Season and Migration Strategies Influence Mule Deer Response to Landscape Mosaic

Landscape-scale ecosystem degradation in the western United States has been attributed to altered fire regimes, tree expansion into shrublands, and the invasion of exotic annual grasses. These changes have impacted populations of many wildlife species, including mule deer (Odocoileus hemionus). We examined how wildfire, dominant vegetation type, western juniper (Juniperus occidentalis) cover, vegetation productivity, and elevation influenced seasonal habitat selection for a population of mule deer that exhibits mixed-migration strategies. We used 51 416 global positioning system locations collected from adult (>1.5-yr-old) female mule deer to develop three separate population-level resource selection functions for the shared winter range (n = 148; December–March) and migratory summer range (n = 94; June–August), and resident summer range (n = 34). We found that both migratory and resident deer used older burns (11–20 yr) on summer ranges. Conversely, deer used more recent burns (<10 yr) more than unburned areas during winter. During the winter, deer also used areas with little juniper cover (<10%) and patches dominated by exotic grass. Our results indicate that wildfire has both positive and negative effects on mule deer habitat selection, depending on the season and age of burn. Furthermore, our results identify a threshold of juniper canopy cover selected by mule deer on their winter range.