Black-tailed deer or blacktail deer occupy coastal regions of western North America. There are two subspecies, the Columbian black-tailed deer (Odocoileus hemionus columbianus) which ranges from the Pacific Northwest of the United States and coastal British Columbia in Canada to Santa Barbara County in Southern California, and a second subspecies known as the Sitka deer (O. h. sitkensis) which is geographically disjunct occupying from mid-coastal British Columbia up through southeast Alaska, and southcentral Alaska (as far as Kodiak Island). The black-tailed deer subspecies are about half the size of the mainland mule deer (Odocoileus hemionus hemionus) subspecies, the latter ranging further east in the western United States.

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