Seasonality in Sonoran pronghorn survival and movement within a managed rangeland

The endangered Sonoran pronghorn (Antilocapra americana sonoriensis) has a large portion of its range within a military operations area in southwestern Arizona, USA. Sonoran pronghorn have been actively managed in this region for more than 20 years. Recovery efforts have included release of captive-born pronghorn into areas both currently and historically occupied by wild pronghorn. These areas provide habitat for federally endangered essential and experimental non-essential, referred to as 10(j), pronghorn populations. More than 20 years of monitoring efforts have resulted in a large dataset on their spatial occurrence and movement within these areas. To synthesize long-term trends and seasonality in Sonoran pronghorn movement and mortality, we employed a suite of quantitative analyses that characterized the pronghorns' 1) individual and population-level home ranges, 2) occurrence near active military targets, 3) trends in seasonal group sizes and composition, 4) sex- and group-specific survivorship, and 5) changes in movement-based behavior following release from captivity. We found strong seasonal trends throughout, including sex-specific differences in seasonal movement rates, home ranges, survival, and group composition. Further, captive-born pronghorn released into the endangered population exhibited markedly higher survival compared to those released in 10(j) areas. Captive-born pronghorn exhibited significant seasonal use of active military target areas. These analyses, which represent the most comprehensive analysis of Sonoran pronghorn movement and survival to date, have important implications for the future conservation and management of this endangered species. Our results indicate that active management of endangered Sonoran pronghorn has successfully increased survival, and we recommend maintaining or increasing current recovery efforts, such as captive breeding and placement of supplemental resources throughout their range (e.g., freestanding water and supplemental forage), to further boost the survivorship of both wild- and captive-born pronghorn. Moreover, future management efforts could use our seasonality results to create dynamic prediction models of when and where pronghorn are likely to overlap with military activities to best manage interactions. Our methods have added application to other mobile species of conservation interest occurring in disturbed and resource-limited landscapes.