Spatial distributions and resource selection by mule deer in an arid environment: Responses to provision of water

In arid ecosystems free-standing water is a critical resource for both humans and wildlife. Understanding use of limiting resources by large mammals presents unusual challenges since body size is related to physiological needs and broad spatial distributions. We investigated effects of provision of water on patterns of space use and selection of resources by mule deer (Odocoileus hemionus), a medium-bodied ungulate with wide distribution across North America. We created 3 study areas with varying availability of permanent water. We hypothesized that daily movements and utilization distributions (UDs) would be smaller in areas with greater availability of water, and that we would observe strong selection for sources of water relative to other resources. We used resource selection functions to evaluate the importance of permanent water in selection of resources. Daily movements and areas of UDs were smallest in the water-provided area, especially during summer. Mule deer selected areas closer to water during all seasons relative to other available resources. Predicted changes in climate and increased likelihood of droughts will undoubtedly result in shifts in resource availability and selection of resources, which likely will make provision of water a key factor in maintaining viable populations of large mammals in arid ecosystems.