Organisms make a variety of decisions while foraging, each with different costs and benefits. For example, predator foraging behaviors fall within a spectrum that ranges from hunting to scavenging. In this study, we examine the behavior of a group of consumers that can actively hunt for prey, or scavenge from the foils of a fixed pool of predators, either by consuming leftovers (passive scavenging) or by stealing from a victim (active scavenging, or kleptoparasitism). We then examine whether and to what extent these behaviors are driven by body size limitations with respect to both the predator and potential prey. We employ a stochastic dynamic programming model to construct a deterministic matrix of fitness-maximizing foraging behavior as a function of the consumer’s energetic state. We generalize our foraging model in terms of organismal body mass so that we can explore multiple and specific predator-prey interactions observed in the wild, thereby determining the relationship between body-size classes and different predatory behaviors, as well as to better understand trade-offs in decision-making associated with body-size limitations.
Results/Conclusions
Our results suggest that predator foraging strategy is the result of a non-trivial interplay of predator, prey, and victim size. Hunting and passive scavenging are the dominant behavioral choices across predator body size while risky behavior (active scavenging) is only viable for a much smaller range of predator body sizes. For instance, hunting is favored by large predators, regardless of the size of prey or victim. Smaller predators, however, resort to passive scavenging when the prey is large. Passive scavenging is also the preferred strategy for smaller predators when the victim is large, presumably because of the high risk associated with stealing from a large victim. However, when the victim is small, smaller predators will engage in active scavenging. In general, larger predators rely on hunting nearly exclusively, while smaller predators engage in both passive and active scavenging, pointing to the existence of some body size limitation on foraging strategies. Thus, our study provides insights into how predators adopt fitness maximizing foraging strategies by mitigating risk, and how these strategies change across combinations of predator, prey and victim body size.