current ecological theory suggests that foraging animals are controlled by the distribution and abundance of food resources. contemporary ecological research focuses on optimizing resources through the maximization of cost-benefit trade-offs. operant psychological research suggests an alternative, but not mutually exclusive approach. dispersion patterns, foraging processes, and animal distribution, are the products of naturally occurring contingencies of reinforcement. the purpose of the present study was to determine whether population patterns could be controlled and explained by operant procedures and principles. the study was designed to examine the effects of an ascending series of variable ratio schedules on the dispersion patterns of a colony of 8 male hooded rats in an environment in which the resources were patchily distributed.