PREDATOR AND PREY HABITAT SELECTION GAMES: THE EFFECTS OF HOW PREY BALANCE FORAGING AND PREDATION RISK

Abstract

The spatial distributions of predators and prey can be shaped by both intra-and interspecific games. Most predator-prey studies, however, have ignored the interspecific game by focusing on how either predators or prey distribute themselves while holding the distribution of the other species fixed. We use genetic algorithms to examine how the distributional outcome of the game between predators and prey depends on how prey balance the costs of predation risk and the benefits of foraging success. We construct two prey fitness functions. The first prey fitness function has prey reproducing when they reach a threshold mass, which leads to prey choosing patches by minimizing the ratio of predation and foraging rates (m/f). The second prey fitness function has prey reproducing at the end of a season with mass-dependent reproductive success, which leads to prey choosing patches by maximizing their increase in reproductive value over time. When prey minimize m/f, predator and prey distributions are unaffected by the overall level of predation risk. In contrast, when prey maximize their increase in reproductive value, under conditions with low predation risk the distributions of prey and predators are shaped mainly by prey competition and the distribution of resources, and as the overall level of predation risk increases the distribution of prey is increasingly shaped by the distribution of predators. Thus, the dynamics of how predators and prey distribute themselves and interact may depend on factors that affect the overall level of predation risk, such as per predator capture rates, predator densities, and shelter from predation.