California Mule Deer Pacific Migration Stopovers

The Pacific mule deer herd inhabits 353 square miles (mi2; 914 square kilometers [km2]) of public and private lands in Placer and El Dorado counties in California, including the Eldorado National Forest as well as private lands owned by Sierra Pacific Industry and Sacramento Municipal Utility District. During fall migration, Pacific mule deer move approximately 19 mi (30 km) to the foothills of the western Sierra Nevada Mountains, using stopovers in route to their summer range (figure XXX). U.S. Highway 50 and the Middle Fork American River bound the herd’s migration routes on the south and north, respectively. During winter, the migratory portion of the population intersperses with resident deer at lower elevations (2,296–2,953 ft [700–900 m]). The Pacific mule deer herd has been declining for decades because of several factors, including predation, recreation, poaching, disease, and fire suppression. Recent studies indicate a below-average adult survival rate of 77 percent for this herd (Merrell and others, 2023). In 2014, the King fire, a severe wildfire, burned 151 mi2 (390 km²) across much of the mid-elevational area between September and October. Plant succession following the fire modified the way mule deer use the area; does now remain in these recently-burned areas during winter months (Merrell and others, 2023). These mapping layers show the location of the migration stopovers for mule deer (Odocoileus hemionus) in the Pacific population in California. They were developed from 149 migration sequences collected from a sample size of 43 animals comprising GPS locations collected every 1-13 hours.