Foraging organisms typically must consider many factors when making decisions about how and when to move within and between patches of food. The objectives of this research are to (1) contrast the responses of two streams insects which are morphologically and behaviorally distinct to combinations of costs and risks experienced while foraging, (2) examine in detail how one potential cost, the presence of competitors, influences foraging behavior, and (3) determine the influence of forager density and resource levels on growth and reproduction. Behavioral observations of responses to forced contacts with competitors and predators under different environmental conditions will be used to compare the relative importance of the different factors. Behavioral observations of interactions between feeding individuals at different densities and resource levels will be used to determine the nature of interactions between potential competitors. Experiments which measure growth rate and fecundity will determine if resource levels and the presence of competitors influence fitness. The principle contribution of this research will be an assessment of interactions between multiple concurrent costs and risks faced while foraging, and a determination of the role of competition. Potential applications of the findings include: management of trout in stocked streams, and prediction of effects of alterations of stream habitats. Basic information from the study will also contribute to the understanding of mechanisms that maintain species diversity and increase the robustness of conservation practices.
