65.3  Saturday, Jan. 5  Anticipatory Stress, Territoriality and Hunting in Wild Chimpanzees SOBOLEWSKI, ME*; BROWN, JL; MITANI, JC; University of Michigan mesobole@umich.edu

Territoriality and hunting are energetically and psychologically demanding aspects of male chimpanzee behavior. The stress response allows an individual to quickly alter its physiological and behavioral profile to successfully navigate such behaviors. The discrete nature of these competitions permitted us to investigate any anticipatory urinary hormone variation associated with these behaviors in the Ngogo chimpanzee community, in Kibale National Park, Uganda. Here, we investigated the correlation between cortisol, a stress hormone, territorial and hunting aggression. Our results indicated that territoriality and hunting are facilitated by increases in adrenal activity and cortisol production. More importantly, these data showed that cortisol increases before any aggression transpires. In an earlier study, we found that male chimpanzees display anticipatory increases in testosterone in advance of territorial behavior but not hunting. Therefore, we investigated two correlates of territorial behavior, large male party size and location in territory, in an attempt to identify cues associated with these anticipatory hormone increases. However, neither correlate explained the increases in anticipatory hormone concentrations. Being on the periphery of their territory was not associated with elevated cortisol or testosterone concentrations. Group size was not associated with testosterone variation and cortisol levels, contrary to expectation, were higher when males were in smaller groups. The potential cues that explain the observed anticipatory increases in cortisol are still unknown.