Why mule deer are declining elsewhere in Montana
While the mule deer population in southeastern Montana is booming, numbers elsewhere in the state—and throughout the West—remain lower than several decades ago. They will likely stay that way. The population decline stems largely from a decrease in quality habitat available to mule deer in central and western Montana caused mainly by:
The spread of conifers: Douglas fir, Rocky Mountain juniper, and other conifers have spread across mountainsides and foothills. The conifers outcompete the forbs, shrubs (such as mountain mahogany, antelope bitterbrush, and sagebrush), and young quaking aspen that mule deer eat. This “conifer expansion” has been caused by decades of fire suppression and reduced tree cutting on federal, state, and private lands.
Competition from elk and whitetails: Elk and mule deer share much of the same habitat. Though their diets don’t overlap completely, an elk eats three times more than a mule deer and is better able to reach browse in deep snow. In much of Montana’s prime mule deer country, elk numbers are now three or four times greater than they were in the 1980s, and they have taken over areas previously dominated by mule deer. For instance, in several hunting districts in southwestern Montana, winter elk counts have increased from a total of about 4,000 in 1980 to more than 17,000 in 2015. Mule deer numbers in those same hunting districts have declined by 64 percent.
Mule deer also face competition from white-tailed deer, which generally do better in areas altered by human development.
“The increase in conifers, elk, and whitetails in mule deer country is the new normal,” says John Vore, chief of FWP’s Game Management Bureau. “We’ll never have muley numbers in western Montana like we did in the 1980s unless we can magically change all that and make everything like it was 40 years ago.”