Woodland Caribou

Rangifer tarandus caribou

Description

Caribou are intermediate in size between deer and elk. The largest males from Canada and Alaska are 8 ft (2.4 m) long, stand 4 ft (1.2 m) high at the shoulder, and weigh as much as 600 lbs. (272 kg); adult females weigh between 200 and 300 lbs. (91-136 kg). Caribou are distinguished from other deer by larger hooves, broader muzzles, and distinctive antlers that appear somewhat flattened in cross-section. Male antlers rise in sweeping arcs and display numerous points and shovels. Female antlers are inconspicuous. Mature males have a shaggy mane beneath the neck. Coloration is dark chocolate brown with white patching on neck and rump.

Four living subspecies of North American caribou are included under the classification of Rangifer tarandus. Three of the subspecies inhabit the tundras of the far north. The woodland subspecies (R. t. caribou ) ranges across most of central Canada.

Behavior

The woodland caribou does not form large herds but tends to congregate in family groups of three to 10 animals. Although it has a wider diet than most other deer, winter foraging is limited almost exclusively to lichens growing on subalpine fir and spruce trees. The caribou's splayed feet enable it to move easily over deep snow, and depending on snow depth, it may be able to forage 5-20 ft (1.5-6 m) above ground level. In late fall and early winter, it browses on low evergreen shrubs, mushrooms, grasses, and sedges.

Adult bulls are solitary for most of the year but seek out bands of females and immatures in September when the female is in rut. Each mature bull attracts a group of six to 10 cows and calves, which he vigorously defends from the advances of younger bulls. Females begin breeding at three or four years of age, and, thereafter, more than 80% of females bear a single calf each season. After several weeks of intense feeding in early spring, pregnant females climb more than 2,000 ft (600 m) to the highest ridgetops. The cow typically chooses the most severe and isolated habitat she can find to bear her calf.

This behavior is thought to be an adaptation to predation by brown bears and grizzlies, which move to lower elevations in spring. Although adult caribou are not threatened by bears, new calves are easy prey. Annual calf mortality, due to predation, severe weather, or malnutrition, ranges from 40-70%.

Habitat

The woodland caribou inhabits rugged mountainous regions and prefers dense stands of fir and spruce. It moves seasonally, spending most of the winter at elevations up to 6,000 ft (1,830 m), feeding on lichens until the snow begins to melt in the spring. It then descends to lower elevations (1,900 ft, or 580 m) to feed on new vegetation. As summer progresses, it follows the line of melting snow back up the mountain, feeding on tender plant growth. In late autumn and early winter, it again descends to browse in the cedar-hemlock vegetation zone.

Distribution

When North America was first settled, the woodland caribou ranged across Canada and south into the northern portion of the United States from New England to Washington state. Deforestation and hunting eliminated the animal from New England, the Great Lakes states, and North Dakota by the early 1900s. A remnant U.S. population survived in the Cabinet and Yaak Mountains of Idaho and Montana until the 1950s. A once-extensive population in the Selkirk Mountains of eastern Washington and Idaho was reduced to about 100 animals by 1960.

Today, an estimated 1.1 million caribou still range across North America, but most are in the wilderness areas of western Canada and Alaska. In 1963 British Columbia Highway 3 was completed through the heart of the woodland caribou's range there. Since that time the number of road kills of caribou attracted by winter road salt has increased.

In the United States, the numbers of the woodland caribou are quite low, though increasing. From a low of approximately 25 individuals when it was listed as Endangered in 1984, by mid-1997 the population had more than doubled, to a high of 59 animals, occurring in three herds in the Selkirk Mountains of Idaho, Montana, Washington and southern British Columbia. The increase in numbers is due in large part to an international transplant effort, which relocates healthy animals from abundant Canadian herds to the Selkirk Mountains. These animals represent the last free-ranging caribou in the lower 48 states.

Threats

The major reason for caribou decline in the Selkirks has been habitat alteration caused by logging, mining, and fire. Large tracts of a critical habitat component—old-growth cedar-hemlock forests— has been significantly reduced by logging. Destructive forest fires have occurred periodically. High winds in 1950, and again in 1981, felled large stands of spruce, fir, and hemlock trees throughout the range. These disasters were followed by invasions of spruce bark beetles that killed many trees. Logging operations moved to higher elevations to salvage diseased trees and deforested large areas.

The states of Idaho and Washington are cooperating with the U. S. Fish and Wildlife Service (FWS) to manage remaining caribou habitat in the Selkirk Mountains. The first goal of recovery efforts is to expand the herd to about 100 animals. Currently implemented management strategies fall into three categories: animal protection, habitat protection, and herd enhancement.

Although poaching is not a major problem— about one animal per year is lost to illegal hunting— the impact on such a small herd of animals can be severe, particularly if females are killed. Most hunting deaths are unintentional; unaware that caribou are in the area, hunters assume that they are legally shooting a deer or elk. To counter this ignorance, the states and the FWS have implemented a public information campaign to inform hunters of the range and importance of the caribou.

Predation is a larger problem than once thought. Studies conducted during the 1980s revealed that the occurrence of mountain lions and coyote in the range of the Selkirk caribou leads to some loss of life among the rare herds.

Conservation and Recovery

Much of the caribou's habitat in the Selkirk Mountains falls under the authority of the U.S. Forest Service, the states, or the British Columbia Forest Service. To preserve habitat, these agencies have undertaken a review of forestry practices and have recommended a program of logging that does not eliminate either the animal's cover or its winter feed. Caribou habitat management guidelines developed by an interagency team are used by the U.S. Forest Service, British Columbia Ministry of Environment, and Idaho Department of Lands to design timber sales in caribou habitat. In addition, biological studies have been initiated to help better define the species' specific habitat requirements.

Research into the feasibility of augmentation has led to the translocation of new caribou from Canada into the Selkirk range. To enhance the existing herd, 24 woodland caribou from a Canadian herd were translocated to the panhandle of Idaho in 1987. Twenty-four more animals were released near the same place in 1988, and the state of Idaho plans a third translocation of Canadian animals in 1989.

In April 1996, 19 woodland caribou were translocated from British Columbia. Since their release, the relocated caribou have traveled throughout the recovery area, some joining the caribou that were still present within the ecosystem. By October 1996, at least one calf had been born and there had been two deaths, probably caused by predation. The 1996 translocation effort was the first phase of a three-year project. The second phase, begun in the spring of 1997, involved the translocation of 13 caribou from western Canada to the eastern Washington portion of the Selkirk Mountain Recovery Area. Translocated animals are monitored annually to determine the course of future recovery efforts.

The 1994 revised Recovery Plan notes that recovery criteria calls for management for an increasing population, and management of at least 442,317 acres (179,000 hectares) of habitat to support a self-sustaining caribou population. The plan calls for the establishment of a third herd in the western Selkirks in Washington, the determination and establishment of caribou recovery goals and objectives, and the public and agency personnel involvement and in the recovery process.

Contact

Regional Office of Endangered Species
U.S. Fish and Wildlife Service
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232
http://pacific.fws.gov/

References

Bergerud, A. T. 1974. "Decline of Caribou in North America Following Settlement." Journal of Wildlife Management 38:757-770.

Miller, F. L. 1982. "Caribou: Rangifer tarandus." In J.A. Chapman and B. A. Feldhamer, eds., Wild Mammals of North America. Johns Hopkins University Press, Baltimore.

Scott, M. 1985. "The Woodland Caribou." In Audubon Wildlife Report 1985/1986. National Audubon Society, Academic Press, New York and London.

U.S. Fish and Wildlife Service. 1985. "Selkirk Mountain Caribou Management Plan." U.S. Fish and Wildlife Service, Portland.

U.S. Fish and Wildlife Service. 1994. "Revised Recovery Plan for the Selkirk Mountain Caribou Management Plan." U.S. Fish and Wildlife Service, Portland.

U.S. Forest Service. 1985. "Selkirk Mountains Caribou Herd Augmentation: A Cooperative Interagency Plan." Idaho Panhandle National Forests, Coeur d'Alene, Idaho.