Social foraging and the finder's share in capuchin monkeys, Cebus apella

Group living can confer advantages to individuals, but it can also impose severe costs through resource competition. Kleptoparasitism is one example in which some individuals (joiners) can exploit the food discovered by other animals (finders). This type of social foraging has been modelled either as an information-sharing model or as a producer-scrounger game. An important variable in these models is the finder's advantage: the number of items obtained by the finder before the arrival of other individuals. In this study we describe how the spatial position and rank of individuals in a group of wild tufted capuchin monkeys affect their ability to discover and exploit new food sources. We also analyse the factors that affect the finder's share and the total amount of food obtained by the finder from a newly discovered resource. By placing platforms filled with bananas at novel locations in their home range, we show that animals in the leading edge of a foraging group have a higher probability of discovering new food sources than animals occupying other spatial positions. The alpha male and the alpha female, which tended to occupy central-forward positions, were able to monopolize newly discovered food sources and thus obtain a major share of them. The finder's share at the feeding platforms was smaller when there was more food on a platform, but increased with longer delays before the arrival of other individuals. The total amount of food obtained by the finder from the feeding platforms was larger when there was more food on the platform, when the finder was of higher social status, and when it took longer for other individuals to arrive. Animals can increase their finder's share and total amount consumed from a newly discovered resource by keeping large interindividual distances and by avoiding giving cues about the presence of food (such as food-associated vocalizations) to other animals. (C) 2001 The Association for the Study of Animal Behaviour.