Limited resources shape home range patterns of an insular ungulate in a semi-arid ecosystem

Abstract

Understanding patterns of home range size and selection are critical to protect vulnerable wild populations, particularly in semi-arid regions with increasing land use pressures. Using movement data from 64 GPS-collared southern mule deer (Odocoileus hemionus fulinginatus), monitored over two years in San Diego County, we assessed patterns and drivers of home range following a two-step approach. First, we implemented seasonal home range selection functions to examine variation in selection and avoidance of environmental factors. We then used these results to evaluate the relative impact of environmental factors in combination with intrinsic factors on home range size. We found that deer use of high-quality forage and water sources varied seasonally. These variations in resource use, along with sex and age, played a role in determining home range size of the southern mule deer. Home range size was larger for male deer, and smaller among older females. Home ranges for both sexes were smaller when forage quality increased and larger with greater variability in water proximity. The limited resources of semi-arid environments, like water and forage, affect southern mule deer populations and highlight the importance of evaluating combined intrinsic and extrinsic factors of home range size and composition to inform management practices.