The mule eer (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. Its closest relative is the black-tailed deer (considered a subspecies of 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 muleys are the color of their tails and configuration of their antlers. The mule deer's tail is black tipped. Mule deer antlers "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.