The Fitness Trade-offs of Predation: When to Scavenge and When to Steal

Predator foraging behavior can fall on a continuous spectrum between hunting and scavenging. Here, we study the behavior of a group of foragers that can actively hunt for prey, or scavenge from the foils of a fixed pool of predators either by eating leftovers (passive scavenging) or by stealing from a predator (active scavenging). To do this, we employ stochastic dynamic programming which enables us to construct a deterministic matrix of decisions and associated fitness values for a set of potential behaviors. This approach is centred around finding consumer behaviors that maximize fitness. Our results suggest that there are well-defined parameter regimes where each foraging strategy maximizes fitness, and that risky behaviour (active scavenging) becomes a viable choice for a small range of parameters when costs associated with hunting and scavenging are comparable or when the mortality associated with active scavenging is low. We then generalise this model in terms of organismal body mass so that it can be applied to real-life systems to determine the relationship between body-size classes and different predatory behaviors, and to better understand trade-offs in decision-making associated with body-size limitations.