Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Woodland caribou (Rangifer tarandus caribou) populations are declining worldwide, and predation is considered their most important limiting factor in North America. Caribou are known to reduce predation risk by spacing themselves away from predators and alternative prey. This strategy is now compromised by forestry activities that reduce the amount of suitable caribou habitat and trigger an increase in densities of alternative prey and predators. Our objective was to investigate the influence of predation risk and food availability on selection of a calving location by woodland caribou at three different spatial scales (from coarse to fine: annual home range, calving home range, and forest stand scales) in the boreal forest of Québec, Canada. Using GPS telemetry, we identified calving locations and assessed those using Resource Selection Functions. We determined habitat characteristics using digital ecoforest and topographic maps at the annual and calving home range scales, and with vegetation surveys at the forest stand scale. Caribou selected calving locations located at relatively high elevation and where road density was low, both at the annual and calving home range scales. Within the annual home range scale, they also selected calving locations where the proportion of young and old cutovers was lower than in random areas of similar size. At the forest stand scale, females calved away from roads and young cutovers, using stands where the basal area of black spruce and balsam fir trees was low. At this fine scale, females still selected calving locations located at a relatively high elevation and where the availability of food resources was lower than in random areas located within the same habitat type. The selection of a calving location was driven by predation risk from the largest to the finest spatial scale. Therefore, our results suggest that females may not be able to lower predation risk at larger scales, despite general avoidance of roads and cutovers. We recommend amalgamating all forestry activities within intensive management zones in order to spatially isolate large patches of suitable calving habitat from anthropogenic disturbances. If not possible, we recommend concentrating forestry activities in low-lying areas since caribou consistently selected for relatively high elevations at all scales.