Wild chimpanzees, Pan troglodytes, frequently hunt and share meat. Despite
widespread interest and considerable study, continued controversy exists re
garding the factors that influence chimpanzee hunting decisions and meat sh
aring. Three hypotheses invoke the importance of ecological, reproductive a
nd social factors. A nutritional shortfall hypothesis suggests that chimpan
zees hunt to compensate for seasonal shortages in food availability. A seco
nd hypothesis argues that male chimpanzees hunt to obtain meat that they sw
ap for matings. A third hypothesis proposes that males use meat as a social
-tool to develop and maintain alliances with other males. We tested these h
ypotheses using observations of an unusually large community of chimpanzees
at Ngogo in Kibale National Park, Uganda. Results did not support the nutr
itional shortfall or meat-for-sex hypotheses. The Ngogo chimpanzees hunted
primarily during times of food abundance rather than scarcity. The presence
of oestrous females did not predict the tendency of chimpanzees to hunt. F
urthermore, meat-for-sex exchanges occurred infrequently, and males did not
gain a mating advantage through sharing meat. Additional observations were
consistent with the male social bonding hypothesis. At Ngogo, male chimpan
zees were likely to hunt when accompanied by other males. Males shared meat
nonrandomly and reciprocally among themselves, and males exchanged meat fo
r agonistic support. Although several factors are likely to affect chimpanz
ee hunting decisions and meat sharing, these results indicate that primary
causes will not be found through invoking simple energetic or reproductive
considerations. (C) 2001 The Association for the Study of Animal Behaviour.