Toward an Experimental Socioecology of Primates

Abstract

Interactions in which one animal takes over a food resource from another (feeding sup-plants) are usually interpreted as evidence of feed-ing competition, and the level of competition is predicted to be proportionate to the value of the resource. However, in this study of juvenile olive baboons (Papio anubis) living in a troop near Gil-gil, Kenya, individuals were less selective about the quality of the supplant food under certain social circumstances. Two major food classes, Grass and Corm, were compared. Corms were less common in the diet, more difficult to locate as a replacement food after a supplant, and then at greater distances than Grass: in general, corms were the favoured supplant food, as predicted. But in interactions be-tween animals who were close in rank, supplants over Grass occurred more often than expected. It is suggested here that, in these particular interac-tions, the winner benefitted socially, even at some cost of time or energy. Further, such interactions which may serve to reinforce the winner's status will be most productively directed to those close in rank, where relationships are potentially less sta-ble. These data provide evidence that baboons can discriminate the relative ranks of others, rather than simply distinguishing between individuals who are higher-or lower-ranking than themselves.