Temporal Variation in Insect-eating by Chimpanzees and Gorillas in Southeast Cameroon: Extension of Niche Differentiation |
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Authors: | Isra Deblauwe |
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Institution: | (1) Centre for Research and Conservation, Royal Zoological Society of Antwerp, 2018 Antwerp, Belgium;(2) Department of Biology, University of Antwerp, 2610 Wilrijk, Belgium |
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Abstract: | I studied insect-foraging strategies of great apes and aimed to define niche differentiation in their insect diet. I investigated
seasonality in fruit-, foliage-, insect-, and meat-eating by great apes in southeast Cameroon via indirect methods and measured
activity and nest densities of insect prey. I used a multinomial logistic regression to analyze the data. Gorilla and chimpanzee
insect-, ant-, and termite-eating does not correlate with rainfall. Ant- and nonwinged termite-eating by chimpanzees increased
in periods of succulent fruit scarcity and provided protein and energy, which might have compensated for the protein-low foliage
eaten then. The apes ate winged termites when succulent fruit was abundant. Ant and winged termite consumption by gorillas
correlates positively with that of chimpanzees. Ant-eating by gorillas increased when fruit was scarce, but was also associated
with temporal ant activity and nest density. Both ape species also encountered more ant nests and trails in that period, as
they predominantly foraged for herbs in vegetation types with high ant availability. In contrast, fruit-eating correlates
positively with nonwinged termite-eating by gorillas, but again temporal prey availability is also associated. Termites might
have provided 1) supplemental iron when tannin-rich fruits were eaten or 2) antidiarrheal properties when gorillas ate too
much laxative fruit. Termite-eating by both ape species is not associated with spatial termite availability. In conclusion,
there is niche differentiation in their insect diet. Based on the trade-off between foraging effort and nutritional gain,
chimpanzees use a high-energy and gorillas a low-energy strategy when feeding on termites, but both use a low-energy strategy
when feeding on ants. However, more information on the consumption of ant larvae is necessary to define niche differentiation
in their ant diet. |
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Keywords: | ants foraging strategies great apes seasonality termites |
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