Habitat

Southern-most caribou: a South Georgian caribou with velvet-covered antlers.

A few caribou from Norway were introduced to the South Atlantic island of South Georgia in the beginning of the 20th century. Today there are two distinct herds still thriving there, permanently separated by glaciers. Their total numbers are no more than a few thousand.

Anatomy

The weight of a female varies between 60 and 170 kg (132 - 375 lb). In some subspecies of reindeer, the male is slightly larger; in others, the male can weigh up to 300 kg (661 lb). Both sexes grow antlers, which (in the Scandinavian variety) for old males fall off in December, for young males in the early spring, and for females, summer. The antlers typically have two separate groups of points (see image), a lower and upper. Domesticated reindeer are shorter-legged and heavier than their wild counterparts. The caribou of North America can run at speeds up to 80 km/h (50 mph) and may travel 5,000 km (3,000 mi) in a year.

Caribous are ruminants, having a four-chambered stomach. They mainly eat lichens in winter, especially reindeer moss. However, they also eat the leaves of willows and birches, as well as sedges and grasses.

Caribous have specialized noses featuring nasal turbinate bones that dramatically increase the surface area within the nostrils. Incoming cold air is warmed by the animal's body heat before entering the lungs, and water is condensed from the expired air and captured before the deer's breath is exhaled, used to moisten dry incoming air and possibly absorbed into the blood through the mucous membranes.

Caribou hooves adapt to the season: in the summer, when the tundra is soft and wet, the footpads become spongy and provide extra traction. In the winter, the pads shrink and tighten, exposing the rim of the hoof which cuts into the ice and crusted snow to keep the animal from slipping. This also enables them to dig down (an activity known as "cratering") through the snow to their favorite food, a lichen known as reindeer moss.

The reindeer coat has two layers of fur, a dense woolly undercoat and longer-haired overcoat consisting of hollow, air-filled hairs. A caribou or reindeer swims easily and quickly; migrating herds will not hesitate to swim across a large lake or broad river.

Subspecies

Herd of Barren-ground Caribou on the Thelon River

• Woodland Caribou, or forest caribou, once found in the North American taiga (boreal forest) from Alaska to Newfoundland and Labrador and as far south as New England and Washington. Woodland Caribou have disappeared from most of their original southern range and are considered "threatened" where they remain, with the notable exception of the Migratory Woodland Caribou of northern Quebec and Labrador, Canada. A herd is protected in the Caribou Mountains in Alberta.
• Finnish Forest Reindeer, found in the wild in only two areas of the Fennoscandia peninsula of Northern Europe, in Finnish/Russian Karelia, and a small population in central south Finland.
• Porcupine caribou or Grant's Caribou which are found in Alaska, the Yukon and the Northwest Territories of Canada.
• Barren-ground Caribou, found in Nunavut and the Northwest Territories of Canada and in western Greenland.
• Peary Caribou, found in the northern islands of the Nunavut and the Northwest Territories of Canada.
• Svalbard Reindeer, found on the Svalbard islands of Norway, is the smallest subspecies of reindeer.
• Mountain/Wild Reindeer, found in the Arctic tundra of Eurasia, including the Fennoscandia peninsula of Northern Europe.

This text is available under the terms of the GNU Free Documentation License.