Below is a news release from the Idaho Department of Fish and Game.
As days get shorter and temperatures start to fall, mule deer and elk make their way from the Boise Mountains to the Boise foothills seeking lower elevations, mild temperatures, and available forage to survive the winter. Some come from as far away as the Sawtooth Mountains.
The Boise River Wildlife Management Area (WMA) is the primary winter range for Unit 39 mule deer and elk. An estimated 5,000 to 8,000 mule deer and 1,800 elk winter on the WMA each year.
Situated in the foothills of the Boise Mountains along Lucky Peak and Arrowrock Reservoirs, the WMA spans 36,000 acres and supports more than 300 species of wildlife.
There are plenty of wildlife viewing opportunities year-round on the WMA. During the winter months, visitors can observe mule deer, elk, and pronghorn along State Highway 21, it is important that drivers slow down this time of year.
(Photo source: Idaho Department of Fish and Game)