Wolves and Caribou
- Grades: 6–8, 9–12
The information in this section was provided by various printed publications and biologist Mark Williams of the Department of Renewable Resources, Government of the Northwest Territories, Canada.
The IAP team is near the northern shore of Ellesmere Island. Although barren-ground caribou tend to migrate only as far as north Baffin Island in the summer, the Peary caribou and the Arctic wolf populations range as far north as 83 degrees N, including Ellesmere and the High Arctic. Nearly all caribou herds are accompanied by wolves most of the year, thus the physical and social life-cycles of these two animals are closely interconnected.
Arctic wolves tend to be smaller than timber or tundra wolves because of harsher conditions and sparse food population. Adult males average about 35 kg in weight and 1.5 meters in length from nose to tip of the tail, while adult females average 30 kg and 1.4 meters. Primarily, the wolves in the Arctic are white or cream and the coat is thick, composed of long, coarse outer hair and shorter, soft fur underneath. (From our previous descriptions of other animals, ranging from sled dogs to muskox, it is clear that many different species have evolved a similar layering of fur for an extremely cold environment.) Wolves mate in late March and the females produce litters of four to seven pups in late May or early June. In a den that the mother has dug herself, or in many cases refurbished, the pups are born blind and deaf. Pups remain with their pack for at least the first year to survive. While many wolves leave the pack over their second summer or winter — usually because of rivalry for mates — some remain with their pack for several years.
Peary caribou migrate seasonally among the Arctic islands where they spend their lifetime. Most caribou vary in size according to their subspecies, and in keeping with other Arctic wildlife, the Peary herds tend to be smaller than other types of caribou in the Northwest Territories. Adult males may possibly reach 100 cm high at the shoulder and 100 kg in weight. Their coat changes color since they go through a molting process in early summer: caribou can appear black, brown, patchy, or even silver depending on the season. Most female caribou (cows) give birth to their calves during the first two weeks in June. The cows band together in groups in high, rocky areas where lichens and grasses are more abundant, and where they will be more protected from wolves. Within an hour of being born, a calf can stand and even follow its mother, and the two have bonded closely in order to distinguish each other among the herd.
Arctic wolves hunt both caribou and muskoxen. Because wolves prey on animals much larger than themselves, they have had to develop rather sophisticated methods of catching their prey. Caribou try to protect themselves from wolves by sleeping on frozen lakes in the winter, where they can see wolves before they get too close. A healthy caribou can usually outrun a wolf across the hard-packed snow on a frozen lake, or across the tundra in the summer. In the summer, caribou swim out into lakes if they cannot outrun a wolf. Caribou are very good swimmers due to their hollow hair that provides buoyancy, and their large, splayed hooves that provide them with efficient "paddles." Although wolves will swim, they are not nearly as fast as caribou. The wolves rely on surprise, strategy, and group hunting to compensate for their lack of speed.
Caribou can live for up to 18 years under ideal conditions, but very few live to that age in the wild. Very few caribou are found older than twelve in the wild, and the average age would be around four. Wolves have a life span similar to that of domestic dogs, and can live up to 16 years in captivity. However, very few wolves over six years of age are found in the wild, and their average age is around three.
Both caribou and wolves have a tenuous existence in the Arctic. Their populations fluctuate with environmental conditions and the amount of human intervention they are exposed to, but both animals remain highly resilient and an extremely important part of the ecosystem.
For more information about animals in the Canadian Arctic region, you can contact:
Department of Renewable Resources
Government of the Northwest Territories
NWT X1A 2L9