Feeding ecology of wolves on barren-ground caribou range in the Northwest Territories
The interrelationship of wolves and barren-ground caribou was studied mainly between 1960 and 1965, although some facets of the study continued until 1968. The work was conducted in spring and summer in the Thelon Game Sanctuary about 450 miles northeast of Fort Smith, N.W.T., with supplementary winter work on caribou winter range north of Yellowknife, N.W.T. and east of Fort Smith. This dissertation reports the results of the study of feeding ecology of tundra wolves. Tagging studies showed that tundra wolves travel great distances and that their movements are associated with those of the barren-ground caribou, their major prey species. Study of the food habits of tundra wolves confirms that, during the winter, they are completely dependent on caribou for food. During the spring and summer the diet of wolves is much more varied than in winter and small rodents, passerine birds, eggs and fish are then resorted to, particularly in areas temporarily devoid of caribou. Caribou calves are subject to heavier predation than other age classes. Caribou of 8 to 9 years and 10 years and older are also heavily preyed on. Wolves kill at least four times as many female caribou as males. Strategy of wolves' attacks on caribou was deduced from tracks and from marks on the body of the prey. Neck and shoulder region of the prey were the favourite locus of attack by wolves. Caribou killed in winter are completely utilized by wolves; in summer, parts of carcasses are often left to scavengers. A short term, high wolf density of one wolf per 6.9 square miles of caribou winter range is described. Studies of food requirements of a colony of captive wolves showed that these wolves could be maintained on an average daily ration per wolf of 3.23 pounds of bison meat and fat and 0.26 pounds of commercial dog food. Weights of three litters of cubs, born in captivity, were recorded weekly. Per cent relative growth rates were calculated and showed no apparent differences in character between the sexes. Mean growth curves for the three litters of cubs were plotted and illustrated rapid early growth of young wolves followed by a reduction in rate of growth.