Acquisition of foraging competence in wild brown capuchins (Cebus apella), with special reference to conspecifics' foraging artefacts as an indirect social influence

Wild brown capuchins (Cebus apella) in Raleighvallen, Suriname forage on larvae hidden inside bamboo stalks via searching and extractive behaviours. We found that developing proficiency at obtaining larvae from bamboo stalks extends through several years of juvenescence. Older juveniles pass through a transition from a juvenile pattern to an adult pattern of foraging efficiency and diet selection. Whereas most studies have investigated the contribution of direct interactions between a naive individual and a competent forager on the acquisition of foraging expertise, we focused on indirect social influence through foraging artefacts left in the habitat by conspecifics. Young individuals foraged at bamboo stalks more often shortly after than shortly before encountering bamboo segments previously opened by foragers to extract larvae. We discuss this result in terms of stimulus enhancement and social facilitation. In capuchins, learning how to forage on difficult foods does not necessarily occur in the presence of other group members, and social influences can be delayed in time and separate in space from others. This study provides an original view on how the gradual acquisition of foraging competence in brown capuchins is aided jointly by physical maturation and indirect social input that provides opportunities to practice appropriate foraging actions.