title: Wild chimpanzees plan their breakfast time, type, and location.
abstract: Not all tropical fruits are equally desired by rainforest foragers and some fruit trees get depleted more quickly and carry fruit for shorter periods than others. We investigated whether a ripe-fruit specialist, the chimpanzee (Pan troglodytes verus), arrived earlier at breakfast sites with very ephemeral and highly sought-after fruit, like figs, than sites with less ephemeral fruit that can be more predictably obtained throughout the entire day. We recorded when and where five adult female chimpanzees spent the night and acquired food for a total of 275 full days during three fruit-scarce periods in a West African tropical rainforest. We found that chimpanzees left their sleeping nests earlier (often before sunrise when the forest is still dark) when breakfasting on very ephemeral fruits, especially when they were farther away. Moreover, the females positioned their sleeping nests more in the direction of the next day's breakfast sites with ephemeral fruit compared with breakfast sites with other fruit. By analyzing departure times and nest positioning as a function of fruit type and location, while controlling for more parsimonious explanations, such as temperature, we found evidence that wild chimpanzees flexibly plan their breakfast time, type, and location after weighing multiple disparate pieces of information. Our study reveals a cognitive mechanism by which large-brained primates can buffer the effects of seasonal declines in food availability and increased interspecific competition to facilitate first access to nutritious food. We discuss the implications for theories on hominoid brain-size evolution.
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany; karline_janmaat@eva.mpg.de.
authors.forename: Karline R L
authors.initials: KR
authors.lastname: Janmaat
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany; Department of Anthropology, University of California, Davis, CA 95616; and.
authors.forename: Leo
authors.initials: L
authors.lastname: Polansky
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany; Department of Biosciences, Université Félix Houphouët Boigny, Abidjan 22, Ivory Coast.
authors.forename: Simone Dagui
authors.initials: SD
authors.lastname: Ban
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany;
authors.forename: Christophe
authors.initials: C
authors.lastname: Boesch
mesh_terms: D000818:Animals; D059031:Anticipation, Psychological / Q000502:physiology; D005075:Biological Evolution; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology; D007560:Cote d'Ivoire; D005247:Feeding Behavior; D005260:Female; D030681:Ficus; D005518:Food Preferences; D005523:Food Supply; D005638:Fruit; D009425:Nesting Behavior / Q000502:physiology; D009929:Organ Size; D002679:Pan troglodytes / Q000523:psychology*; D013997:Time Factors
keywords: ecological intelligence; flexible planning; foraging strategies; interspecific competition; prospective cognition