Wolves and eskers: Denning ecology of tundra wolves in Canada's central arctic

Lyle R. Walton, Philip D. McLoughlin, Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada; H. Dean Cluff, Resources, Wildlife and Economic Development, Government of the Northwest Territories, Box 2668, Yellowknife, NT X1A 2P9, Canada; Paul C. Paquet, Conservation Biology Institute, PO Box 150, Meacham, SK S0K 2V0, Canada

We examined the use of eskers by wolves (Canis lupus) because of the recent discovery and development of a diamond resource industry in this remote region. Eskers are likely important habitat for wolves given a lack of suitable den digging material elsewhere. Previous anecdotal evidence suggests that wolves denning on the tundra do so almost exclusively in eskers and other glacio-fluvial habitat such as kames and outwash plains. Repeated use of these den sites by wolves is common. In addition to providing denning sites, wolves use eskers for travel routes, feeding, or resting. Because eskers are comprised of coarse sand and gravel, they are excellent sources of construction material for quarries, airstrips, camps, and roads. Further, eskers are relatively rare landscape features, and their industrial use or removal has potential for land use conflicts with wildlife. If wolves are directly impacted by industrial development, it will likely occur during denning.

We monitored the movements of collared wolves during the denning period to examine if they were associated with eskers. We captured 23 wolves in 18 different packs in 1997 and 1998 throughout a 60,000 km2 study area centered 300 km northeast of Yellowknife, Northwest Territories, Canada. We fitted these wolves with satellite radio-collars to locate den sites, track their movements, and determine fidelity to specific sites. In addition, we radio-collared 24 wolves within these packs with conventional VHF transmitters to assist with monitoring.

Wolves in Canada's central arctic region migrate with the barren-ground caribou (Rangifer tarandus groenlandicus) and this was a major factor in determining wolf movement patterns. However, many wolves did not follow the caribou to the calving grounds, choosing instead to raise their pups further south but still above treeline. We believe this strategy optimizes the availability of caribou to wolves during pup-rearing. Wolves began showing fidelity to a den site on the tundra by late April and often remained at natal den sites for most of the summer. The abandonment of den sites in late summer was influenced by the presence of caribou nearby. Nevertheless, collared wolves remained above treeline until late October, after which they followed caribou to the winter ranges. We do not believe wolf den sites are limiting, although the selection of eskers for natal den sites appears important.