Hierarchical predation: wolf (Canis lupus) selection along hunt paths and at kill sites

Predation is a hierarchical process whereby a predator is constrained to killing prey within the area they select while hunting. We demonstrate the hierarchical nature of predation using movement data from six GPS-collared wolves (Canis lupus L., 1758) in the Rocky Mountains of Alberta, Canada, by coupling the kill locations of their ungulate prey with their preceding hunt path. Selection of where to hunt constrained the characteristics influencing where wolves killed within hunt paths. Specifically, wolves selected to hunt where prey densities were higher than the mean density for their territories, but prey densities were not related to kill site locations within the selected hunt path. Wolves selected to hunt in open valleys and near habitat edges, where prey may be most predictable, detectable, or vulnerable, which may have been reinforced by a higher likelihood of killing within these characteristics along hunt paths. In contrast, wolves selected to hunt relatively farther from frozen water bodies and closer to well sites than kill site locations, indicating different processes were occurring during the hunting and killing phases. Treating predation as a hierarchical sequence will ensure the role of prey and landscape characteristics on the processes of predation are not over- or under-emphasized by decoupling kill sites from hunt paths, which will lead to a better mechanistic understanding of predation in heterogeneous environments.