both juvenile and adult harvest were highest within the strata of original banding. Harvest distribution data corrected for band-reporting rates indicated high fidelity of white-winged doves to specific geographic strata, with little interplay between strata. Our results suggest that population vital-rate estimates for survival and harvest for use in future Adaptive Harvest Management should focus on stock-specific levels.
Management Implications:Our study identifies distinct stocks of white-winged doves in Texas, and as such we recommend initiation of a regional banding program in Texas, New Mexico, Arizona, and California because these are the 4 states with substantial white-winged dove populations within the continental United States. Furthering our understanding of white-winged dove stocks will assist in development of a modeling framework on which to base regulatory management decisions distinct from those currently proposed for mourning doves (Otis 2004, 2006; Otis et al. 2008). Additionally, as significant breeding populations and harvest opportunities of white-winged doves occur across Mexico, we recommend that future efforts attempt to integrate white-winged dove population management in Mexico into a combined bi-national regulatory framework.
Citation:Collier, B. A., K. L. Skow, S. R. Kremer, C. D. Mason, R. T. Snelgrove, and K. W. Calhoun. 2012. Distribution and derivation of white-winged dove harvests in Texas. Wildlife Society Bulletin 36:304-312.
Title:Field assessment of the white-winged dove aging technique
Journal/Year:TPWD Final Report/2012
View:Download Fedynich_Colson_2012_AssessmentWWDOAging.pdf
Author(s):Alan Fedynich|William Colson
Abstract:Growth characteristics of eastern white-winged dove (Zenaida asiatica asiatica) nestlings are not well documented. A field study was conducted during the 2009 and 2010 breeding seasons to verify the accuracy of an aging key developed using nestlings hatched in captivity. Digital photography was used to monitor 89 wild nestlings to fledging (14 days) with partial data collected from an additional 43 nestlings. Characteristics assessed from the photographs included date of primary, secondary, tail, and dorsal feather emergence (eruption) and development of the white wing patch. The aging key developed using captive nestlings was tested on 25 wild nestlings randomly selected from those photographed, but it did not provide sufficient accuracy. Recursive partitioning was used on the wild nestling dataset to develop a classification tree from which an aging key was developed for younger aged nestlings (≤ 6 days old) and older aged nestlings (≥ 7 days old to fledging). The classification procedure could not classify to exact age those birds 2, 8, 11, 12, and 14 days old because of overlapping nestling characteristics. For nestlings ≤ 6 days old, the procedure had a 69-98% accuracy in correctly classifying nestlings within ± 1 day and 94-100% accuracy ± 2 days. As nestling age increased beyond 6 days, the classification procedure became more variable, reflecting the inability to effectively separate several age classes in older nestlings. The aging key was tested by an experienced observer (William Colson) utilizing 18 photographs of wild nestlings (1 singleton, 1 nestling pair with its nest mate digitally removed, and 1 nestling pair for each age class 1-6 days). All 18 pictures (100%) were scored to exact age. The key was then tested by 25 wildlife students using the same photos. Students exhibited high variability in accurately aging the nestlings, with the most variability occurring in correctly determining exact age (range 0-76% correct). However, students did better when placing the nestling age within ± 1 day (4-92%), ± 2 days (44-100%), and ± 3 days (60-100%), suggesting that training and or experience in aging nestlings are required when using the aging key. William Colson assessed the final version of the aging key (Part B was revised, necessitating retesting) using 280 images (10 jpg computer images of singletons and 10 jpg images of paired nestlings for each age 1-14). All 20 (100%) nestlings for ages 1, 10, and 13 were correctly aged to exact hatch date; 17 of 20 (85%) were correctly scored for ages 3, 6, and 7; and 16 of 20 (80%) for age 4. Four age classes (3, 5, 8, and 12) were the most difficult to age; however, all (100%) of these could be placed with ± 2 days of actual hatching. Overall, 10 of 14 age categories were correctly scored 100% of the time to exact age or within ± 1 day of actual hatching. Those experienced in using the key should be able to age most nestlings within ± 1 day of hatching and, for those nestlings that have extensive overlap in developmental characteristics, within ± 2 days.
Management Implications:It is apparent from our study that aging a white-winged dove nestling to the exact day is more difficult than aging within a given range of days. This results from the fact that day-to-day characteristics are often subtle making it difficult to age the nestlings separated by 1 day. Additionally, one nestling may have several diagnostic characteristics concurrently, whereas another nestling may have these same characteristics separately, thereby making it difficult to correctly age the former nestling and making it easy to age the latter nestling. Although there are some issues with the aging key because of inability to exactly age some nestlings, we believe researchers and biologists who work with white-winged doves will be able to use this key successfully. Depending on the desired level or resolution of nestling age, aging to exact age will likely not be possible for nestlings that share concurrent diagnostic characteristics of day before or day after nestlings. Expertise is an important factor in increasing the likelihood of accurately aging a nestling as demonstrated by William's ability to correctly age nestlings and minimally trained students not so well. As a way to improve the accuracy of field personnel, we recommend that the attached picture guide (Figure 6) be used as a reference to the aging key to aid in quickly narrowing down the age range after which the key can be used to separate nestlings to day. Nestlings in these photographs show specific characteristics, which are typically found for each age class. It is recommended that researchers, biologists, and their field assistants study the aging key and attached photo guide to increase their ability to accurately age wild white-winged dove nestlings. Individuals that become proficient with the aging key and the picture guide should be able to age most nestlings at least within ± 1 day of hatching and, for those nestlings that have extensive overlap of developmental characteristics, within ± 2 days.
Citation:Fedynich, A., and W. Colson. 2012. Field assessment of the white-winged dove aging technique. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Grassland bird community response to large wildfires
Journal/Year:The Wilson Journal of Ornithology/2012
View:Download Roberts_etal_2012_GrasslandBirdsWilldfire.pdf
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Author(s):Anthony J. Roberts|Clint W. Boal|David B. Wester|Sandra Rideout-Hanzak|Heather A. Whitlaw
Abstract:We studied breeding season communities of grassland birds on short-grass and mixed-grass prairie sites during the second and third breeding seasons following two large wildfires in March 2006 in the Texas panhandle, USA. There was an apparent temporary shift in avian community composition following the fires due to species-specific shifts associated with life-history traits and vegetation preferences. Species that prefer sparse vegetation and bare ground on short-grass sites, such as Horned Lark (Eremophila alpestris), benefited from wildfires, while others, such as Western Meadowlark (Sturnella neglecta), that prefer more dense vegetation, were negatively impacted. Mixed-grass sites had species specific shifts in 2007, two breeding seasons after the fires; grassland bird communities on burned plots were similar by 2008 to those on unburned plots. Avian communities appeared to return to pre-burn levels within 3 years following wildfires. Many of the responses in our study of wildfire were similar to those reported following prescribed fires elsewhere. Prescribed fires appear to have similar effects on the avian community despite differences in intensity and environmental conditions during wildfires.
Management Implications:We found an apparent temporary shift in avian community composition following wildfires due to species-specific shifts associated with life-history traits and vegetation preferences. The avian community appeared to be similar to that on unburned plots of similar grass types 3 years following the wildfires. This was consistent with vegetation recovery (Rideout-Hanzak et al. 2011). A homogeneous landscape in grasslands decreases the diversity of grassland birds (Fuhlendorf et al. 2006) and the grassland bird community reaches peak densities with increased periodic disturbance in short-grass and mixed-grass landscapes. Two of the most common species detected on short-grass plots, Grasshopper Sparrow and Horned Lark, are among 20 common North American birds experiencing the steepest population declines (Butcher and Niven 2007). The area burned by the EAC wildfires may not only provide important habitat for continued persistence of species of concern, but fire may be an integral component of habitat health for the avian community. Persistence of a diverse and abundant avian community is dependent on periodic disturbances such as wildfire or prescribed fire, grazing, and drought to provide patches of habitat in varying stages of growth after disturbance (Fuhlendorf and Engel 2001). Prescribed fire has been used to mimic wildfire effects and reduce wildfire potential (Pattison 1998). Rideout-Hanzak et al. (2011) suggest the EAC fires may not have created drastically different conditions than a prescribed fire in this ecosystem; this was corroborated by the avian community response. The wildfires may have been ecologically beneficial in providing similar services to plants and soil as historic fire regimes on the Southern High Plains. The combination of varying grazing regimes and periodic prescribed fire in the Texas panhandle would facilitate development of a mosaic of grassland patches in varying stages of recovery from disturbance, and offer a wide variety of niches for grassland birds.
Citation:Roberts, A. J., C. W. Boal, D. B. Wester, S. Rideout-Hanzak, and H. A. Whitlaw. 2012. Grassland bird community response to large wildfires. The Wilson Journal of Ornithology 124:24-30.
Title:How far is too close? Restricted, sex-biased dispersal in black-capped vireos
Journal/Year:Molecular Ecology/2012
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Author(s):Giri Athrey|Richard F. Lancce|Paul L. Leberg
Keywords:differentiation|dispersal|endangered birds|fine-scale genetic structure|fragmentation|sex-biased dispersal
Abstract:Understanding the interplay of dispersal and how it translates into gene flow is key to understanding population processes, and especially so for endangered species occupying fragmented habitats. In migratory songbirds, there is evidence that long-distance movement capabilities do not translate well into observed dispersal. Our objectives were to (i) define the fine-scale spatial genetic structure in endangered black-capped vireos to characterize dispersal patterns and (ii) to correlate dispersal dynamics to overall population genetic structure using a simulation approach. We sampled 160 individuals over 2 years to (i) describe the fine-scale genetic structuring and (ii) used this information to model scenarios to compare with actual data on change in population structuring over a 100-year interval. We found that black-capped vireos exhibit male philopatry and restricted dispersal distances, relative to females. Our simulations also support a sex-biased dispersal model. Additionally, we find that fragmentation related changes in rates of dispersal might be a likely cause for increasing levels of population structure over a 100-year period. We show that restricted sex-biased dispersal can explain population structuring in this species and that changes in dispersal rates due to fragmentation may be a continuing threat to genetic viability in this species.
Management Implications:We report on evidence for strong fine-scale genetic structuring in black-capped vireos. The short distances at which most related individuals are found suggest restricted dispersal in males of this species. Moreover, the lack of female fine-scale structure indicates that they are the dispersing sex. Simulations of the impact of dispersal scenarios on population structure agree with models of sex-biased dispersal - which correspond to observed increases in genetic differentiation in natural populations. The pattern of sex-biased dispersal observed in this species makes it susceptible to fragmentation effects on genetic structure. In view of the fragmented nature of black-capped vireo habitat, this raises concerns for the maintenance of genetic variability at the species level. Studies on other taxa indicate that habitat loss may impact species irrespective of mobility and dispersal ability (for example, see Thomas 2000). Given that sex-biased dispersal is thought to be common in many species, particularly avian species (Dale 2001; Scribner et al. 2001; Double et al. 2005), management efforts should be cognizant of the possibility that genetic differentiation may be accumulating between populations in fragmented habitats more rapidly than might be expected based on expected dispersal capabilities.
Citation:Athrey, G., R. F. Lance, and P. L. Leberg. 2012. How far is too close? Restricted, sex-biased dispersal in black-capped vireos. Molecular Ecology 21:4359-4370.
Title:Implications of coastal wetland management to nonbreeding waterbirds in Texas
Journal/Year:Wetlands/2012
View:Visit Springer Link - Implications of coastal wetland management to nonbreeding waterbirds in Texas
Author(s):Owen N. Fitzsimmons|Bart M. Ballard|M. Todd Merendino|Guy A. Baldassarre|Kevin M. Hartke
Keywords:aquatic invertebrates|marsh management|Texas coast|waterbirds
Abstract:Texas coastal marshes have declined in number and quality, prompting the widespread use of levees and water control structures to create or enhance coastal marsh habitat. In particular, management techniques that control water to provide fresh (< 0.5 ppt) and intermediate (0.5-5 ppt) marsh in a landscape dominated by brackish and saline marsh. However, research is needed to assess the effectiveness of these techniques in providing waterbird habitat. During 2007-09 along the central Texas Coast, we investigated the effects of marsh management on bird, plant, and aquatic invertebrate communities by comparing leveed areas within the coastal marsh that received water level and mechanical management, to adjacent nonmanaged marsh that received no hydrologic or mechanical manipulations. Managed marshes supported more bird species, greater waterbird densities, greater plant diversity, and greater aquatic invertebrate biomass than nonmanaged sites. However, nonmanaged wetlands supported greater densities and more species of secretive marsh birds (e.g., rails). Management of coastal marsh that reduces water salinities and suppresses plant succession appears to be a possible way to mitigate the effects of declines in fresh and intermediate marsh on nonbreeding waterbirds.
Management Implications:Our findings suggest that proper management of wetlands along the Texas coast can provide productive and diverse habitat for many wetland bird species. Greater invertebrate biomass and available energy, as well as greater seasonal variation in hydrology may have contributed to the higher bird species richness, bird diversity, and waterbird densities that we observed in managed wetlands. Marsh management techniques that reduce water salinities and suppress plant succession appear to create habitat for a suite of species that are not present in adjacent saltwater marshes. However, the value of nonmanaged marsh also was evident, as nonmanaged areas supported the majority of secretive marsh bird species (e.g., rails, bittern, sparrows) detected and greater marsh bird densities throughout the study. Future comparative studies should use extended monitoring efforts to account for broader temporal changes in plant and bird communities, and to better assess patterns across years. Also, investigating differences in foraging values of managed and nonmanaged marshes to different groups of waterbirds would help explain differences in their use, as aquatic invertebrates represent only a portion of the foods available to waterbirds in wetlands. Evaluating stopover duration, vital rates, or mass change of birds using managed and unmanaged marsh would allow a stronger assessment as to the quality of these habitats to migratory and wintering birds. Finally, major events such as hurricanes can provide valuable pre- and post event research opportunities, and future monitoring in these areas might provide clearer understanding of natural disturbances. Depending on specific objectives, managed wetlands on the Texas Coast can provide important habitat during crucial non-breeding periods to a large and diverse assemblage of birds, some of which are of high priority for conservation. Marsh management techniques present managers with an effective way to alleviate the negative effects of recent loss and degradation of freshwater and intermediate marsh on the Texas Coast (Moulton et al. 1997). The benefits of such practices are justification for the establishment of managed marshes in conjunction with the conservation of natural areas to improve habitat diversity for wetland birds at the local and landscape level on the Texas Coast.
Citation:Fitzsimmons, O. N., B. M. Ballard, M. T. Merendino, G. A. Baldassarre, and K. M. Hartke. 2012. Implications of coastal wetland management to nonbreeding waterbirds in Texas. Wetlands 32:1057-1066.
Title:Modeling the spatial and temporal dynamics of coastal marsh birds
Journal/Year:Dissertation/2012
View:Download Pickens_2012_ModelingCoastalMarshBird.pdf
Author(s):Bradley A. Pickens
Abstract:Wetland birds are likely to be influenced by habitat at multiple spatial scales, yet few studies have investigated bird responses at both broad and fine scales. Northern Gulf Coast marshes are dynamic ecosystems, and they provide an ideal place to examine habitat across spatial and temporal scales. My research focused on the secretive marsh bird guild (i.e. bitterns, rails, gallinules, grebes) with an emphasis on the king rail (Rallus elegans), a species of high conservation concern. My objectives were to investigate the wetland bird-environment relationship across scales, and to model annual changes in bird distribution. Study sites were in the fresh and intermediate (oligohaline) marshes of the Chenier Plain coastal region of southwest Louisiana and southeast Texas. I captured king rails for a two year radio telemetry study, and conducted point count surveys of marsh birds from March to mid-June of 2009-2011 using callback methods to elicit responses. I visited each point six times per year, and >100 points were surveyed each year (n=304). Localized, field-based measures (e.g. water depth), management, and broad marsh types were related to bird abundance, and species distribution models were developed for four species based on Landsat satellite imagery. Home ranges of king rails varied from 0.8-32.8 ha (n=22), rails selected for open water, and smaller home ranges were associated with greater open water within the home range (20-30%). Point counts showed fine-scale habitat models, usually incorporating water depth, were improved with the addition of broad-scale marsh type and management, classified as permanently impounded, drawdown, or unmanaged. For 11 of 12 species, a multi-scale model was better than any single spatial scale. Species distribution models showed satellite-based measures of habitat corresponded well to marsh birds as they explained 37-79% of the variation in abundance. Temporary water was the most important variable, and species' models were distinct for fresh and intermediate marshes. The spatial distribution of birds varied greatly among years, especially with migratory birds in the highly variable fresh marsh. Overall, marsh birds responded to the environment at a variety of spatial scales, and satellite-based distribution models showed broad-scale patterns and dynamic distributions among years.
Management Implications:A multi-scale perspective is essential in species' ecology (Wiens 1989), and here, I have used traditional wildlife field data combined with satellite remote sensing to gain new insights into marsh bird ecology. While predictive modeling can sometimes provide little inference, here I have shown species distribution models derived from satellite remote sensing reflected data collected on-the-ground. Furthermore, new variables, such as heterogeneity of vegetation and wetness over a 1000 m2 area were demonstrated to be important for marsh birds. Open water, and its associated edge, is usually measured in marsh bird studies, but remote sensing allowed me to distinguish between temporary and permanent open water. In fact, remote sensing models (Chapter 4) explained more variation in relative bird abundance than the field-based models (Chapter 3). From the microhabitat scale, king rails (Rallus elgans) often selected small ponds near thick vegetation, and correspondingly, the remote sensing results showed wetness heterogeneity and open water were important components of king rail habitat in intermediate marsh. In Chapter 3, I found a positive association between king rails and drawdowns in fresh marsh, and the remote sensing results showed a similar relationship via a positive correlation with temporary water in the late spring. This temporary water was often the result of water being held on the marsh, and then ponds formed while the marsh was being slowly drained. Overall, the spatially explicit modeling assisted to examine broad-scale patterns, and reemphasized the results of Chapter 3 that showed broad marsh types and management affected bird prevalence. Fundamentally, the broad context of wetland habitat affects marsh birds beyond the typical 100 m of bird survey areas. In addition to the spatial component of my study, I had several results associated with the temporal aspects of the bird-environment relationship. The effect of the 2011 drought was quantified by a decrease in adult survivorship from 90% to 60% for the breeding season. Plus, king rail chicks and juveniles were largely absent in the drought year. Complementing these data, the remote sensing research showed dramatic decreases in the predicted distribution of the king rail in fresh marsh. Other species, such as the purple gallinule (Porphyrio martinica), also showed changes in distribution due to a combination of management and weather. Future research should investigate the use of satellite remote sensing to monitor populations at broad spatial scales. Complex modeling procedures may need to be simplified with the objective of efficiently modeling at a regional scale, and the identification of indicator species could be beneficial. Feng et al. (2010) reviews the use of remote sensing for assessing ecosystem services, and they note ecologists often lack the skills to do broad-scale studies, while remote sensing experts generally do not focus on ecological questions. However, in Europe, monitoring efforts have used satellite remote sensing to identify how land use changes are predicted to effect ecosystem services, including crop production, wildlife products, habitat diversity, and recreation (Haines-Young et al. 2012). Nonetheless, the use of satellite remote sensing is only beginning to be used for species distribution modeling (Franklin 2009), and further developments are likely to be made in the coming decades.
Citation:Pickens, B. A. 2012. Modeling the spatial and temporal dynamics of coastal marsh birds. Dissertation, Louisiana State University, Baton Rouge, USA.
Title:Moist-soil managed wetlands and their associated vegetative, aquatic invertebrate, and waterfowl communities in east-central Texas
Journal/Year:Dissertation/2012
View:Download Collins_2012_MoistSoilWetlands,pdf
Author(s):Daniel P. Collins, III
Citation:Collins, D. P, III. 2012. Moist-soil managed wetlands and their associated vegetative, aquatic invertebrate, and waterfowl communities in east-central Texas. Dissertation, Stephen F. Austin State University, Nacogdoches, TX, USA.
Title:Range-wide patterns of migratory connectivity in the western sandpiper Calidris mauri
Journal/Year:Journal of Avian Biology/2012
View:Visit Wiley Online Library - Range-wide patterns of migratory connectivity in the western sandpiper Calidris mauri
Author(s):Samantha E. Franks|D. Ryan Norris|T. Kurt Kyser|Guillermo Fernandez|Birgit Schwarz|Roberto Carmona|Mark A. Colwell|Jorge Correa Sandoval|Alexey Dondua|H. River Gates|Ben Haase|David J. Hodkinson|Ariam Jimenez|Richard B. Lanctot|Brent Ortego|Brett K. Sandercock|Felicia Sanders|John Y. Takekawa|Nils Warnock|Ron C. Ydenberg|David B. Lank
Abstract:Understanding the population dynamics of migratory animals and predicting the consequences of environmental change requires knowing how populations are spatially connected between different periods of the annual cycle. We used stable isotopes to examine patterns of migratory connectivity across the range of the western sandpiper Calidris mauri. First, we developed a winter isotope basemap from stable-hydrogen (δ D), -carbon (δ 13 C), and -nitrogen (δ 15 N) isotopes of feathers grown in wintering areas. δ D and δ 15N values from wintering individuals varied with the latitude and longitude of capture location, while δ 13 C varied with longitude only. We then tested the ability of the basemap to assign known-origin individuals. Sixty percent of wintering individuals were correctly assigned to their region of origin out of seven possible regions. Finally, we estimated the winter origins of breeding and migrant individuals and compared the resulting empirical distribution against the distribution that would be expected based on patterns of winter relative abundance. For breeding birds, the distribution of winter origins differed from expected only among males in the Yukon-Kuskokwim (Y-K) Delta and Nome, Alaska. Males in the Y-K Delta originated overwhelmingly from western Mexico, while in Nome, there were fewer males from western North America and more from the Baja Peninsula than expected. An unexpectedly high proportion of migrants captured at a stopover site in the interior United States originated from eastern and southern wintering areas, while none originated from western North America. In general, we document substantial mixing between the breeding and wintering populations of both sexes, which will buffer the global population of western sandpipers from the effects of local habitat loss on both breeding and wintering grounds.
Management Implications:This study demonstrates that stable isotope analysis can be used to estimate the geographic origins of the western sandpiper, a shorebird species occurring at the interface between freshwater and marine ecosystems. However, inherent uncertainty in using stable isotopes to estimate migratory connectivity can have important consequences for modelling the population dynamics of the western sandpiper or any migratory species (Wunder and Norris 2008). It is therefore imperative that this uncertainty be quantified by modelling and incorporating potential sources of error in probability assignments, as we have done here. By obtaining a range of possible geographic origins for every individual, we allowed for uncertainty about connectivity patterns to be included in future population models, thus providing conservation managers with the ability to estimate the possible degree of change in population size that may occur as a consequence of habitat loss and/or conservation. However, even a small degree of uncertainty can influence whether models interpret population size to be increasing or declining, and detecting small population declines would therefore be difficult (Wunder and Norris 2008). Although a moderate level of connectivity exists between the population breeding in the Y-K Delta and the overwintering population in western Mexico (many individuals from western Mexico occur together in the Y-K Delta), western sandpipers generally show substantial mixing between the breeding and wintering periods, suggesting that it is unlikely that genetic population differentiation maintains latitudinal patterns of body size and age at first breeding across the wintering range. Our findings suggest that sites in the western sandpiper migratory network are unlikely to become isolated and that the global population is likely to be somewhat buffered from the effects of habitat loss or changes in population dynamics at breeding or wintering sites (Taylor and Norris 2010).
Citation:Franks, S. E., D. R. Norris, T. K. Kyser, G. Fernandez, B. Schwarz, R. Carmona, M. A. Colwell, J. C. Sandoval, A. Dondua, H. R. Gates, B. Haase, D. J. Hodkinson, A. Jimenez, R. B. Lanctot, B. Ortego, B. K. Sandercock, F. Sanders, J. Y. Takekawa, N. Warnock, R. C. Ydenberg, and D. B. Lank. 2012. Range-wide patterns of migratory connectivity in the western sandpiper Calidris mauri. Journal of Avian Biology 43:155-167.
Title:Raptor community composition in the Texas southern High Plains lesser prairie-chicken range
Journal/Year:Wildlife Society Bulletin/2012
View:Download Behney_etal_2012_RaptorCommunityLPCRange.pdf
Author(s):Adam C. Behney|Clint W. Boal|Heather A. Whitlaw|Duane R. Lucia
Keywords:anthropogenic features|community structure|conservation|lesser prairie-chicken|northern harrier|predation risk|raptor|Swainson's hawk|Tympanuchus pallidicinctus
Abstract:Predation can be a factor in preventing prey population growth and sustainability when prey populations are small and fragmented, and when predator density is unrelated to the density of the single prey species. We conducted monthly raptor surveys from February 2007 to May 2009 in adjacent areas of the Texas Southern High Plains (USA) that do and do not support lesser prairie-chickens (Tympanuchus pallidicinctus), a candidate for protection under the Endangered Species Act. During the summer period corresponding to prairie-chicken nesting and brood-rearing, Swainson's hawks (Buteo swainsoni) were the most abundant raptor. During the lekking and overwintering period, the raptor community was diverse, with northern harriers (Circus cyaneus) being the most abundant species. Raptor abundance peaked during the early autumn and was lowest during the spring. Utility poles were a significant predictor of raptor density at survey points and Swainson's hawks and all raptors, pooled, were found in greater densities in non-prairie-chicken habitat dominated by mesquite (Prosopis glandulosa). Avian predation risk on prairie-chickens, based on presence and abundance of raptors, appears to be greatest during winter when there is a more abundant and diverse raptor community, and in areas with utility poles.
Management Implications:Raptors are more likely a predation risk for lesser prairie-chickens in the Southern High Plains during the non-breeding season compared with other periods. It has been established elsewhere that prairie-chickens avoid vertical structures, and we have found that raptors were associated with such structures regardless of vegetation community in our study area. As development occurs in areas of prairie-chicken habitat, it may therefore be prudent to minimize the need for utility poles and other tall structures or seek alternative means of energy conveyance, such as buried cables. Additionally, managers and landowners may want to consider removing old utility poles that are no longer needed or in service. Swainson's hawk and overall raptor densities were higher in areas dominated by mesquite; therefore, managers may want to consider reduction of mesquite cover. Such efforts would likely reduce the general presence of raptors plus potentially increase habitat suitability and occupiable space for lesser prairie-chickens.
Citation:Behney, A. C., C. W. Boal, H. A. Whitlaw, and D. R. Lucia. 2012. Raptor community composition in the Texas southern High Plains lesser prairie-chicken range. Wildlife Society Bulletin 36:291-296.
Title:Relationship of lesser-prairie chicken density to landscape characteristics in Texas
Journal/Year:Thesis/2012
View:Download Timmer_2012_LPCThesis.pdf
Author(s):Jennifer M. Timmer
Abstract:Ground-based lek surveys have traditionally been used to index trends in prairie grouse populations (Centrocercus and Tympanuchus spp.). However, indices of abundance or density can be fundamentally flawed and techniques that account for incomplete detection should be used. Distance sampling is a common technique used to estimate the density and abundance of animal populations and has been used with aerial surveys to monitor avian populations. With an increase in renewable energy development in native prairies and sagebrush steppe, there is a greater need to effectively monitor prairie grouse populations. One such species, the lesser prairie-chicken (LPC; T. pallidicinctus), has faced significant population declines and is thus, a species of conservation concern. In addition, much of the current and proposed wind energy development in the Great Plains overlaps some of the extant LPC distribution and few peer-reviewed studies have been conducted to investigate this potential disturbance to LPCs. Hierarchical distance sampling models can relate LPC lek density to landscape features and help predict the potential impact from wind and other energy development on lek density. Thus, the main objectives of our study were to estimate lek density in our sampling frame and to model anthropogenic and landscape features associated with lek density. We accomplished this by flying helicopter lek surveys for 2 field seasons and employing an aerial line-transect method developed at Texas Tech University. We inventoried 208, 7.2 km X 7.2 km survey blocks and detected 71 new leks, 25 known leks, and observed 5 detections outside the current LPC range. We estimated 2.0 leks/100 km2 (90% CI = 1.4-2.7 leks/100 km2) and 12.3 LPCs/100 km2 (90% CI = 8.5-17.9 LPCs/100 km2) for our sampling frame. Our state-wide abundance estimates were 293.6 leks (90% CI = 213.9-403.0 leks) and 1,822.4 LPCs (90% CI = 1,253.7-2,649.1 LPCs). Our best model indicated lek size and lek type (wi = 0.235) influenced lek detectability. Lek detectability was greater for larger leks and natural leks rather than man-made leks. We used hierarchical distance sampling to build spatially-explicit models of lek density and landscape features. Our most competitive model included percent shrubland + paved road density + unpaved road density (AIC = 938.926, wi = 0.826). Based on the spatially-explicit model, we estimated 248.5 leks (cv = 0.136) for our sampling frame. Lek density peaked when ≈ 50% of the landscape was composed of shrubland patches (i.e., shrubs < 5 m tall comprising ≥ 20% of the total vegetation). This model also indicated an inverse relationship between lek density and paved and unpaved road densities. Our state-wide survey efforts provide wildlife managers and biologists with population estimates, new lek locations, and indicate landscape features that are related to lek density. Our spatially-explicit models predicted lek density based on percent shrubland and paved and unpaved road densities which can be used to predict how lek density may change in response to changes in habitat conditions and road densities.
Management Implications:Species of conservation concern, such as LPCs, require effective monitoring and management efforts. Aerial lek surveys can provide wildlife managers and biologists with accurate density and abundance estimates and distribution information. For example, the 2 CREZs in the Texas Panhandle overlap low-density portions of the LPC range, but overall LPC abundance in Texas is lower than previously thought. Wind energy developers and biologists can utilize our techniques to identify and monitor LPC populations that occur in potential wind resource areas. They can also avoid energy development in high-density portions of the LPC range. Our study provides an initial encounter rate and detection probability that can be used to determine the required transect length and expected number of detections, given a desired level of precision (Buckland et al. 2001). The amount of transects needed for a desired level of precision or expected number of detections may determine if aerial lek surveys are even a feasible and cost-effective management tool. Based on our spatial analysis, wildlife managers should strive to maintain ≈ 50% of the landscape as shrubland patches for higher LPC lek densities in Texas. This can be achieved through habitat management techniques, such as prescribed burns or light grazing, which create a heterogeneous habitat of shrubs, grasses, and forbs (Applegate and Riley 1998, Bell et al. 2010). Our greatest predicted lek density estimates occurred in Gray, Hemphill, and Lipscomb counties in the northeast Panhandle and Bailey, Cochran, and Yoakum counties in the southwest Panhandle (Fig. 3.2; Appendix C). Given that most of our lek detections also occurred in these counties (Fig. 3.2; Appendix C), the construction or frequent use of roads for agriculture, oil or natural gas development, or other purposes, should be avoided in these areas to reduce negative impacts on LPCs. The construction of transmission lines for energy development should also be avoided in these areas. Regions in which predicted lek density is low (e.g., Carson county) may be better suited for energy development if it is imminent within the Texas occupied range or habitat improvement projects to satisfy LPC management objectives. Biologists, wildlife managers, and energy developers can also use our spatial models to predict how lek density may change in response to habitat management strategies or activities promoting the construction or use of roads within the Texas occupied range. This information will be necessary if LPCs are listed on the ESA. Another logical application of our spatial models would be to predict lek density outside the Texas occupied range to give wildlife managers an indication of other areas that could be targeted for LPC surveys or conservation efforts. However, our models should not be used to predict absolute density outside of our sampling frame.
Citation:Timmer, J. M. 2012. Relationship of lesser-prairie chicken density to landscape characteristics in Texas. Thesis, Texas Tech University, Lubbock, USA.
Title:Sexual selection and mating chronology of lesser prairie-chickens
Journal/Year:The Wilson Journal of Ornithology/2012
View:Download Behney_etal_2012_SelectionMatingLPC.pdf
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Author(s):Adam C. Behney|Blake A. Grisham|Clint W. Boal|Heather A. Whitlaw|David A. Haukos
Abstract:Little is known about mate selection and lek dynamics of Lesser Prairie-Chickens (Tympanuchus pallidicinctus). We collected data on male territory size and location on leks, behavior, and morphological characteristics and assessed the importance of these variables on male Lesser Prairie-Chicken mating success during spring 2008 and 2009 in the Texas Southern High Plains. We used discrete choice models and found that males that were less idle were chosen more often for mating. Our results also suggest that males with smaller territories obtained more copulations. Morphological characteristics were weaker predictors of male mating success. Peak female attendance at leks occurred during the 1-week interval starting 13 April during both years of study. Male prairie-chickens appear to make exploratory movements to, and from, leks early in the lekking season; 13 of 19 males banded early (23 Feb-13 Mar) in the lekking season departed the lek of capture and were not reobserved (11 yearlings, 2 adults). Thirty-three percent (range = 26-51%) of males on a lek mated (yearlings = 44%, adults = 20%) and males that were more active experienced greater mating success.
Citation:Behney, A. C., B. A. Grisham, C. W. Boal, H. A. Whitlaw, and D. A. Haukos. 2012. Sexual selection and mating chronology of lesser prairie-chickens. The Wilson Journal of Ornithology 124:96-105.
Title:Snowy plover nest site selection, spatial patterning, and temperatures in the southern High Plains of Texas
Journal/Year:Journal of Wildlife Management/2012
View:Visit Wiley Online Library - Snowy plover nest site selection, spatial patterning, and temperatures in the southern High Plains of Texas
Author(s):Sarah T. Saalfeld|Warren C. Conway|David A. Haukos|William P. Johnson
Keywords:Charadrius nivosus|logistic regression|nesting|nest site selection|nest temperature|saline lake|snowy plover|Southern High Plains of Texas|surface water
Abstract:Snowy plover (Chadrius nivosus) populations have declined throughout their range, in part because of habitat degradation and poor nest success, making information regarding regionally specific nest site selection and spatial patterns important when considering habitat conservation and management guidelines. We determined nest site selection characteristics (n = 180) and examined spatial patterns (n = 215) of snowy plover nests in saline lakes in the Southern High Plains (SHP) of Texas. At 104 nests, we examined the influence of substrate type on nest temperatures and heat mitigation. Snowy plover nests were more likely to be found near an object, on pebble substrate, and with fewer plants than random sites. High use areas were generally located in areas with pebble substrate and on human-made or natural islands, berms, and peninsulas. Overall, nests placed on pebble substrate had lower temperatures during the day than nests placed on sand substrates. Nest placement on pebble substrate may be valuable to nesting snowy plovers, providing thermal advantages to incubating adults and depressing potentially high nest predation rates. Management guidelines for this region should emphasize the importance of addressing key elements of snowy plover nesting habitat including the presence of pebble substrate and reducing vegetation encroachment.
Management Implications:The use of pebble substrates for nesting snowy plovers in the SHP of Texas provides thermoregulatory benefits during incubation. Habitat enhancement through substrate modification (i.e. restoring pebble substrate areas lost to sand deposition) could be explored as a means to maintain current nesting habitat, as well as reduce thermal stress to incubating adults. As current land use practices surrounding saline lakes (e.g. agriculture, mining, development, etc.) can affect both wind and water erosion rates, conservation guidelines for this region should focus on landowner incentives (e.g., U.S. Department of Agriculture Conservation Reserve Program) to maintain vegetation in surrounding uplands that could decrease sedimentation of saline lakes. However, as vegetation encroachment may have serious impacts to nesting snowy plovers, maintaining natural fire regimes within vegetated upland areas may reduce vegetation encroachment on saline lakes within this area. Furthermore, flooding events may decrease vegetation growth on saline lakes (Faanes 1983); however, these events depend on unpredictable weather as well as surface flow and groundwater seepage.
Citation:Saalfeld, S. T., W. C. Conway, D. A. Haukos, and W. P. Johnson. 2012. Snowy plover nest site selection, spatial patterning, and temperatures in the southern High Plains of Texas. Journal of Wildlife Management 76:1703-1711.
Title:Spatial and temporal variations in the dispersal rates of white-winged doves
Journal/Year:TPWD Final Report/2012
View:Download Butcher_etal_2012_WWDODispersal.pdf
Author(s):Jerrod A. Butcher|Bret A. Collier|Jay A. Roberson|Nova J. Silvy|Markus J. Peterson
Keywords:introduced|invasive|dispersal rate|population|range expansion|spatial|velocity of spread|white-winged doves|Zenaida asiatica
Abstract:We examined spatial and temporal patterns of range expansion of white-winged doves along the northern edge of their geographical range from 1979 to 2007, while accounting for imperfect detection. We developed a model that aided us in predicting when and where white-winged doves would be found in the future. Our study covered the southern half of the United States. We developed spatial expansion models of white-winged doves using data from North American Breeding Bird Surveys (BBS). Variables used to model spatial variation in expansion included distance from initial population center, area of urban land cover, and ecoregion. We used robust design occupancy analysis to predict expansion of white-winged doves, Akaike's Information Criterion to rank potential models, and compared and estimated parameters using PRESENCE 4.2. We evaluated models by comparing predictions to actual observations in 1991 and 2007 using the area under the curve (AUC) of a receiver-operating characteristic (ROC) plot. The best model from our set estimated occupancy on distance from initial population; held colonization constant between 1979 and 1991; estimated colonization from 1993 to 2007 on distance from initial population, ecoregion, and urban land cover; estimated local extinction on distance from initial population; and estimated probability of detection on ecoregion and urban land cover. In 1991, our model was an excellent predictor for detecting white-winged doves (AUC = 0.979). In 2007, our model was a useful predictor (AUC = 0.824). Predicting occurrence of white-winged doves can be completed effectively using BBS data when one accounts for imperfect detection. Accounting for imperfect detection allowed us to use a nationwide, readily-available, long-term survey to accurately model spatial expansion of white-winged doves. Our novel approach of treating each BBS route as independent secondary survey within the primary sample periods allowed us to account for imperfect detection.
Management Implications:Estimated predictions of when and where white-winged doves are likely to be found can be determined with our model. Knowing when and where to survey for white-winged doves could allow biologists to efficiently survey white-winged doves, use optimal impact design studies to determine the effects of the encroachment of a white-winged doves into an area (Green, 1979; Cassey, 2005), and assess potential risks to native biota (Johnson et al., 2001; Wittenberg & Cock, 2001; Arriaga et al., 2004).
Citation:Butcher, J. A., B. A. Collier, J. A. Roberson, N. J. Silvy, and M. J. Peterson. 2012. Spatial and temporal variations in the dispersal rates of white-winged doves. Texas Parks and Wildlife Department Final Report, Austin, USA.
Title:Survival, fidelity, and recovery rates of white-winged doves in Texas
Journal/Year:Journal of Wildlife Management/2012
View:Visit Wiley Library Online - Survival, fidelity, and recovery rates of white-winged doves in Texas
Author(s):Bret A. Collier|Shelly R. Kremer|Corey D. Mason|Markus J. Peterson|Kirby W. Calhoun
Keywords:banding|harvest|multi-state capture recapture|site fidelity|survival|recovery rates|Texas|white-winged dove|Zenaida asiatica
Abstract:Management of migratory birds at the national level has historically relied on regulatory boundaries for definition of harvest restrictions and estimation of demographic parameters. Most species of migratory game birds are not expanding their ranges, so migratory corridors are approximately fixed. White-winged doves (Zenaida asiatica), however, have undergone significant variation in population structure with marked range expansion occurring in Texas, and range contraction in Arizona, during the last 30 years. Because >85% of white-winged dove harvest in the United States (approx. 1.3 million annually) now occurs in Texas, information on vital rates of expanding white-winged dove populations is necessary for informed management. We used band recovery and mark-recapture data to investigate variation in survival and harvest across 3 geographic strata for white-winged doves banded in the pre-hunting season in Texas during 2007-2010. We banded 60,742 white-winged doves, recovered 2,458 bands via harvest reporting, and recaptured 455 known-age birds between 2007 and 2010. The best supporting model found some evidence for geographic differences in survival rates among strata (A-C) in both hatch-year (juvenile; A = 0.205 [SE = 0.0476], B = 0.213 [SE = 0.0278], C = 0.364 [SE = 0.0254]) and after-hatch year (adult; A = 0.483 [SE = 0.0775], B = 0.465 [SE = 0.0366], C = 0.538 [SE = 0.251]) birds. White-winged doves had a low probability of moving among strata (0.009) or being recaptured (0.002) across all strata. Harvest recovery rates were concordant with estimates for other dove species, but were variable across geographic strata. Based on our results, harvest management strategies for white-winged doves in Texas and elsewhere should consider differences in population vital rates among geographic strata.
Management Implications:Our results provide demographic estimates for use in development of mechanistic population models that may in turn be used to inform harvest management decisions in Texas and possibly elsewhere. Assuming that white-winged dove populations exhibit vital rates that also are geographically specific, one implication of our research is that once identified, these geographic areas can be used to facilitate and inform banding programs for white-winged doves across the southwestern United States as outlined by Rabe and Sanders (2010). Additionally, until a national banding program for white-winged doves is implemented across the United States, our recovery rate estimates could be combined with age-specific harvest information collected via a parts collection survey for recruitment monitoring to inform population management actions (Nichols and Tomlinson 1993). Finally, ongoing development of harvest management strategies for white-winged doves should focus on evaluating which geographic delineations are appropriate for harvest management planning as white-winged doves exist in a host of available habitats across the southwestern United States.
Citation:Collier, B. A., S. R. Kremer, C. D. Mason, M. J. Peterson, and K. W. Calhoun. 2012. Survival, fidelity, and recovery rates of white-winged doves in Texas. Journal of Wildlife Management 76:1129-1134.
Title:The impacts of three common mesopredators on the reintroduced population of eastern wild turkeys in Texas
Journal/Year:Dissertation/2012
View:Download Melville_2012_MesopredatorWildTurkey.pdf
Author(s):Haemish Ian Melville
Abstract:Early in the 20th century wild turkeys (Meleagis gallopavo) in North America were on the brink of extinction. Conservation and reintroduction efforts ensured that this species recovered throughout most of its historic range. Efforts to reintroduce eastern wild turkeys (Meleagris gallopavo sylvestris) to the Pineywoods of east Texas have achieved limited success. Previous research suggested that predation may have confounded this reintroduction. My aim was to quantify the influence of mesopredators on the wild turkey population in the Pineywoods. Raccoons (Procyon lotor), bobcats (Lynx rufus) and coyotes (Canis latrans) occur sympatrically in east Texas and are thought to prey on wild turkeys, their nests and poults. I fitted bobcats, coyotes and raccoons with both GPS and VHF collars. I used location data and GIS applications to estimate home ranges, home range overlap and habitat selection for the mesopredators. I used scat analysis to determine the diet of mesopredators and to establish whether they preyed on wild turkeys. I used capture mark recapture (CMR) techniques to investigate small mammal population dynamics. I analyzed the CMR data on an annual and seasonal basis. I used spotlight counts and track plates to assess the seasonal relative abundance of eastern cottontail rabbits (Sylvilagus floridana). I used artificial nests to identify likely nest predators of wild turkey nests. I found that mesopredators in the Pineywoods had larger home ranges than elsewhere in the southeast. Bobcat and coyote home ranges varied seasonally, being largest in summer and fall respectively. Raccoon home ranges did not vary seasonally. Bobcats and coyotes shared space more than did raccoons with bobcats or coyotes. There was differential habitat selection between species, but mature pine and young pine were important to the mesopredators and as nesting habitat for eastern wild turkeys. I found no wild turkey remains in scat samples. White tailed deer (Odocoileus virginianus), lagomorphs and small mammals occurred in the diets of all three mesopredators. Small mammal numbers varied seasonally, declining from spring to summer, in synchrony with mesopredator diet diversification, and wild turkey nesting and brood rearing. Lagomorph abundance did not vary seasonally. Bobcats were predominantly carnivorous while coyotes and raccoons were omnivorous, consuming seasonal fruit and insects. American crows (Corvus brachyrhynchos) and raccoons were the primary artificial nest predators. Crows depredated most artificial nests, except in summer, when raccoons depredated the most nests. I concluded that the impact of mesopredators on wild turkeys was not as severe as suggested by previous research. I suggested a combination of video monitoring live wild turkey nests to identify nest predators, improvement of nesting habitat to reduce mesopredator / wild turkey nest encounters, and a program of conditioned taste aversion to reduce any nest predation by mesopredators.
Citation:Melville, H. I. 2012. The impacts of three common mesopredators on the reintroduced population of eastern wild turkeys in Texas. Dissertation, Texas A&M University, College Station, USA.
Title:Grassland bird response to patch burn-grazing in a sand sagebrush-mesquite rangeland
Journal/Year:Thesis/2012
View:Download Yancey_2013_BirdThesis.pdf
Author(s):Sean R. Yancey
Citation:Yancey, S. R. 2013. Grassland bird response to patch burn-grazing in a sand sagebrush-mesquite rangeland. Thesis, Texas Tech University, Lubbock, USA.
Title:Immigration and recruitment in an urban white-winged dove breeding colony
Journal/Year:Journal of Fish and Wildlife Management/2013
View:Download Collier_etal_2013_ImmigrationRecruitmentWWDO.pdf
Author(s):Bret A. Collier|Shelly R. Kremer|Corey D. Mason|J. Stone|Kirby W. Calhoun|Markus J. Peterson
Keywords:capture-recapture|Jolly-Seber|recruitment|white-winged dove
Abstract:Dove population management necessitates estimates of vital rates for use in mechanistic models used to evaluate and predict population responses to environmental variation and/or alternative harvest scenarios. Estimating recruitment (number of juveniles per adult) is complicated because a compendium of factors drives production in doves. White-winged doves Zenaida asiatica exhibit a fairly unique breeding strategy wherein they commonly return to the same breeding area and reproduce in large breeding aggregations (i.e., colonies). We used an open-population capture-recapture model to estimate annual immigration and in situ recruitment of white-winged doves breeding in an urban colony during 2009 and 2010. We captured 5,101 unique white-winged doves in 2009 (2,894 after hatch year, 2,207 hatch year) and 3,502 unique white-winged doves in 2010 (3,106 after hatch year, 486 hatch year). Immigration of adults into the breeding colony peaked during late April and early May, with in situ recruitment occurring during a 6-wk period from 19 June to 30 July. Our results predicted that >90% of all hatch-year individuals had entered the local population by 1 August. The Jolly-Seber model used allows white-winged dove recruitment values to be estimated directly (rather than as a conglomerate of multiple parameters), separates immigration from in situ recruitment within a season, and can be useful for monitoring recruitment and evaluating alternative recruitment indices for future use in harvest management-planning actions.
Management Implications:Admittedly, although our intensive capture-recapture data were necessary for initial evaluation of immigration and breeding-season timing of white-winged doves, our approach is likely not tenable for long-term studies of white-winged dove recruitment. However, our results do provide a foundation for us to suggest an alternative monitoring protocol for white-winged dove recruitment in Texas. Previous work on timing of breeding activity indexed via coo counts (Sepulveda et al. 2006) indicated that peaks of calling occurred in early May, which from our data would be concordant with our estimates of reproductive timing. Managers in urban areas could conduct point-count sample surveys (Buckland 2006) of the breeding population during mid-May to estimate after-hatch-year population size, and then repeat the survey in late July or early August to estimate abundance when a majority of hatch-year birds have entered the local population but before migration occurs. Then, straightforward application of a population growth estimator (λ = Nt+1/Nt) based on the point counts could be used to estimate a recruitment rate (λ population growth), which in theory should be concordant with in situ annual recruitment rates. Because white-winged doves have transitioned to urban environments (Schwertner and Johnson 2005; Collier et al. 2012a, 2012b), our information on the timing of adult immigration and in situ recruitment could make the estimation of recruitment via count statistics a plausible, logistically feasible option for supporting future conservation and harvest-management planning strategies. We acknowledge that like most intensive studies, our work is limited in both scope and scale, and thus any application for harvest management planning should be approached cautiously until further similar studies are conducted. However, the immigration timing and recruitment information we collected should provide a useful comparison with recruitment estimates garnered via the USFWS Parts Collection Survey currently under development for use in supporting better management of white-winged doves.
Citation:Collier B. A., S. R. Kremer, C. D. Mason, J. Stone, K. W. Calhoun, and M. J. Peterson. 2013. Immigration and recruitment in an urban white-winged dove breeding colony. Journal of Fish and Wildlife Management 4:33-40.
Title:Recent declines in apparent survival and survey counts of snowy plovers breeding in the southern High Plains of Texas
Journal/Year:The Wilson Journal of Ornithology/2013
View:Download Saalfeld_etal_2013_DeclinesSnowyPlover.pdf
Author(s):Sarah T. Saalfeld|Warren C. Conway|David A. Haukos|William P. Johnson
Keywords:apparent survival|Charadrius nivosus|Cormack-Jolly-Seber|demographics|saline lakes|Southern High Plains|Texas
Abstract:We quantified changes in long-term Snowy Plover (Charadrius nivosus) survey counts and return rates, estimated current sex and age-specific apparent survival and encounter rates, and calculated recruitment thresholds needed to maintain a stable population in the Southern High Plains of Texas. Mean survey counts of adult Snowy Plovers decreased by 78% at one saline lake (from 80 adults/survey to 18 adults/survey) from 1999-2000 to 2008-2010 but remained consistent at an alternate lake (from 45 adults/survey to 41 adults/survey). Adult and juvenile return rates have similarly declined within this time frame by 25 and 62%, respectively. Long-term declines in return rates may be the result of increased mortality from declining habitat conditions either within or outside the breeding season. Current estimates of adult (65%) and juvenile (12%) apparent survival are lower than most other estimates for Snowy Plovers throughout their range. Current estimates of adult and juvenile apparent survival and return rates indicate 5.8-10.0 hatchlings per adult per year are needed to maintain the current population without immigration, a 3-5 fold increase in the past 10 years.
Management Implications:Current conservation actions for Snowy Plovers typically focus on increasing nest success (e.g., predator exclosures, predator control, and reduction of human disturbance around nest sites; Page et al. 2009), which cannot reverse current rates of adult and juvenile mortality. Conservation efforts must focus on increasing adult and juvenile survival on both breeding and wintering areas. Techniques for improving adult and juvenile survival are lacking, exacerbating this problem for regional Snowy Plover populations. It remains important to conserve saline lake habitat, especially freshwater springs discharging into saline lakes. Retiring irrigation wells in the vicinity of saline lakes could be explored to maintain and/or increase groundwater levels and subsequent spring activity. The Ogallala Aquifer is recharged by playa wetlands (Osterkamp and Wood 1987, Bolen et al. 1989) and it remains important to conserve the entire complex of wetlands within the Southern High Plains of Texas (Andrei et al. 2008).
Citation:Saalfeld, S., W. C. Conway, D. A. Haukos, and W. P. Johnson. 2013. Recent declines in apparent survival and survey counts of snowy plovers breeding in the southern High Plains of Texas. The Wilson Journal of Ornithology 125:79-87.
Title:Seasonal variation in offspring sex ratio in the snowy plover
Journal/Year:Western North American Naturalist/2013
View:Visit Western North American Naturalist - Seasonal variation in offspring sex ratio in the snowy plover
Author(s):Sarah T. Saalfeld|Warren C. Conway|David A. Haukos|William P. Johnson
Abstract:The Snowy Plover (Charadrius nivosus) is unique in being a determinate layer of an odd modal clutch size and in having a variable mating system in which the female brood desertion occurs regularly. These traits make determining Snowy Plover offspring sex ratios important not only for long-term population stability, as the species is of conservation concern, but also for application to sex allocation theory. In this study, we determined Snowy Plover offspring sex ratios, examined differential costs of producing male and female offspring, and evaluated sex ratio variation in relation to maternal condition, habitat condition, and time during the nesting season on saline lakes of the Southern High Plains of Texas. Examination of 245 chicks from 118 clutches during 1999-2000 and 2008-2009 showed that male offspring were more costly to produce than female offspring; however, offspring sex ratio did not differ from parity, but was slightly male-biased in most years. The probability of producing a male offspring was greater both earlier and later in the breeding season than in the middle. As the availability of saline lake surface water and the subsequent availability of food vary unpredictably throughout the breeding season, depending on precipitation events, we suggest that sex ratio adjustment in unpredictable environments may not be straightforward and may follow nonlinear models and/or vary annually. The effects such changes in sex ratio may have on population growth and stability remain unknown.
Management Implications:Within the SHP of Texas, Snowy Plover populations have declined within the past 10 years (Saalfeld et al. 2013), clearly highlighting the need for regional conservation efforts. For conservation to be successful, understanding the current dynamics influencing population growth, such as population size, mortality rates, recruitment rates, and sex ratios, remains important. This population appears to have seasonal shifts in offspring sex ratios, and these shifts may be related to female condition as well as to differential advantages of sexes being born at specific times. Currently, the mechanism for seasonal variation in sex ratios remains unknown (Krackow 1995, Pike and Petrie 2003, Alonso-Alvarez 2006), as well as the effects such changes may have on population growth and stability. One of the primary conservation concerns within this region is surface water availability in saline lakes (Saalfeld 2010), where declining spring flow due to decreasing water table levels of the aquifer has occurred since the 1950s (Brune 2002). This decline, which has been driven by groundwater pumping for row-crop irrigation in the most intensively agriculturalized regions in North America (Bolen et al. 1989), has shortened saline lake hydroperiods and increased surface water salinity. Because freshwater springs not only provide reliable surface water during the breeding season, a necessary landscape feature for nesting Snowy Plovers (Conway et al. 2005b), but also support salt-intolerant invertebrate prey (Andrei et al. 2009), declining spring flow may decrease suitability of saline lakes for nesting shorebirds, as well as decrease food availability during the nesting season, resulting in poor condition of nesting individuals. Long-term reduction in food availability and subsequent poor condition of nesting females may result in significant changes in offspring sex ratios (Cooch et al. 1997). Because females in poor condition are likely to produce more females (Trivers and Willard 1973), if conditions continue to decline within this region, sex ratios may become more female-biased, having potentially dramatic effects on population growth and stability. Therefore, it remains important to provide high-quality habitat for nesting Snowy Plovers in the SHP of Texas. As surface water availability is the main factor influencing regional saline lake habitat quality, conserving the Ogallala aquifer and associated freshwater artesian springs discharging into saline lakes will stand to improve surface water availability and habitat quality. However, because the Ogallala aquifer is recharged from playa wetlands (Osterkamp and Wood 1987, Bolen et al. 1989), it also remains important to conserve the entire complex of wetlands within the SHP of Texas (Andrei et al. 2008, 2009).
Citation:Saalfeld, S. T., W. C. Conway, D. A. Haukos, and W. P. Johnson. 2013. Seasonal variation in offspring sex ratio in the snowy plover. Western North American Naturalist 73:60-71.
Title:Interspecific hybridization contributes to high genetic diversity and apparent effective population size in an endemic population of mottled ducks (Anas fulvigula maculosa)
Journal/Year:Conservation Genetics/2014
View:Visit Springer Link - Interspecific hybridization contributes to high genetic diversity and apparent effective population size in an endemic population of mottled ducks (Anas fulvigula maculosa)
Author(s):Jeffrey L. Peters|Sarah A. Sonsthagen|Philip Lavretsky|Michael Rezsutek|William P. Johnson|Kevin G. McCracken
Keywords:coalescent|phenotype|introgression|population structure|multilocus phylogeography|mtDNA|introns
Abstract:Under drift-mutation equilibrium, genetic diversity is expected to be correlated with effective population size (Ne). Changes in population size and gene flow are two important processes that can cause populations to deviate from this expected relationship. In this study, we used DNA sequences from size independent loci to examine the influence of these processes on standing genetic diversity in endemic mottled ducks (Anas fulvigula) and geographically widespread mallards (A. platyrhynchos), two species known to hybridize. Mottled ducks have an estimated census size that is about two orders-of-magnitude smaller than that of mallards, yet these two species have similar levels of genetic diversity, especially at nuclear DNA. Coalescent analyses suggest that a population expansion in the mallard at least partly explains this discrepancy, but the mottled duck harbors higher genetic diversity and apparent Ne than expected for its census size even after accounting for a population decline. Incorporating gene flow into the model, however, reduced the estimated Ne of mottled ducks to 33% of the equilibrium Ne and yielded an estimated Ne consistent with census size. We also examined the utility of these loci to distinguish among mallards, mottled ducks, and their hybrids. Most putatively pure individuals were correctly assigned to species, but the power for detecting hybrids was low. Although hybridization with mallards potentially poses a conservation threat to mottled ducks by creating a risk of extinction by hybridization, introgression of mallard alleles has helped maintain high genetic diversity in mottled ducks and might be important for the adaptability and survival of this species.
Management Implications:DNA sequences from six independent loci sampled from WGC mottle ducks and North American mallards revealed two primary findings relevant to future conservation and management of mottled ducks. First, despite large differences in North American census sizes (135,000 mottled ducks versus 9,330,000 mallards), these two species had similar levels of genetic diversity, especially at nuDNA. Coalescent analyses suggested that gene flow from mallards into mottled ducks (and to a lesser extent, shared ancestry) explains the higher-than-expected genetic diversity in mottled ducks. Second, mottled ducks and mallards share many genetic polymorphisms but are sufficiently differentiated in allele frequencies to allow species identification. However, the six loci examined here seem to offer low power for detecting hybrids. Given generally weak allelic frequency differences across nuclear loci, monitoring hybridization using molecular methods and evaluating the utility of plumage characteristics for hybrid identification will require many markers. New techniques in next-generation sequencing will likely offer high power for detecting those loci important in the species integrity of mottled ducks and for use as a monitoring tool for conservation. Although some level of hybridization might be beneficial, our results demonstrate that hybridization with mallards is a phenomenon that should be studied more closely in WGC mottled ducks, and that continued monitoring of phenotypic and genotypic characters is important to determine the frequency and spatial extent of hybridization.
Citation:Peters, J. L., S. A. Sonsthagen, P. Lavretsky, M. Rezsutek, W. P. Johnson, and K. G. McCracken. 2014. Interspecific hybridization contributes to high genetic diversity and apparent effective population size in an endemic population of mottled ducks (Anas fulvigula maculosa). Conservation Genetics 15:509-520.
Title:Linking multi-temporal satellite imagery to coastal wetland dynamics and bird distribution
Journal/Year:Ecological Modeling/2014
View:Visit Science Direct - Linking multi-temporal satellite imagery to coastal wetland dynamics and bird distribution
Author(s):Bradley A. Pickens|Sammy L. King
Keywords:coastal marsh|MARS|model transferability|remote sensing|species distribution model|waterbirds
Abstract:Ecosystems are characterized by dynamic ecological processes, such as flooding and fires, but spatial models are often limited to a single measurement in time. The characterization of direct, finescale processes affecting animals is potentially valuable for management applications, but these are difficult to quantify over broad extents. Direct predictors are also expected to improve transferability of models beyond the area of study. Here, we investigated the ability of nonstatic and multitemporal habitat characteristics to predict marsh bird distributions, while testing model generality and transferability between two coastal habitats. Distribution models were developed for king rail (Rallus elegans), common gallinule (Gallinula galeata), least bittern (Ixobrychus exilis), and purple gallinule (Porphyrio martinica) in fresh and intermediate marsh types in the northern Gulf Coast of Louisiana and Texas, USA. For model development, repeated point count surveys of marsh birds were conducted from 2009 to 2011. Landsat satellite imagery was used to quantify both annual conditions and cumulative, multitemporal habitat characteristics. We used multivariate adaptive regression splines to quantify bird-habitat relationships for fresh, intermediate, and combined marsh habitats. Multitemporal habitat characteristics ranked as more important than single-date characteristics, as temporary water was most influential in six of eight models. Predictive power was greater for marsh type-specific models compared to general models and model transferability was poor. Birds in fresh marsh selected for annual habitat characterizations, while birds in intermediate marsh selected for cumulative wetness and heterogeneity. Our findings emphasize that dynamic ecological processes can affect species distribution and species-habitat relationships may differ with dominant landscape characteristics.
Management Implications:In conclusion, marsh birds commonly selected multitemporal habitat characteristics which represented the complex process of flooding over space and time. Due to the worldwide importance of wetlands (Mitsch and Gosselink, 2007), and other dynamic ecosystems, multitemporal characteristics could be useful for identifying both species' distribution and habitat relationships across many taxa. While SDMs have a history of identifying priority areas for conservation (Faleiro et al., 2013; Wilson et al., 2005), our nonstatic models can monitor changes over time and inform management at a relatively finescale (100 m). For example, habitat could be identified and improved for king rail by changing permanent water to temporary water in fresh marshes, and the change could be monitored. While a few species-habitat relationships were difficult to interpret (Fig. 4 - SDT; Fig. 6 - spring NDVI), the vast majority provided ecologically meaningful results that can be applied to the management of wetland species. Additionally, we have shown that models transferred within the same geographic region may still perform poorly due to differing abiotic differences of the ecosystem. The specificity of the models suggest that differing wetland processes, such as regular tidal flooding not experienced in this study, will limit a model's applicability. In these cases, developing distinct SDMs for specific habitat types can optimize model precision.
Citation:Pickens, B. A., and S. L. King. 2014. Linking multi-temporal satellite imagery to coastal wetland dynamics and bird distribution. Ecological Modelling 258:1-12.
Title:Multiscale habitat selection of wetland birds in the northern Gulf Coast
Journal/Year:Estuaries and Coasts/2014
View:Visit Springer Link - Multiscale habitat selection of wetland birds in the northern Gulf Coast
Author(s):Bradley A. Pickens|Sammy L. King
Keywords:drawdown|marsh birds|marsh management|Rallidae|spatial scale|water depth
Abstract:The spatial scale of habitat selection has become a prominent concept in ecology, but has received less attention in coastal ecology. In coastal marshes, broad-scale marsh types are defined by vegetation composition over thousands of hectares, water-level management is applied over hundreds of hectares, and fine-scale habitat is depicted by tens of meters. Individually, these scales are known to affect wetland fauna, but studies have not examined all three spatial scales simultaneously. We investigated wetland bird habitat selection at the three scales and compared single- and multiscale models. From 2009 to 2011, we surveyed marsh birds (i.e Rallidae, bitterns, grebes), shorebirds, and wading birds in fresh and intermediate (oligohaline) coastal marsh in Louisiana and Texas, USA. Within each year, six repeated surveys of wintering, resident, and migratory breeding birds were conducted at >100 points (n=304). The results revealed fine-scale factors, primarily water depth, were consistently better predictors than marsh type or management. However, 10 of 11 species had improved models with the three scales combined. Birds with a linear association with water depth were, correspondingly, most abundant with deeper fresh marsh and permanently impounded water. Conversely, intermediate marsh had a greater abundance of shallow water species, such as king rail Rallus elegans, least bittern Ixobrychus exilis, and sora Porzana carolina. These birds had quadratic relationships with water depth or no relationship. Overall, coastal birds were influenced by multiple scales corresponding with hydrological characteristics. The effects suggest the timing of drawdowns and interannual variability in spring water levels can greatly affect wetland bird abundance.
Management Implications:Our study quantified an unprecedented diversity and abundance of marsh birds in the northern Gulf Coast marshes and underscores the importance of the region for resident and migratory birds. The region is also under threat due to high rates of wetland loss (Stedman and Dahl 2008). By studying a large wetland region, we were able to quantify wetland bird-habitat relationships, which are otherwise difficult to obtain when wetland area is a dominant limiting factor. The findings indicate coastal wetland birds respond to multiple spatiotemporal scales of hydrological characteristics, and the consistency of the relationships highlight the importance of water depth, and potentially hydroperiod, at the scale of marsh type, management, and fine-scale habitat. Marsh type and management are factors to consider in regional conservation planning, localized management, or selecting appropriate indicator species. We caution that the short-term benefits of permanent water impoundment may have negative long-term effects on vegetation, such as Typha expansion (Boers and Zedler 2008), whereas short-term benefits of spring drawdowns may lead to excessive oxidation of organic soils under some circumstances. Furthermore, the timing of drawdowns and interannual variability in spring water levels can greatly affect migratory and breeding wetland bird abundance. Drawdowns of water before migratory bird arrival will result in fewer wetland birds unless the marsh is reflooded after annual germination.
Citation:Pickens, B. A., and S. L. King. 2014. Multiscale habitat selection of wetland birds in the northern Gulf Coast. Estuaries and Coasts 37:1301-1311.
Title:Spatial and temporal patterns of range expansion of white-winged doves in the USA from 1979 to 2007
Journal/Year:Journal of Biogeography/2014
View:Visit Wiley Online Library - Spatial and temporal patterns of range expansion of white-winged doves in the USA from 1979 to 2007
Author(s):Jerrod A. Butcher|Bret A. Collier|Nova J. Silvy|Jay A. Roberson|Corey D. Mason|Markus J. Peterson
Keywords:Breeding Bird Survey|dispersal rate|introduced species|invasive species|North America|range expansion|spread|white-winged doves|Zenaida asiatica
Abstract:The geographical expansion of white-winged doves (Zenaida asiatica) in North America has attracted the attention of biologists and sportsmen because of their recreational and aesthetic value; however, data on factors driving the spatial spread of this species are lacking. We examined spatial and temporal patterns of range expansion for white-winged doves along the northern edge of their geographical range from 1979 to 2007 and used a dynamic occupancy model to estimate when and where doves would be found along an expansion gradient.
Management Implications:Estimating occurrence and range expansion of white-winged doves and other expanding/invasive avian species at large spatial scales can be effectively conducted using BBS data. Using these nationwide, long-term survey data to relate expansion to a suite of conditions likely to drive population dynamics is an effective approach to developing predictive models of range expansion.
Citation:Butcher, J. A., B. A. Collier, N. J. Silvy, J. A. Roberson, C. D. Mason, and M. J. Peterson. 2014. Spatial and temporal patterns of range expansion of white-winged doves in the USA from 1979 to 2007. Journal of Biogeography:in print.