Kerr WMA: Management Program


Phone: (830) 238-4483
Address:
2625 FM 1340
Hunt, TX 78024

Contact: Ryan Reitz

Dates Open:

Open year round, except closed for Special Permit hunts. The office is open Monday through Friday, 8:00 am to 5:00 pm.

Kerr WMA Driving Tour & Birding Map:

Events

Seminars and tours are annually hosted on the Kerr Wildlife Management Area (WMA).

Seminars include information on historical accounts of the Texas Hill Country and the Kerr WMA along with ecosystems management information using a holistic approach to land improvement. They also cover a summary of past and present deer research, over 40 years, from the Donnie E. Harmel White-tailed Deer Research Pens; an update on the status of feral hogs; a look at different management techniques for deer and general wildlife and an overview of TPWD programs that are available to assist landowners. We also offer a field tour of the WMA and the research facilities.

Please contact the Kerr WMA headquarters by calling (830) 238-4483 for more information and registration.

Management Program

When the Kerr WMA was purchased in 1950, the entire area was in poor range health due to a long history of mismanagement. The predominant overstory vegetation was mature Ashe juniper, commonly referred to as cedar. These dense, mature stands prevented sunlight and moisture from reaching the lower growth of vegetation, namely grasses and forbs, and suppressed their growth. The range had been overgrazed by livestock and the deer population at that time was well over carrying capacity which led to relatively small, unhealthy deer. A few golden-cheeked warblers may have existed on the WMA, and presence of black-capped vireos was highly unlikely.

Historically, this area was largely a mid-to-tall grassland savannah with brush and oaks confined to steep canyons and riparian zones. Large numbers of bison frequented the area along with pronghorn antelope, black bear, wolves, white-tailed deer, and wild turkeys. Fire and bison played integral roles in maintaining the grassland and prevented brush species from becoming established. That was a time when deer were few, but overall wildlife diversity was rich.

Today, the Kerr WMA is supporting some of the healthiest plant and animal communities in the Hill Country as a result of the planned application of a variety of management practices. This includes brush control, rotational grazing, prescribed burning, deer harvest (whitetails and exotics), and cowbird trapping. Since the 1950s, wildlife diversity is greater, deer and calf weights have increased, fawn survival is higher, antler development has improved, and populations of endangered species (golden-cheeked warblers, black-capped vireos and Tobusch fishhook cactus) have flourished.

Management success is evident through the data collected over the last several decades:

Leopold's Tools of Wildlife Management

Aldo Leopold, considered the father of wildlife ecology, wrote a book in 1933 titled Game Management in which he defined the five tools of game and habitat management: axe, cow, plow, fire and gun. The Kerr WMA has intensively applied these tools in its efforts to improve wildlife habitat and maintain a healthy ecosystem.

Axe icon Based on research at the Kerr WMA, large acreages of mature Ashe juniper were removed from 1964 through 1966 by hand cutting for posts and by chaining. Today we still apply brush control methods, but primarily utilize mechanical treatments, such as hydraulic shears, which greatly reduces soil disturbance and erosion. Approximately 1/3 of the area remains in mature juniper. Some juniper stands were left in rough draws, adobe hills, and other sites with a low potential for production to serve primarily as cover for wildlife. One large, 530-acre parcel was left to act as a relic site and also provide nesting habitat for the golden-cheeked warbler which was not listed as endangered until 1990.

Cow icon The Kerr WMA views livestock as a tool to manipulate and manage for improvement in wildlife habitat and plant diversity. The main role of grazing on the WMA is to reduce the grass quantity, allowing sunlight to reach the lower growing forb species, which are extremely important for wildlife. After evaluating several grazing systems, we found that a short duration system produced the desired results. We use one herd of cows that are rotated through 27 pastures. Each pasture is intensively grazed for 2 to 10 days before the cattle are moved to the next pasture. Movement of livestock in individual pastures is based on pasture size, growing conditions, soil site and livestock performance. This system allows for a short, intense grazing period followed by a long (90 day) rest period before cattle return to that pasture. This grazing system closely mimics the historic grazing of the bison herds.

Fire icon By 1979, it was becoming evident to Kerr WMA biologists that neither money nor manpower were going to be able to control the reinfestation of regrowth juniper, so they began experimenting with prescribed fires. Research on these early burns showed that juniper with less than one inch basal diameter could be easily killed without much harm to the vegetative overstory of canopy trees. It was effective in removing plants that did not resprout from the base, like juniper, without killing the rest of the vegetation.

Cattle are often grazed immediately in burned pastures for a short period to utilize unburned patches of grass and prickly pear cactus. In one study, cattle grazing immediately following prescribed fire had resulted in 65% of the prickly pear being consumed. After a short grazing period following the burn, the pasture is rested for 90 days to allow the burned site to recover.

The Hill Country rangelands have developed and evolved under a natural fire regime, and the practice of prescribed burning continues to shape and improve the wildlife habitat by reducing regrowth cedar, promoting regeneration of desirable browse species, and increased the palatability of many forage species. Each year about 10 to 15% of the WMA (500 to 1,000 acres) is set aside for late winter burns. The burn program has increased the production of grass, browse, and perennial forbs. Preferred deer browse, such as redbud and flameleaf sumac, will actually increase after a fire. White-tailed deer, which are not normally grass eaters, will also consume large quantities of grass in burned areas because it is in a young, nutritious, and more digestible state. Prescribed burning has also been instrumental in providing the required nesting habitat for the black-capped vireo.

Gun icon The harvest of surplus deer began in 1954 with a controlled buck-only hunt. Biologists realized the need to harvest deer of both sexes in order to reduce populations to levels at or slightly below carrying capacity. Either sex hunts have been conducted since 1958. Earlier studies conducted on the Kerr showed that a deer density of one deer per 10 acres could be maintained without a major die-off and without degrading the habitat.

Early management practices resulted in greatly improved range conditions, which in turn attracted deer to the area despite increased hunting pressure. Although removing large numbers of deer resulted in short-term range improvement, the constant ingress of deer onto the WMA made achieving population goals impractical.

In the summer of 1968, a 7 ½ foot deer-proof fence was constructed around the WMA to stop the ingress of deer and allow biologists the ability to attain carrying capacity goals. Population goals were reached in 1972 and the deer population continues to be managed at the carrying capacity of the WMA.

Preservation versus Conservation

In 1954, Kerr WMA biologists decided to make one of the 96-acre research plots into a site where no management practices would be applied. They wanted to demonstrate an area that basically allowed Mother Nature to take over. This site, referred to as "Plot 9", was considered one of the best range sites on the Kerr WMA at that time. It was predominantly a live oak savannah with a good diversity of vegetation. All deer were removed, and it has not been grazed, burned or mechanically treated for the past 65+ years.

Initially there was a positive response in the variety of grasses and forbs found in plot 9. Vegetation transects in the early 1960s showed an all-time high of 47 different species, but that number gradually decreased over time. By 1989, we observed an all-time low of only 14 species, with only one forb species, and also a significant increase in the amount of bare ground. Conversely, we observed a tremendous increase in juniper. Today the entire plot is dominated by a juniper woodland.

This is an example that some would define as an act of preservation, where any human disturbances are removed from the landscape. The hope is that the plant community will persist in its current state in perpetuity. However, plant communities are not static and are always evolving towards another state based on their environmental influences, or lack thereof. This is a natural process called plant succession. The early successional stages are characterized by forbs and grasses, and the later, ultimate stage is a dense woodland. Since not all wildlife species utilize the same type of habitat, diversity and health of animal populations are strongly associated with landscapes that provide a variety of successional stages. Conservation is the practice of managing for a desired stage, or stages, of plant succession. Historically, major disturbances, such as wildfire and bison grazing, kept the landscape in various stages of plant succession. Today those natural influences rarely occur. Therefore, land managers must actively apply disturbances, through available management tools, in order to maintain or setback plant successional stages to create a more diverse ecosystem.

Plot 9, 1959

Plot 9, 1959

Plot 9, 2006

Plot 9, 2006