Chimpanzees prey on army ants with specialized tool set

Authors

  • Crickette M. Sanz,

    Corresponding author
    1. Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
    2. Department of Anthropology, Washington University, Saint Louis, Missouri
    • Department of Anthropology, Washington University, 1 Brookings Drive, Saint Louis, MO 63130
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  • Caspar Schöning,

    1. Department of Biology, Centre of Social Evolution, University of Copenhagen, Copenhagen, Denmark
    2. Honey Bee Research Institute, Friedrich-Engels-Strasse, Hohen Neuendorf, Germany
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  • David B. Morgan

    1. Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, Illinois
    2. Wildlife Conservation Society, Congo Program, Brazzaville, Republic of Congo
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Abstract

Several populations of chimpanzees have been reported to prey upon Dorylus army ants. The most common tool-using technique to gather these ants is with “dipping” probes, which vary in length with regard to aggressiveness and lifestyle of the prey species. We report the use of a tool set in army ant predation by chimpanzees in the Goualougo Triangle, Republic of Congo. We recovered 1,060 tools used in this context and collected 25 video recordings of chimpanzee tool-using behavior at ant nests. Two different types of tools were distinguished based on their form and function. The chimpanzees use a woody sapling to perforate the ant nest, and then a herb stem as a dipping tool to harvest the ants. All of the species of ants preyed upon in Goualougo are present and consumed by chimpanzees at other sites, but there are no other reports of such a regular or widespread use of more than one type of tool to prey upon Dorylus ants. Furthermore, this tool set differs from other types of tool combinations used by chimpanzees at this site for preying upon termites or gathering honey. Therefore, we conclude that these chimpanzees have developed a specialized method for preying upon army ants, which involves the use of an additional tool for opening nests. Further research is needed to determine which specific ecological and social factors may have shaped the emergence and maintenance of this technology. Am. J. Primatol. 72:17–24, 2010. © 2009 Wiley-Liss, Inc.

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