Mule deer are social animals that typically stay in groups. They live in a multi-generation family of related females and their offspring. Bucks older than yearlings often group together or remain solitary. NPS Photo / James Ecklund. Altogether, 67 mammal species are known to be native to the area, but grizzly bears, gray wolves and bison were locally extirpated in the 19th and early 20th centuries. The lynx and wolverine are either extirpated or extremely rare.