The Sumpter mule deer herd includes resident and migratory individuals. Mule deer wintering near Oregon Route 244 and La Grande, Oregon, migrate south to Wolf Creek, Glass Hill, and Elkhorn Ridge in spring. Although mixed-conifer forest and ponderosa pine dominate seasonal ranges for these mule deer, winter ranges contain more sagebrush grassland and summer ranges contain more riparian and early shrub-tree habitats. Other mule deer wintering in patches of big sagebrush mixed with conifer, ponderosa pine, western juniper, and quaking aspen forests near North Powder Valley and Powder River also migrate to Elkhorn Ridge for the summer. Some mule deer along Burnt River, where winter ranges are characterized by big sagebrush, western juniper, and grassland, migrate south to areas with more mixed-conifer forest and invasive annual grasses near Monument Rock and Willow Creek in spring. Other mule deer either migrate north or west to Austin, Oregon, and Oregon Route 7, where big sagebrush, mountain big sagebrush, mixed-conifer forest, and ponderosa pine are common. Some of these mule deer travel as far north as Elkhorn Ridge and Wolf Creek. In 2015, the Cornet-Windy fire burned 56,766 acres (22,972 ha) of forested summer range near Oregon Route 245 (BLM, 2023a), improving browse quality but potentially reducing shelter by decreasing canopy cover. Highways are a significant cause of mortality in this area; for example, Interstate 84 had an annual average of 162 DVCs from 2010 to 2022 along a 100-mile (161-km) section (ODOT, 2023). No GPS-collared mule deer successfully crossed Interstate 84 although multiple seasonal ranges and migrations closely bound the highway, indicating a possible loss of historical migration routes. These mapping layers show the location of the winter ranges for mule deer (Odocoileus hemionus) in the Sumpter population in Oregon. They were developed from 198 winter sequences collected from a sample size of 88 animals comprising GPS locations collected every 5-13 hours.