The consequences of predators without prey

Abstract

Rapid and ongoing environmental change is leading to scenarios where marine and terrestrial predators are persisting without prey, either by scavenging or using anthropogenic foods. Despite investigations into the effects of predator presence or absence on prey behavior and ecology, little research has assessed the effect of prey absence on predators. Here, we synthesize research on scavenging and the use of anthropogenic resources by marine and terrestrial predators; hypothesize how the use of these resources may change predator behavior with respect to their social structure, space use, life history, and individual behavioral traits; and illustrate how these changes are likely to have cascading effects through ecosystems. The prevalence of predators persisting without prey will almost certainly change in the future due to altered availability of anthropogenic foods, scavenging opportunities, and natural prey. We discuss areas of needed research and the relevance of our findings to both the conservation and ecology of predators and management of human–wildlife conflict.