Abstract

As human encroachment in natural habitats increases ubiquitously, understanding its impacts on wildlife is crucial. We investigated the impacts of anthropogenic disturbances (i.e. clearcuts and roads) on the movements of the woodland caribou, a threatened species inhabiting the highly managed southern fringe of the boreal forest. We used GPS telemetry data from 49 females followed between 2004 and 2010 in the Saguenay-Lac-Saint-Jean region (Québec, Canada). Space use was evaluated at a coarser scale using individual home-range size as a function of observed disturbance levels within home ranges. Individuals first expanded their home ranges alongside increases in disturbance levels, yet subsequently shifted their behaviour when certain disturbance thresholds were exceeded by contracting home ranges and potentially trapping individuals in sub-optimal habitats. Fine-scale movements were investigated using a use-availability design contrasting observed and random steps (i.e. straight-line segment between successive locations). Individuals, although mostly avoiding disturbances, nonetheless regularly came in close contact with them. As a consequence, females modulated their movements daily and annually, avoiding disturbances predominantly during periods of higher vulnerability (i.e. calving, early and winter) during the day, while using them in periods of higher energy requirements (i.e. spring, summer and rut) during dusk/dawn and at night. Additionally, individuals altered their behaviour depending on the context in which they were moving, either relocating or remaining in altered habitats as disturbance levels increased. Our results suggest that current disturbance levels observed in the boreal forest cause behavioural shifts that may compel females to use suboptimal habitats, likely threatening the persistence of woodland caribou populations in North-American forests.