Optimal marauding in bowerbirds

In bowerbirds, males display at bowers but also attempt to destroy the bowers and steal decorations of other males. We develop a game theoretic model to examine optimal marauding behavior in male bowerbirds under the assumption that males have limited amounts of time away from their bower. We model interactions among neighboring males as a stochastic Markovian process and calculate fitness of males as it relates to the amount of time spent marauding. The results are that there are 2 possible evolutionary stable strategy (ESS) profiles: If bower repair time is short (relative to foraging), males should not maraud at all; in contrast, if bower repair time is long, males should maraud at the maximal level. We extend the model in 2 ways: First, allowing for variation in the males’ likelihood of mating, the ESS changes when bower repair time is short. The male mostly likely to mate does not maraud at all, whereas his rival marauds at the maximal level. Second, allowing for variation in males’ abilities to repair their bower, the ESS for the male that can repair his bower quickly is always to maraud, whereas the ESS for the other male (the male who takes longer to repair his bower) is never to maraud but instead to guard his bower. These results suggest that bower marauding may be a dynamic interaction between males, one that varies with ecological factors, and also that interactions may differ between different sets of males.