Food Competition Among Individuals in a Free-Ranging Chimpanzee Community in Kibale Forest, Uganda

Abstract Competition for fruit within chimpanzee foraging parties was investigated by testing the hypotheses that food patch size was a limiting factor to foraging party size and to foraging efficiency while chimpanzees were foraging in Pseudospondias microcarpa trees for fruit. Large food patches (as measured by phenological score or the product of diameter at breast height and phenological score) supported significantly larger parties than did smaller food patches. In addition, foraging efficiency was apparently higher for small parties than for large ones, although the difference was marginally statistically significant. Per-capita feeding time for individuals in small parties was significantly higher than for those in large parties when chimpanzees had access to both Pseudospondias and Uvariopsis congensis fruit trees. Per-capita feeding time was not significantly correlated with food patch size. When Uvariopsis fruit trees became exhausted in mid-August, some chimpanzees apparently avoided severe competition for fruit by leaving the C.C. area, where they had been feeding on both Uvariopsis and Pseudospondias fruit. Social factors did not significantly affect foraging party size nor per-capita feeding time.