The reindeer (Rangifer tarandus), also known as the caribou in North America, is a deer from the Arctic and Subarctic, including both resident and migratory populations. While overall widespread and numerous, some of its subspecies are rare and one (or two, depending on taxonomy) has already gone extinct.
Reindeer vary considerably in color and size. Both sexes grow antlers, though they are typically larger in males. There are a few populations where females lack antlers completely.
Wild reindeer hunting and herding of semi-domesticated reindeer (for meat, hides, antlers, milk and transportation) are important to several Arctic and Subarctic people. Even far outside its range, the reindeer is well known due to the myth, probably originating in early 19th century America, in which Santa Claus's sleigh is pulled by flying reindeer, a popular element of Christmas. In Lapland, reindeer pull pulks.
The reindeer is a widespread and numerous species in the northern Holarctic, being present in both tundra and taiga (boreal forest). Originally, the reindeer was found in Scandinavia, eastern Europe, Russia, Mongolia, and northern China north of the 50th latitude. In North America, it was found in Canada, Alaska (USA), and the northern conterminous USA from Washington to Maine. In the 19th century, it was apparently still present in southern Idaho. It also occurred naturally on Sakhalin, Greenland, and probably even in historical times in Ireland. During the late Pleistocene era, reindeer were found as far south as Nevada and Tennessee in North America and Spain in Europe. Today, wild reindeer have disappeared from many areas within this large historical range, especially from the southern parts, where it vanished almost everywhere. Large populations of wild reindeer are still found in Norway, Finland, Siberia, Greenland, Alaska, and Canada.
The George River reindeer herd in the tundra of Quebec and Labrador in eastern Canada, once numbered world’s largest 8-900,000 animals, stands December 2011 at 74,000 – a drop of up to 92% because of Iron-ore mining, flooding for hydro-power and road-building.
Domesticated reindeer are mostly found in northern Fennoscandia and Russia, with a herd of approximately 150-170 reindeer living around the Cairngorms region in Scotland. The last remaining wild tundra reindeer in Europe are found in portions of southern Norway.
A few reindeer from Norway were introduced to the South Atlantic island of South Georgia in the beginning of the 20th century. The South Georgian reindeer total some 2600 animals in two distinct herds separated by glaciers. Although the flag and the coat of arms of the territory contain an image of a reindeer, they are under threat of eradication because of the environmental damage they cause. Around 4000 reindeer have been introduced into the French sub-Antarctic archipelago of Kerguelen Islands. East Iceland has a small herd of about 2500–3000 animals.
Caribou and reindeer numbers have fluctuated historically, but many herds are in decline across their range. This global decline is linked to climate change for northern, migratory caribou and reindeer herds and industrial disturbance of caribou habitat for sedentary, non-migratory herds.