The spatial relationship between predator and prey is often driven by a behavioral response race, in which prey avoid predators while predators attempt to track prey. Limitation of particular habitat types can create a “spatial anchor” for either prey or predator, influencing the outcome of the response race. Prey habitat constraints should make prey predictable, favoring predators, whereas predator hunting domain constraints should make predators predictable, favoring prey. However, when predator and prey require identical habitat features, risk and reward become spatially conflated, creating a joint spatial anchor and confusing the outcome of the behavioral response race. We test two alternative hypotheses regarding the relationship between habitat distribution and predator-prey interactions: 1) a joint spatial anchor will benefit predators, increasing spatial overlap and exploitation rates; and 2) a joint spatial anchor will benefit prey, decreasing spatial overlap and exploitation rates. Specifically, we evaluate the interactions of the puma (Puma concolor) and its primary camelid prey, the vicuña (Vicugna vicugna), in sites with and without a joint spatial anchor in San Guillermo National Park, Argentina.
Results/Conclusions
We find that puma-vicuña spatial correlation is positive when predator and prey share a joint spatial anchor and negative with more heterogeneous habitat distribution, appearing to favor predators when resources are patchy and limited. However, the site with a joint spatial anchor experienced lower per capita kill rates, greater spatial predictability of kills, and reduced preferred hunting area, appearing to instead favor prey. Therefore, neither of our hypotheses were fully supported, as both behavioral and lethal predation effects were weaker when a spatial anchor was shared by predator and prey. Despite lower spatial overlap, pumas were more efficient hunters in the absence of a joint spatial anchor. Our work indicates that predators do not have to win the spatial response race to achieve comparatively high rates of exploitation, and that predator-prey spatial overlap may not best represent risk for prey species threatened by ambush predators that hunt infrequently.