The blacktail and the whitetail are different species. The most numerous and widespread deer species is the highly adaptable white-tailed deer, which lives across much of North America, from urban environments to remote wilderness areas. Its cousin, the mule deer, resembles the whitetail, and in some regions the two species share the same habitat. Black tail deer and mule deer are both primarily found in the Western United States and Canada, on the west side of the continental divide. What’s the difference between a black-tailed deer and a mule deer? Key deer), I was thrilled to discover that Oregon has a boat-load of ungulates of varying shapes and sizes. Black-tailed deer once ranged at least as far as Wyoming. While the black tail is a subspecies of mule deer, there is a noticeable difference between the two. The blacktail deer ( Odocoileus hemionus) split off from the whitetail at some time in the past, thought to be a million years ago or more. Whitetail are the oldest living species of deer at 3.5 million years old. January 26, 2016 January 27, 2016 Having moved from the east coast and a state in which the ungulate (hoofed animals) population was limited to small white-tailed deer and smaller white-tailed deer (i.e. In Francis Parkman's The Oregon Trail, an eyewitness account of his 1846 trek across the early West, while within a two-days ride from Fort Laramie, Parkman writes of shooting what he believes to be an elk, only to discover that he has killed a Black-tailed Deer.