Lucas 9222313 An important focus in the study of the functional significance of behavior has been the impact of physiological state on the expression of foraging decisions. In the past, experimenters have imposed changes in hunger and mass on an animal and have monitored the resulting changes in behavior. However, behavioral systems involve a feedback loop, because foraging decisions themselves will influence further changes in physiological state. Dr. Lucas's research will be one of the first attempts to evaluate the entire feedback loop for a caching animal. Food-caching behavior has often been seen as one mechanism that permits small animals to live through energetically stressful periods, notably winter. Dr. Lucas has found that certain conditions actually retard the storage of food by chickadees, and this in turn reduced the ability of these birds to maintain sufficient body mass to survive when food was scarce. The current reseearch is designed to study conditions that affect the storage of energy, both in the form of body mass and food stores. Energy-storage tactics will in turn affect the ability of birds faced with resource shortfall to alter their behavior in order to improve their chances of survival. Because Dr. Lucas will be studying regulation of body mass as well as food hoards, his results will be broadly applicable to understanding regulation of energy and body mass in any species, including humans.