The Siskiyou mule deer herd migrates from winter ranges primarily north and east of Mount Shasta (i.e., Day Bench, Lake Shastina, Montague, Mount Dome, Mount Hebron, Sheep-Mahogany Mountain, Tionesta, and Wild Horse Mountain) to sprawling summer ranges scattered between the Mount Shasta Wilderness in the west and the Burnt Lava Flow Geological Area in the east. A small percentage of the herd are residents, residing largely within winter ranges across the central and northeast areas of the herd’s annual distribution. The total population size of the Siskiyou herd is unknown, but adult deer densities averaged 6.01 deer per km2 on summer ranges in 2017 and 5.16 deer per km2 on winter ranges in 2019 (Wittmer and others, 2021). Some deer cross major highways during their seasonal migrations (U.S. Highways 97 and 89), and road mortalities of telemetered deer have been recorded. The summer range poses few concerns to the health of the herd, although limited water availability and recent forest fires may affect deer to some extent. Possible risks to deer population health on the winter range are relatively unknown. While recreational (hunting) opportunities have declined, the herd’s status is considered stable. These mapping layers show the location of the winter ranges for mule deer (Odocoileus hemionus) in the Siskiyou population in California. They were developed from 111 sequences collected from a sample size of 66 animals comprising GPS locations collected every 1-13 hours.