Abstract

The costs of foraging can be high while also carrying significant risks. To mitigate these risks, many predators supplement active hunting with scavenging and kleptoparasitism, in some cases specializing in these alternative modes of predation. However, the factors that drive differential utilization of these strategies are not well understood. Here we use an energetics approach to investigate the fitness advantages of hunting, scavenging, and kleptoparasitism as a function of predator, prey, and competitor body sizes for terrestrial mammalian carnivores. Our results reveal that predator strategies become more diverse with declining body condition, while the deployment of scavenging and kleptoparasitism is strongly constrained by the ratio of predator to prey body size. Our model accurately predicts a behavioral transition away from hunting towards alternative modes of predation with increasing prey size for predators spanning an order of magnitude in body size, closely matching observational data across a range of species.