The mule deer (Odocoileus hemionus) or black-tailed deer is a deer indigenous to western North America, named for its large mule-like ears. The most noticeable differences between whitetails and mule deer are the size of their ears, the color of their tails, and the configuration of their antlers. The mule deer's tail is black-tipped, whereas the whitetail's is not.

The large carnivores such as mountain lions, black bears and wolves are natural predators; the Mule deer using their high alertiveness and natural camouflage for survival. Although capable of running, mule deer often prefer to stot, with all four feet coming down together. They forage on herbaceous plants, but also various berries and feed on grasses mainly through winter.