The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Diet composition of savanna chimpanzees at Toro-Semliki Wildlife Reserve, Uganda


Anthropology Department, Indiana University Bloomington

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The mosaic of forest, wood- and grassland in dry chimpanzee (Pan troglodytes) habitats has been proposed as a good extant model for hominin paleoenvironments. The habitat of “savanna” chimpanzees is open, seasonally dry and often described as “marginal” because suitable fruits are purportedly scarce and widely distributed. Understanding the diet of savanna chimpanzees is therefore the basis for understanding the evolution of morphological and behavioral niche adaptations in early hominins.

Thus far, the only two detailed studies on savanna chimpanzee feeding ecology are from West Africa. Both sites are proposed to differ from East African sites in their composition of woodland and other habitats used by chimpanzees. This is the first systematic study of chimpanzee diet composition at Toro-Semliki Wildlife Reserve, Uganda. The Mugiri community is the only habituated savanna chimpanzee community experiencing a bimodal rainfall pattern. Over one year (2009-2010), diet composition of this community was assessed through fecal samples (n=311) and observations.

Semliki chimpanzees relied on 1-2 food species in their monthly diet, and most food items were harvested in the gallery forest, rarely from the bush- and grassland. After the unusually short first dry season in 2010, normally preferred species failed to produce an abundant crop. Chimpanzees consumed figs, Phoenix palm fruits and fruits from shrubs (Securinega virosa, Dovyalis macrocalyx). When these were depleted, chimpanzees fed heavily on the cambium/bark of trees and Aframomum fruits. This study supports the notion that savanna chimpanzees must cope with great spatio-temporal variability in food resources.

This study was supported by the National Science Foundation BCS 98-15991, by the Indiana University Foundation and by Indiana University’s Faculty Research Support Program.

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