Species of medium-sized, gregarious deer of western North America distinguished by large ears, striking pelage markings, large antlers, a distinctive leaping run, scent glands, a black-tipped tail, male antlers that are bifurcated, or "fork" as they grow rather than as a white-tailed deer's branching from a single main beam. Recent DNA analysis indicates that the mule deer is apparently a rather recent form that arose from hybridization of female white-tailed and male black-tailed deer.