FEMALE MULE DEER RESPONSE TO FORAGE AVAILABILITY AND PREDATION RISK IN A MOJAVE DESERT SKY-ISLAND LANDSCAPE

Christopher E Lowrey; USGS; clowrey@usgs.gov; Kathleen M. Longshore, David Choate, Daniel Thompson, Jyothy Nagol, Joseph Sexton

Forage availability and predation risk interact to affect habitat use of ungulates across many biomes. Within the isolated sky-island habitats of the Mojave Desert, increased availability of diverse resources may provide ungulates in this desert ecosystem with unique opportunities to extend forage availability or mitigate predation risk. We addressed whether habitat use and foraging strategy of female mule deer (Odocoilus hemionus) responded to Normalized Differential Vegetation Index (NDVI), NDVI rate of change (NDVIR or green-up), or the occurrence of cougars (Felis concolor) in the Desert National Wildlife Refuge of southern Nevada. Female mule deer used available green-up primarily in spring, although greening vegetation was also available during other seasons. Mule deer and cougar shared similar habitat all year, and cougars had a consistent, negative effect on mule deer access to greening vegetation. A seemingly late parturition date combined with diminishing forage quality during the lactation period. Our findings suggest female mule deer were unwilling to increase perceived predation risk from cougars to access the greater resources of Mojave Desert sky-islands.

Ecology and Conservation of Mammals III