Caribou (North America)

Rangifer tarandus

Caribou refers to any of several North American subspecies, ecotypes, populations, and herds of the species ''Rangifer tarandus''. In North America caribou range in size from the smallest, the Peary caribou, to the largest, the boreal woodland caribou. The North American range of caribou extends from Alaska, through the Yukon, the Northwest Territories, Nunavut, into the boreal forest and south through the Canadian Rockies and the Columbia and Selkirk Mountains. Barren-ground, Porcupine and Peary caribou live in the tundra while the shy Woodland caribou, prefers the boreal forest. Two major subspecies in North America, the ''R. t. granti'' and the ''R. t. groenlandicus'' form large herds and undertake lengthy seasonal migrations from birthing grounds, to summer and winter feeding grounds in the tundra and taiga. The migrations of ''R. t. granti'' Porcupine herds are among the longest of any terrestrial mammal. Barren-land caribou are also found in western Greenland, but the larger herds are in Alaska, the Northwest Territories and Nunavut.

The circumpolar species itself, ''Rangifer tarandus'', at a global level, is listed by the International Union for Conservation of Nature "as Least Concern due to a wide circumpolar distribution and presumed large populations." The populations of subspecies, ecotypes, populations and herds of caribou in North America are in decline and one subspecies, the iconic boreal woodland caribou, has been listed by COSEWIC as threatened since 2002.

The George River caribou herd , in the Ungava region of Quebec and Labrador in eastern Canada was once the world's largest herd with 800 000–900 000 animals. By 2012 the herd numbered 27 600 and declined to 14 200 animals in 2014.

The meta-population of the more sedentary subspecies ''R. t. caribou'' or Woodland caribou spans the boreal forest from the Northwest Territories to Labrador. They are shy animals whose main food source is arboreal lichens of the mature forests and mainly live in marshes, bogs, lakes, and river regions. Since it takes hundreds of years for a biomass of tree lichen to be adequate to sustain boreal woodland caribou populations, deforestation is a major factor in the decline of their numbers. The historic range of the boreal woodland caribou covered over half of present-day Canada, stretching from Alaska to Newfoundland and Labrador and as far south as New England, Idaho, and Washington. The smallest subspecies in North America, the Peary Caribou is found in the High and Low Arctic, in the Northwest Territories—particularly, Banks Island and in Nunavut—particularly, Baffin Island.

The caribou is a specialist that is well adapted to cooler climates with hollow-hair fur that covers almost all of its body including its nose, and provides insulation in winter and flotation for swimming. Caribou can reach a speed of 60–80 km/h . Young caribou can already outrun an Olympic sprinter when only a day old. The caribou's favourite winter food is fruticose deer lichen. Seventy percent of the diet of woodland caribou consists of arboreal lichen which take hundreds of years to grow and are therefore only found in mature forests.

Although there are many variations in colour and size, ''Canadian Geographic'' magazine states that in general, barren-ground caribou have larger antlers than the woodland caribou subspecies. Barren-ground caribou have large distinguishing white patches of fur that extend beyond the neck onto the back, a white muzzle and a face that is darker than the rest of the body. Their fur is sandy-beige in winter and light brown in summer. The woodland caribou have a wider more compact body and wider antlers. The coat is a rich dark brown in summer and dark grey in winter. Both the barren-ground and woodland caribou often have white "socks" above their hooves. On average the male weighs 90–110 kg and measures 0.9–1.7 m in shoulder height. The Woodland caribou are the largest and the Peary caribou the smallest. The largest Alaskan male Porcupine caribou can weigh as much as 310 kilograms .

Female caribou can live up to 17 years and male caribou for four years less.

Both sexes grow antlers, though in a some Woodland caribou populations, females lack antlers completely. Antlers are larger in males.

Caribou are an integral part of First Nations and Inuit oral histories and legends including the Gwich'in creation story of how Gwich’in people and the caribou separated from a single entity.