Landscape attributes explain migratory caribou vulnerability to sport hunting

Human disturbances are increasing in Arctic regions and have been suggested as one of the main factors explaining caribou (Rangifer tarandus) decline. The cumulative effects of disturbances may negatively affect caribou habitat use, survival, and population dynamics. Thus, there is a need to evaluate the impact of various human disturbances, especially those that cause direct mortality (e.g., sport hunting). We evaluated the relative importance of caribou and hunter habitat selection and landscape characteristics on caribou vulnerability to sport hunting in northern Quebec, Canada. We used resource selection functions to describe habitat selection of 223 caribou and 87 hunters. We then characterized >169,000 caribou harvest sites recorded over 17 years according to the relative probability of co-occurrence of caribou and hunters, the relative probability of occurrence of hunters only, or the characteristics of the landscape (e.g., distance to human infrastructures, elevation, land cover type). Landscape characteristics better explained caribou vulnerability to sport hunting than habitat selection of caribou and hunters, or their co-occurrence. Caribou were more vulnerable in proximity to hunting infrastructures (e.g., roads, outfitter camps) than elsewhere, but caribou strongly avoided roads. Caribou were also more vulnerable on frozen lakes than in other land cover types. Lakes were, however, avoided by caribou and not selected by hunters. Harvest was more likely in smoother terrain, even if caribou and hunters did not select for this characteristic. We demonstrated caribou were more vulnerable in areas with good accessibility (near roads) or where caribou were easily detectable (lakes, smoother terrain), which also represents areas that were either avoided or not selected by caribou or hunters. This discrepancy between harvest distribution and behaviors of caribou and hunters suggests that harvest may be an opportunistic event where visibility and accessibility increased chances of success for hunters. Managers could use this information to manipulate hunting success according to population estimates and harvest quota by establishing minimal distance to risky areas within which hunting would be prohibited. (c) 2016 The Wildlife Society. We demonstrated that accessibility to the hunting areas, mainly defined by roads and outfitter camps, and visibility are the main factors increasing caribou vulnerability to sport hunting. We recommend that future studies on cumulative impacts consider roads as a human disturbance causing avoidance and as a potential source of mortality due to the increase in accessibility for hunters.