Deer GPS and animal-borne camera data showing effects of gray wolves on niche overlap between mule and white-tailed deer in eastern Washington state

Predators may alter niche overlap between prey species by eliciting divergent anti-predator behavior. Accordingly, we exploited heterogeneous gray wolf (Canis lupus) presence in Washington, USA, to contrast patterns of resource and dietary overlap between mule (Odocoileus hemionus) and white-tailed deer (O. virginianus) at sites with and without resident packs. Mule deer run (stot) in a way that is less effective as a means of fleeing from predators than the galloping gait of white-tailed deer. Consequently, mule deer manage risk from coursing predators like wolves by avoiding encounters, whereas white-tailed deer respond to such predators by exploiting areas where they are most likely to escape pursuit. Thus, under the “refuge partitioning hypothesis” whereby predators reduce prey niche overlap by eliciting use of different refugia, we predicted wolf exposure to (i) decrease resource and dietary overlap between these ungulates, and (ii) induce segregation consistent with each species u...