Graduate student Hailey Barton’s project involves collecting fecal samples from mule deer and desert bighorn sheep every month and measuring fecal nitrogen content, which indicates an animal’s nutritional status

Elephant Mountain Wildlife Management Area (EMWMA) sits at the heart of desert bighorn sheep restoration in Texas. Its acquisition in 1985 was intended primarily to replenish desert bighorn sheep populations and conserve other native species, such as mule deer. Desert bighorn sheep on EMWMA are incredibly reproductively successful. This steady increase in population has allowed managers with Texas Parks & Wildlife Department (TPWD) to translocate about 450 desert bighorn sheep from EMWMA to other areas in Texas in nine different translocation events since 1995.

While restoration has been successful thus far, there are lingering concerns about disease outbreaks and possible competition for resources with other species. With that in mind, managers are interested in protecting EMWMA for its crucial role in bolstering struggling herd numbers in different areas. Protecting the nursery herd of EMWMA involves protecting the resources it depends on. To obtain the best outcome for desert bighorn sheep, other native species (i.e., mule deer), and the landscape, TPWD and Borderlands Research Institute (BRI) researchers have teamed up to determine the carrying capacity of desert bighorn sheep on EMWMA. While we already have a current estimate of how many desert bighorn sheep we think EMWMA can support, we know carrying capacity changes yearly with variable weather patterns and the available vegetation. Estimating carrying capacity involves a lot of work that is time-consuming and too cost-prohibitive to conduct annually. To circumvent this, we use satellite imagery to monitor available vegetation, allowing us to estimate carrying capacity quickly, more precisely, and more often.

Graduate student Hailey Barton’s project involves collecting fecal samples from mule deer and desert bighorn sheep every month and measuring fecal nitrogen content, which indicates an animal’s nutritional status. She will compare desert bighorn sheep and deer fecal nitrogen content each month with the average monthly Modified Soil Adjusted Vegetative Index (MSAVI) value of the vegetation taken from satellite imagery which indicates the “greenness” of the vegetation on the landscape. These data are collected before and after a translocation of desert bighorn sheep from EMWMA to observe how the nutritional status of deer and desert bighorn sheep changes with differing numbers of desert bighorn sheep on the mountain. In addition to this relationship, Hailey has also conducted vegetation surveys. She will compare that data with satellite imagery to determine what habitat factors can be reliably captured via satellite, and which must be measured on the ground. Ultimately, these efforts will help managers by providing critical information to guide decision making and maximize the benefit of on the ground sampling.

Hailey’s project will build the framework to show what the fecal nitrogen-MSAVI relationship looks like immediately before and after a translocation event. BRI researchers will continue this work to see how that relationship unfolds in the years between this translocation and the next. The final product of this project will allow us to gauge the nutritional performance of desert bighorn sheep and mule deer at a given value of MSAVI that is provided by satellite imagery. The goal is to provide TPWD with this knowledge so that they may more easily determine how many desert bighorn sheep they would like to keep on the mountain, which will help them decide how often they can conduct translocations, and how many desert bighorn sheep they should move when they do.