Modeling Pronghorn Behavior and Movement Using Range Size Across Time: Translocated vs. Resident

Erin O’Connell, Justin French, Carlos E. Gonzalez, Louis A. Harveson, and Shawn Gray (TPWD)

Megafauna extinctions are a global issue, and translocation is one of the most widely used tools for restoration. Starting in 1939, Texas Parks and Wildlife Department (TPWD) translocated over 6,200 pronghorn (Antilocapra americana). Despite early indications of population growth, there are still restoration challenges. While translocations are a tool to reintroduce species, they tend to be stressful to the animals and are economically and logistically challenging.

To alleviate challenges, it is important to conduct long-term studies to investigate challenges, such as habitat fragmentation, restrictive movement due to fencing, and space-use. Understanding pronghorn space-use is critical for translocation success efforts, and translocation projects should consider the complex dispersal and habitat selection processes.

In January 2019, we partnered with TPWD to affix Global Positioning System (GPS) collars on 44 translocated pronghorn from Pampa, Texas, to Rocker b Ranch. In January of 2020, BRI and TPWD collared 20 resident pronghorn on Rocker b Ranch to study resident behavior. The purpose of this project is to explore resident and translocated pronghorn behavioral plasticity and other labile traits to meet long-term restoration goals, such as population stability.

We will use a Kernel Density Estimator to estimate the Utilization Distribution to understand pronghorn space-use and post-translocation behavior. This will allow us to estimate the average resident range size, the initial difference in translocated range size, and the final difference in the translocated range size.

Preliminary results suggest that residents maintain a relatively static range size post-translocation, while translocated pronghorn maintain larger range sizes following translocation. At two and a half months post-translocation, translocated individuals acclimate to their new habitat and maintain smaller range sizes. This time period is a mark that TPWD can use to assess pronghorn translocation success. These results provide information for TPWD biologists, as well as provide landowners and ranch managers with guidelines for space-use of pronghorn in West Texas rangelands.

Funding sources: The Meadows Foundation, Respect Big Bend coalition.