The range protects one of most endangered ecosystems in North America, the intermountain bunchgrass prairie. In addition to the 350 to 500 bison on the Bison Range, many other mammal species may be seen on the refuge, including coyote, black bear, elk, mule deer, bighorn sheep, white-tailed deer, pronghorn, mountain cottontail, Columbian ground squirrel, muskrat, yellow-pine chipmunk, badger, and cougar. Over two hundred bird species have been seen on the refuge. The Bison Range also contains many plant species, including the bitterroot, ponderosa pine, and buffalo grass.