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


Patterns of ant-fishing for carpenter ants (Camponotus spp.) by Gombe and Mahale chimpanzees

ROBERT C. O'MALLEY1 and HITONARU NISHIE2.

1Anthropology, Kenyon College, 2Wildlife Research Center, Kyoto University

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Cross-site comparisons of termite-fishing (for Macrotermes) and ant-dipping (for Dorylus) suggest that both cultural traditions and microecological factors influence tool-assisted insectivory by chimpanzees. Predation on Camponotus ants with tools (or “ant-fishing”) is reported at fewer long-term sites than other insectivory patterns. Here we compare patterns of predation on Camponotus at two sites and four communities- Mahale (K- and M-group) and Gombe (Kasekela and Mitumba).

Ant-fishing was identified as 'customary' in K- and M-group and 'habitual' in Mitumba soon after habituation on each began. In contrast, ant-fishing was conclusively documented in Kasekela only in 1994, after decades of prior observation. Circumstantial evidence suggests that a Mitumba immigrant introduced ant-fishing to Kasekela in 1992.

Ant-fishing was 'customary' in Kasekela by 2010. Nevertheless, Kasekela chimpanzees fished for fewer species of Camponotus than the other three communities, though the same prey species were available. Ant-fishing occured at a lower frequency, for shorter durations, in fewer tree species, and at fewer locations in Kasekela than in Mahale. Ant-fishing was observed by all non-infant members of M-group and most adult males and females in Mitumba. In Kasekela ant-fishing was observed almost exclusively by younger cohorts and immigrant females, and was never observed among adult males.

This cross-site comparison is consistent with O’Malley et al.’s (2012) conclusion that ant-fishing in Kasekela is a recent cultural phenomenon, though also suggests that differences in ant-fishing behavior even in neighboring communities are influenced by local environmental conditions (e.g., the abundance and distribution of Camponotus-infested trees), consistent with prior studies.

Robert O’Malley’s research was supported by a USC Joint Initiative Merit Fellowship, a USC Gold Family Fellowship, a USC International Summer Field Research Award, and the USC Jane Goodall Center. Hitonaru Nishie was supported by a MEXT Grant-in-Aid for Scientific Research (#16255007 to T. Nishida and #19107007 to J. Yamagiwa), and a Grant-in-Aid for 21st Century COE Research (A14).

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