Prey Size Selection under Conditions of Competitive Foraging in Captive Chimpanzees

Abstract

First paragraph: Wild chimpanzees (Pan troglodytes) normally select a food item based on two nutritional cues, size and colour [1, 2]. Often wild chimpanzees forage in small groups of individuals, who may encounter a clumped food resource with many food items being available simultaneously (e.g. berries on a small bush [2]). In this situation, travel time between food items may be equal to zero and differences that exist may only relate to the nutritional quality of the food (e) and differences in handling time (h). Thus, prey selection should occur to maximise the e/h ratio [3], since the assumptions of the classic diet model are the same for sequentially and simultaneously encountered prey, but maximisation of e/h may not be an optimal strategy when food resources are limited and individuals are competing against one another. Barnard and Brown [4] found that under conditions of ‘apparent' food competition previously e/h-maximising common shrews (Sorex araneus L.) adopted an unselective strategy.