Coyote predation and habitat segregation of white‐tailed deer and mule deer

Predation has been proposed as a major factor maintaining segregation among species of ungulates, but predator–prey interactions have not been observed to test this idea directly. Here, observations of coyote (Canis latrans) packs hunting deer are used to show that mule deer (Odocoileus hemionus), which typically stand high on slopes and on rugged terrain, increased both their risk of being encountered and attacked by coyotes by standing low rather than high on slopes. The risk incurred at certain heights was not fixed: a mule deer's risk of being approached by coyotes was also affected by the height of other mule deer groups present during the same hunt. White‐tailed deer (O. virginianus), which typically use gentle terrain, were not similarly disadvantaged by remaining low on slopes or on flat terrain. When confronted by coyotes, mule deer moved to and up slopes, whereas white‐tails moved down and away from slopes. Species differences in behavior were independent of starting position and were observed for animals in mixed‐species groups. Unlike their response to coyotes, feeding preferences or competition did not lead mule deer to use rugged habitats: mule deer moved down and left slopes to feed, bringing them closer to white‐tails. These results suggest that coyote predation contributes to the habitat segregation of white‐tails and mule deer (1) by selective predation against mule deer but not white‐tails in gentle habitats and (2) by eliciting differing antipredator behavior that increases their segregation. Unlike prey involved in other examples of predator‐mediated resource partitioning, white‐tails and mule deer are similar in size and morphology. Contrasting antipredator strategies, specifically, their ability to avoid predation using flight or confrontation, are likely to explain why the species differ in their behavior and in their risk on gentle terrain.