Endangered Status

The Woodland Caribou, a subspecies of the Caribou, is on the U.S. Endangered Species List. It is classified as endangered in Idaho and Washington. The Woodland Caribou once ranged across much of the northern U.S., from Washington to Maine. Today, only one small herd remains south of Canada, in the Selkirk Mountains of northeastern Washington and northern Idaho. Hunting and development encroaching upon their habitat contributed to the decline of these animals. Today accidental shootings and disturbance by snowmobilers continue to threaten the herd.

Habitat

Tundra and taiga; farther south, where lichens abound in coniferous forests in mountains.

Range

Alaska and much of Canada south through British Columbia to e Washington and n Idaho; also n Alberta and northern two-thirds of Manitoba and Saskatchewan; in the East, most of Canada south to Lake Superior and east to Newfoundland.

Discussion

The Caribou of North America, now considered to be the same species as the Reindeer of Europe and Asia, is among the most migratory of all mammals. It is the only cervid that lives year-round north of the tree line in some of the harshest habitat in North America. The gregarious Caribou usually forms a homogeneous band of bulls, or of cows with calves and yearlings, but may also gather in groups numbering up to 100,000 of both sexes and all ages in late winter before the spring migration. As spring proceeds, herds begin to move northward. Females move more rapidly, and soon some of the juveniles drop back, especially if the snow is deep; they will join the bulls, who travel more slowly. The cows spread out as they reach the area for calving, which takes place in mid-May through early July. The newborn calf is well developed, able to stand in about 30 minutes, run some distance after 90 minutes, and keep up with the herd within 24 hours. It begins to eat solid foods at two weeks, but may continue to nurse into the winter.

In October and November, the rut begins; the bulls join the cow/juvenile groups, where they remain until cows become receptive. Mating occurs either at that time, in the early stages of the southward migration, which varies with location, or immediately after fawning. The polygamous bull chases the female, who flees ahead of him. Pursuit is often interrupted by fights with other males. A male may rush about among several cows, thrashing bushes with his antlers and battling other bulls. However, a male actually pursues only one female at a time. After the rut, the animals move south to the winter range; adult bulls often separate at this time from the cow/juvenile group. Different herds move in different ways in order to reach summer, winter, calving, and rutting grounds with adequate food, water, and protection from predators. The most impressive migrations are by the Caribou living on the tundra in the northwest, often called the “Barren Ground Caribou.”

Especially active in the morning and the evening, the Caribou can run at speeds of nearly 50 mph (80 km/h), but cannot maintain such a pace for very long. The animal’s spongy footpads provide traction and good weight distribution on boggy summer tundra; in winter, when the pads have shrunk and hardened, and are covered with tufts of hair, the hoof rim bites into ice or crusted snow to prevent slipping. The Caribou is also a good swimmer. It swims with nearly a third of its body above water, the air-filled hollow hairs of its coat giving it great buoyancy. In summer, to avoid heat and insects, the Caribou often lies on snowbanks on the north side of hills; in winter, it suns on frozen lakes. In early spring, the antlers begin to grow; they are lost shortly after rutting. The female retains her antlers through the winter and loses them about the time the calves arrive. In summer, the Caribou feeds on lichens, mushrooms, grasses, sedges, and many other green plants, twigs of birches and willows, and fruit; it also competes with rodents for dropped antlers, a source of calcium. In winter, lichens are the chief food, supplemented by horsetails, sedges, and willow and birch twigs. Food intake is much reduced in winter, and the animal then loses weight.

The Caribou needs high-quality forage in summer to supply the energy necessary for reproduction, growth, and winter survival. Cows with insufficient energy reserves will probably not breed, but will build reserves and breed the following year. In the fall, the bull Caribou fattens up to sustain himself through the rigors of the rut, when he seldom eats. Usually quiet, the Caribou may give a loud snort, and herds of snorting animals may sound like pigs.  Biting flies and other insects can be a major problem for Caribou in some areas. In years of major outbreaks, the Caribou will seek snowdrifts, windy ridges, water, or other areas with few insects. Sometimes there is nothing the animal can do but run around wildly in an attempt to avoid them. Chief predators are humans and wolves, although Grizzly Bears, Wolverines, Lynx, and golden eagles may take a few Caribou, particularly the young. The Caribou has been a major source of food and clothing for native people of the far north.