ABSTRACT
This chapter describes the Intermountain West Ecoregion where historically, the mule deer distribution was centered. The region is largely semiarid because of the rain shadow of the Sierra Nevada and Cascade Mountain ranges. Mule deer populations were low in this ecoregion prior to European colonization and introduction of agriculture and domestic livestock. Conversion of this largely grass-dominated region to shrubland allowed for large increases in populations of mule deer, culminating with high densities of mule deer in the 1940s. Populations have fluctuated widely over time. Invasion of exotic grasses with more frequent fire cycles altered habitats that once supported large numbers of mule deer, and those areas no longer support substantial populations. Habitat improvement projects restore mule deer habitat, provide sources of water, and reseed areas lost to fire. Major highways have made crossing structures essential to link fragmented habitats and migratory routes important to mule deer. Wildlife agencies predominantly use aerial survey to monitor deer populations in this open-canopied ecoregion. Population data combined with harvest data are used to prescribe seasons and permits to properly manage abundance in a transparent, public process.
