The mule deer (Odocoileus hemionus) is a deer whose habitat is in the western half of North America. It gets its name from its large mule-like ears. The black-tailed deer is considered by some a distinct species though it is classified as a subspecies of the Mule Deer. Unlike its cousin, the white-tailed deer, mule deer are generally more associated with the land west of the Missouri River. The most noticeable differences between whitetails and mule deer are the color of their tails and configuration of their antlers. The mule deer's tail is black tipped. Mule deer antlers are bifurcated, or "fork" as they grow rather than branching from a single main beam (as with white-tails). Each year a buck's antlers start to grow in spring and are shed after mating season from mid-January to mid-April. Mule deer bucks have somewhat more prominent ears than females. Instead of running, mule deer move with a bounding leap (stot), with all four feet coming down together.
The mule deer is the largest of the Odocoileus genus, standing, on the average, 40–42 inches (100–110 cm) at the shoulders and stretching 80 inches (200 cm) or so nose to tail. An adult buck will weigh from 150–300 pounds (68–140 kg) on the hoof, with does averaging 125–175 pounds (57–79 kg). The occasional trophy-sized mule deer buck may weigh in around 500 pounds (230 kg). The Mule Deer does not show marked size variation across its range as does the White-tailed Deer.