title: Apes finding ants: Predator-prey dynamics in a chimpanzee habitat in Nigeria.
abstract: Some chimpanzee populations prey upon army ants, usually with stick tools. However, how their prey's subterranean nesting and nomadic lifestyle influence the apes' harvesting success is still poorly understood. This is particularly true for chimpanzees (Pan troglodytes ellioti) at Gashaka/Nigeria, which consume army ants (Dorylus rubellus) with much higher frequency than at other sites. We assessed various harvesting and search options theoretically available to the apes. For this, we reconstructed annual consumption patterns from feces and compared the physical characteristics of exploited ant nests with those that were not targeted. Repeated exploitation of a discovered nest is viable only in the short term, as disturbed colonies soon moved to a new site. Moreover, monitoring previously occupied nest cavities is uneconomical, as ants hardly ever re-used them. Thus, the apes have to detect new nests regularly, although colony density is relatively low (1 colony/1.3 ha). Surprisingly, visual search cues seem to be of limited importance because the probability of a nest being exploited was independent of its conspicuousness (presence of excavated soil piles, concealing leaf-litter or vegetation). However, chimpanzees preferentially targeted nests in forests or at the base of food trees, that is, where the apes spend relatively more time and/or where ant colony density is highest. Taken together, our findings suggest that, instead of employing a search strategy based on visual cues or spatial memory, chimpanzee predation on army ants contains a considerable opportunistic element.
authors.affiliation: Grupo UCM para el Estudio del Comportamiento Animal y Humano, Departamento de Psicobiología, Facultad de Psicología, Universidad Complutense de Madrid, Madrid, Spain; Research Laboratory for Archaeology and the History of Art, University of Oxford, Oxford, United Kingdom; Gashaka Primate Project, PMB 08, Serti, Taraba State, Nigeria.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Pascual-Garrido
authors.forename: Buba
authors.initials: B
authors.lastname: Umaru
authors.forename: Oliver
authors.initials: O
authors.lastname: Allon
authors.forename: Volker
authors.initials: V
authors.lastname: Sommer
mesh_terms: D000818:Animals; D001000:Ants; D017753:Ecosystem; D005247:Feeding Behavior; D009549:Nigeria; D002679:Pan troglodytes / Q000502:physiology*; D011156:Population Density; D011235:Predatory Behavior
keywords: army ants; chimpanzee; insectivory; predation; primate archaeology