The elk ('Cervus canadensis'), also known as the wapiti, is one of the largest species within the deer family, 'Cervidae', and one of the largest terrestrial mammals in its native range of North America, as well as Central and East Asia. It is often confused with the larger 'Alces alces', which is called moose in North America, but called elk in British English.

Elk were long believed to belong to a subspecies of the European red deer ('Cervus elaphus'), but evidence from many mitochondrial DNA genetic studies beginning in 1998 shows that the two are distinct species. The reindeer is an arctic and subarctic-dwelling deer of the species 'Rangifer tarandus', with a number of subspecies. The roe deer ('Capreolus capreolus'), also known as the roe, western roe deer, or European roe, is also a species of deer.

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