Contract Research Findings: Amphibians


Title: Short-term response of herpetofauna to various burning regimes in the South Texas plains
Journal/Year: The Southwestern Naturalist/2008
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Author(s): Donald C. Ruthven, III | Richard T. Kazmaier | Michael W. Janis
Abstract: Data on effects of fire on herpetofauna generally are lacking. With increased use of prescribed fire to manage rangelands in South Texas for wildlife and livestock, a better understanding of effects of fire on the herpetofauna is needed. We investigated effects of combinations of winter and summer prescribed fire on rangeland sites on the Chaparral Wildlife Management Area in southern Texas. Dormant-season fires had little effect on diversity and abundance of the herpetofauna. Inclusion of growing-season fire into the burning regime tended to increase diversity and abundance of grassland species, such as the six-lined racerunner (Cnemidophorus sexlineatus). Although our experimental design limits interpretation of results to the study site, our data suggest that prescribed fire may be used to manage rangelands in South Texas without negative effects on the herpetofauna. A varied burning regime is recommended to increase herpetofaunal diversity.
Management Implications: In the short-term, burning rangelands in South Texas during winter appears to have little effect on the herpetofauna, whereas fire in summer provided slight increases in diversity and an increase in abundance of grassland species. Our data suggested that land managers can use fire as a management tool without deleterious effects on herpetofaunal communities. We concur with the findings of Braithwaite (1987), that a mosaic of burning regimes may promote overall faunal diversity. Research investigating effects of land-use practices, such as prescribed fire, on herpetofauna lag behind other vertebrates (Friend, 1993; Russell et al., 1999; Pilliod et al., 2003). To fully understand impacts of prescribed fire on the herpetofauna of rangelands in South Texas, long-term research and monitoring of a wide variety of burning regimes with broader sampling methods to increase sample sizes and species encountered is warranted.
Citation:Ruthven, D. C., III, R. T. Kazmaier, and M. W. Janis. 2008. Short-term response of herpetofauna to various burning regimes in the South Texas plains. The Southwestern Naturalist 53:480-487.

Title:A safe and efficient technique for handling Siren spp. and Amphiuma spp. in the field
Journal/Year:Herpetological Review/2009
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Author(s):Donald J. Brown | Michael R. J. Forstner
Management Implications:We found that a single person could restrain and obtain all necessary data on a given individual in under ten minutes. A potential drawback of this method is that the salamanders will never be perfectly linear due to the necessity of having enough space to facilitate movement into the tube. However, once an individual is placed in a given tube, a smaller tube can be inserted at the anterior end and the salamander can be coerced into it by touching its tail, resulting in a tighter fit and more accurate measurements. The handling method we used was effective for collecting standard data and facilitating tail-clips. This method may not be useful when extremely accurate measurements are required or when investigating some morphological characters, such as bite-marks (Fontenot and Seigel 2008; Godley 1983). However, the tubes may be useful for restraining individuals prior to administering anesthetic vapor.
Citation:Brown, D. J., and M. R. J. Forstner. 2009. A safe and efficient technique for handling Siren spp. and Amphiuma spp. in the field. Herpetological Review 40:169-170.

Title:Effects of summer and winter burning on vegetation and wildlife in a sand sagebrush/honey mesquite savanna
Journal/Year:Thesis/2009
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Author(s):Matthew W. Poole
Abstract:There is substantial information on the generalized effects of fire in some grassland ecosystems. However, studies addressing seasonality of fire are less common. The Rolling Plains have high climatic variability with periodic droughts; however, little information is available on the potential role of burning in these communities under these conditions. Therefore, I initiated a project to explore the effects of seasonality of fire on a sand prairie ecosystem. We established 5 blocks of 3 18-ha plots at Matador Wildlife Management Area (WMA) in Cottle County, Texas. Each plot, within a block, was randomly assigned to a summer burn (August), winter burn (February), or a control (no fire) treatment. Herbaceous vegetation cover and frequency were measured twice annually (May-June and August-September) using 0.1 m² quadrats, while woody cover was measured during late summer using the line-intercept method. Invertebrates, herpetofauna, and small mammals were sampled utilizing drift fence arrays during the spring and summer. Invertebrates were also sampled in late summer using sweep nets and small mammals were also sampled twice annually using Sherman live traps. Summer burning appeared to benefit forbs, species richness, evenness and diversity. In general, forbs were not affected by winter burning, but forbs were similar to grasses, in that individual species' responses to winter burning were variable. My results indicated that prescribed summer burning appears to be effective at reducing, but not eliminating sand sagebrush, honey mesquite, prickly pear, yucca, and total woody canopy cover. Summer burning was the most effective treatment at reducing honey mesquite and sand sagebrush, which may have promoted the observed increases in herbaceous vegetation by making resources, such as light and water, available to grasses and forbs. However, many of the wildlife species examined did not respond to the application of summer and winter burning, but responded to onset of drought conditions. Therefore, a combination of both summer and winter burning treatments are recommended for suppressing woody plant cover and increasing overall plant diversity by promoting desirable herbaceous species for a wide variety of wildlife and livestock. Longer term research on the effects of summer and winter burning on herbaceous and woody vegetation, especially in drought years, is needed to fully evaluate the effects of burning in the Rolling Plains of Texas.
Citation:Poole, M. W. 2009. Effects of summer and winter burning on vegetation and wildlife in a sand sagebrush/honey mesquite savanna. Thesis, West Texas A&M University, Canyon, USA.

Title:Impact of reduced flooding on herpetofauna in a TPWD bottomland
Journal/Year:TPWD Final Report/2009
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Author(s):Neil B. Ford | Shaun Crook | Stephen Lange
Abstract:Floodplain forests are among the most threatened habitats in North America. We used the species richness, ranked abundance, and diversity of amphibians and reptiles to assess the effects of flood suppression at the Old Sabine Bottom Wildlife Management Area (OSBWMA) in Smith County, Texas, USA. Amphibians and reptiles were surveyed using visual surveys, cover boards, and with minnow traps at ephemeral pools: in undisturbed bottomland forest, in maintained openings, and a bottomland hardwood regeneration site (Baker Tract). We observed a total of 3343 amphibians and reptiles representing 45 species in 2007 through 2009 (sample period two) whereas 2280 records of 42 species were made in 1998 and 1999 (sample period one). Species diversity indices and rarefaction adjusted richness were not different between years of sample period one (1998-1999) and years of sample period two (2007-2009) but community comparison indices indicated that changes occurred for some species. The ranked abundance of each species was compared to their ranking in the datasets of each sample period. The number of southern leopard frogs increased and the number of small-mouthed salamanders decreased during sample period one. Turtles and lizards did not vary much between sampling periods. Terrestrial snake species such as king snakes and earth snakes became more abundant in the later period. We used GIS to assess how collections of amphibians and reptiles differed in a year with reduced (less winter) flooding to one with a more normal (winter) flood pattern. Overall, the presence of amphibians varied according to the flooding patterns and these animals were restricted to more permanent water if the floods were reduced. The change in the herpetofaunal communities suggests that changes in flooding have a measurable effect on the surveyed makeup of amphibians and reptiles in this floodplain. One caveat, however, is that during the same period, hog activity increased dramatically and may have had impacts on the same fauna in ways that cannot be interpreted with this data.
Management Implications:An increase in the impact of feral hogs on the OSBWMA was evident from the first study in 1998 and 1999 to the current research. Some of this may just be the result of an increased population of feral hogs on the WMA. In addition, hunters have increased success during flooding, as the hogs are restricted to higher ground during that time. However, it also appeared that during reduced flooding years, hogs were concentrating foraging around ephemeral pools and the edges of creeks and streams due to dryer conditions. This may be a result of the reduced flooding in that the interior sites were dryer than in the years with flooding. Turning the vegetation around pools where the ground is softer appeared to be a foraging strategy that hogs were employing in this area. Therefore the impact of the hogs on amphibians and other animals living near ephemeral pools was acerbated by the reduction in flood regimes. Wood duck predation in bottomland hardwood is reduced during floods. Predators such as Texas rat snakes appear to have difficulty locating nests when a floodplain is inundated by water (Carfagno and Weatherhead, 2009, Roy Neilsen and Gates, 2007). Since duck reproduction is often in the spring when the flooding is normally occurring, a reduction in flooding periodicity or duration could have an impact on the ability of wood duck populations to recruit young of the year. Monitoring wood duck boxes in years with normal flood patterns and those of reduced frequency would be an important project for this WMA. It is also likely that predation on other cavity nesting species, like Eastern Grey Squirrels, might be impacted by reduced flooding and should be monitored also.
Citation:Ford, N. B., S. Crook, and S. Lange. 2009. Impact of reduced flooding on herpetofauna in a TPWD bottomland. Texas Parks and Wildlife Department Final Report, Austin, USA.

Title:Trade in non-native amphibians and reptiles in Texas: lessons for better monitoring and implications for species introduction
Journal/Year:Herpetological Conservation and Biology/2011
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Author(s):Heather L. Prestridge | Lee A. Fitzgerald | Toby J. Hibbitts
Keywords:exotic species | invasive species | LEMIS database | wildlife trade
Abstract:In the United States, trade is monitored at different levels of government, and state level insight requires combining federal, state, and local sources of information. Trade in wildlife and their products has implications on wild populations of species involved, and introduction of non-native vertebrates, especially amphibians and reptiles, is linked to the commercial trade in these animals. We used: (1) federal databases; (2) surveys of pet owners at live animal expositions; (3) observations of sales at live animal expositions; and (4) data collected from dealers on the Internet to quantify imports, exports, and use of exotic herptiles traded in Texas. We recorded 1,192 unique taxonomic entities of amphibians and reptiles in commercial trade in Texas. A total of 949,901 live specimens were imported to Texas from 2002 to 2008. The top 16 imported taxa made up 73.36% of the trade. Internet and exposition-based trade was dominated by few species of common pets, with others represented in small numbers. Much trade persists in known invasive species and others that must have the potential to become invasive. We documented trade in 36 known invasive species, three of which are invasive in Texas. Our approach could serve as a template for assessing trade in non-native species at regional scales. Modifications to national databases would allow exports to be distinguished from re-exports, and adoption of standardized taxonomy would improve understanding of impacts of trade on species. State level management changes should be consistent across all 50 states to add continuity to laws governing non-native amphibians and reptiles kept as pets.
Management Implications:Shortcomings of the USFWS reporting system have previously been pointed out and include allowance of multiple codes for the same taxonomic entity, partial codes, and generalized codes. Schlaepfer et al. (2005) noted that non-identified shipments could include imperiled species or non-natives known to be invasive. Ceballos and Fitzgerald (2004) recommended that precise information on origin of specimens is needed to understand impact of the trade on wild populations as well as to achieve accurate monitoring. We avoided some of these problems by cross-referencing our database queries and developing criteria for estimating the total number of taxa. However, partial codes, generalized codes, and poor nomenclature posed problems that impeded our ability to precisely identify the number of species and subspecies in the trade. We recommend that vague entries in trade databases such as "Non-CITES Reptile or Amphibian", "Reptile", or "Amphibian" not be permissible for commercial shipments. Utilization of the Taxonomic Serial Number (TSN) provided by the Integrated Taxonomic Information System, would be a positive step towards clarifying identities of species in the trade, but recommendations to adopt the TSN have yet to be implemented (Gerson et al. 2008). Benefits of standardized nomenclature for traded species would enable more complete analysis of trade data and enhance the ability of inspectors to identify species in shipments. Standard nomenclature is also needed to develop enforceable criteria for the level of taxonomic identification required for different types of shipments. Gerson et al. (2008) claimed that through the adoption of the TSN system, traders would be forced to become more knowledgeable and forthcoming about the taxonomic status of species traded. It is unrealistic to expect commercial traders to keep up with changes in current scientific nomenclature. Government agencies and NGOs should work together to develop standard names or TSN codes that commercial traders are required to use for reporting. This requirement would improve trade monitoring systems and reduce confusion caused by reporting old and new names for the same species. The problem of importing regulated species under false names would still exist as well as incorrect identifications. Nevertheless, trade monitoring systems would be greatly improved if the TSN coding system were adopted or standardized genus and species names were required for commercial trade shipments. Our results indicated the growing role of Internet-based sales of live animals in the pet trade. It is increasingly important to monitor Internet trade, as the use of e-commerce has created a global market for wildlife and their products. The pet trade is very risky for species invasion problems because the number and suite of species used as pets changes over time and the magnitude of the pet trade overall is growing. In contrast, the number of species used for food and skins is relatively stable. Kraus (2009) draws interesting correlations between the pathway of introduction of an invasive species with geographic region of the introduction noting pet trade is the most common pathway for live, non-native reptiles and amphibians to be introduced to North America. When considering these factors combined with our results showing that Internet and exposition trade in live, non-native species is flourishing in Texas, it is clear that management should focus on specimens that are traded live for pets. Our study is among the first to use multiple data sources at the national level, state level, data on Internet-based trade, and targeted interviews to reveal detailed patterns of trade among a large number of genera, species, and subspecies of amphibians and reptiles. Our approach could be used as a template for assessing trade in non-native species in other states, especially those with a high volume of documented dealers, breeders, or enthusiasts. We showed that much trade persists in known invasive species and others that must have the potential to become invasive. Continued monitoring of species involved in trade and quantities imported is critical in developing management strategies for all species traded live but also conservation practices for those traded as products.
Citation:Prestridge, H. L., L. A. Fitzgerald, and T. J. Hibbitts. 2011. Trade in non-native amphibians and reptiles in Texas: lessons for better monitoring and implications for species introduction. Herpetological Conservation and Biology 6:324-339.

Title:Plant and small vertebrate composition and diversity 36-39 years after root plowing
Journal/Year:Rangeland Ecology and Management/2013
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Author(s):Timothy E. Fulbright | E. Alejandro Lozano-Cavazos | Donald C. Ruthven, III | Andrea R. Litt
Keywords:amphibians | brush management | Prosopis glandulosa | reptiles | rodents | woody plants
Abstract:Root plowing is a common management practice to reduce woody vegetation and increase herbaceous forage for livestock on rangelands. Our objective was to test the hypotheses that four decades after sites are root plowed they have 1) lower plant species diversity, less heterogeneity, greater percent canopy cover of exotic grasses; and 2) lower abundance and diversity of amphibians, reptiles, and small mammals, compared to sites that were not disturbed by root plowing. Pairs of 4-ha sites were selected for sampling: in each pair of sites, one was root plowed in 1965 and another was not disturbed by root plowing (untreated). We estimated canopy cover of woody and herbaceous vegetation during summer 2003 and canopy cover of herbaceous vegetation during spring 2004. We trapped small mammals and herpetofauna in pitfall traps during late spring and summer 2001-2004. Species diversity and richness of woody plants were less on root-plowed than on untreated sites; however, herbaceous plant and animal species did not differ greatly between treatments. Evenness of woody vegetation was less on root-plowed sites, in part because woody legumes were more abundant. Abundance of small mammals and herpetofauna varied with annual rainfall more than it varied with root plowing. Although structural differences existed between vegetation communities, secondary succession of vegetation reestablishing after root plowing appears to be leading to convergence in plant and small animal species composition with untreated sites.
Management Implications:A concern regarding use of root plowing to manage woody plants is that it can cause permanent changes in vegetation structure and composition that are undesirable for wildlife. Based on our long-term (>three decades) data, root plowing should be avoided if land managers wish to maintain woody plant species richness and diversity. Effects of root plowing, however, do not appear to be a conservation concern for small vertebrate communities on the Chaparral Wildlife Management Area in Texas.
Citation:Fulbright, T. E., E. A. Lozano-Cavazos, D. C. Ruthven, III, and A. R. Litt. 2013. Plant and small vertebrate composition and diversity 36-39 years after root plowing. Rangeland Ecology and Management 66:19-25.