Territoriality Modulates the Effect of Conspecific Encounters on the Foraging Behaviours of a Mammalian Predator

The probability of encountering conspecifics shapes animal behaviour, particularly for territorial individuals which often increase vigilance and scent marking when approaching home range boundaries. However, whether the foraging behaviours of territorial predators also vary with the probability of encountering neighbouring territory owners is poorly understood. We monitored 23 Arctic foxes occupying neighbouring home ranges during 2 years of contrasting resource availability on Bylot Island, Nunavut, Canada. First, based on simultaneous GPS tracking of individuals, we established which individuals used a territory by estimating the spatial distribution of the probability of encountering a neighbour within their home range. Second, using GPS and accelerometry data, we evaluated if the probability of encountering a neighbour influenced foraging behaviours, and whether this relationship differed between territorial and non-territorial individuals. When resources were abundant, only breeding individuals excluded other foxes from a part of their home range and were thus territorial. When resources were rare, none of the foxes reproduced, and all but one were territorial. Non-territorial individuals were less likely to cache prey in areas with a high probability of encounter, possibly to reduce cache pilfering. Territorial individuals were slightly more likely to cache prey as the probability of encountering neighbours increased, suggesting that they do not actively avoid interactions while foraging. We suggest Arctic foxes use different tactics to secure resources based on their degree of territoriality. The presence of non-territorial predators, whose home ranges overlap those of territorial neighbours, may influence the distribution of predation risk by creating zones where predator density is high, potentially influencing predator-prey interactions.