EVOLUTIONARILY STABLE STEALING - GAME-THEORY APPLIED TO KLEPTOPARASITISM

We present an individual-based model of a group of foraging animals.In dividuals can obtain food either by discovering it themselves or by st ealing it from others (kleptoparasitism). Given that challenging anoth er individual for a discovered food item costs time (which could other wise be spent searching for an undiscovered item), attempting to steal from another may not always be efficient. We show that there is gener ally a unique strategy that maximizes uptake rate-always or never chal lenging others. For any combination of parameter values, we can identi fy which strategy is appropraite. As a corollary to this, we predict t hat small changes in ecological conditions can, under some circumstanc es, cause a dramatic change in the aggressive behavior of individuals. Further, we investigate situations where searching for undiscovered f ood and searching for potential opportunities for stealing are mutuall y exclusive activities (i.e., success at one can only be improved at t he expense of the other). Using game theory, we are able to find the e volutionarily stable strategy for investment in these two activities i n terms of the ecological parameters of the model.