The Influence of Ecology on Chimpanzee (Pan troglodytes) Cultural Behavior: A Case Study of Five Ugandan Chimpanzee Communities Thibaud Gruber University of St. Andrews and Budongo Conservation Field Station, Masindi, Uganda Kevin B. Potts Augsburg College Christopher Krupenye Connecticut College and Duke University Maisie-Rose Byrne, Constance Mackworth-Young, and William C. McGrew University of Cambridge Vernon Reynolds Budongo Conservation Field Station, Masindi, Uganda and Oxford University Klaus Zuberbu ¨hler University of St. Andrews and Budongo Conservation Field Station, Masindi, Uganda The influence of ecology on the development of behavioral traditions in animals is controversial, particularly for chimpanzees (Pan troglodytes), for which it is difficult to rule out environmental influences as a cause of widely observed community-specific behavioral differences. Here, we investigated 3 potential scenarios that could explain the natural variation in a key extractive tool behavior, “fluid-dip,” among several communities of chimpanzees of the Pan troglodytes schweinfurthii subspecies in Uganda. We compared data from previous behavioral ecological studies, field experiments, and long-term records of chimpanzee tool-using behavior. We focused on the quality of the available food, dietary preferences, and tool sets of 5 different communities, and carried out a standardized field experiment to test systematically for the presence of fluid-dip in 4 of these communities. Our results revealed major differences in habitat, available diet, and tool use behavior between geographically close communities. However, these differences in ecology and feeding behavior failed to explain the differences in tool use across communities. We conclude that ecological variables may lead both to innovation and loss of behavioral traditions, while contributing little to their transmission within the community. Instead, as soon as a behavioral tradition is established, sociocognitive factors likely play a key maintenance role as long as the ecological conditions do not change sufficiently for the tradition to be abandoned. Keywords: ecology, tool use, Pan troglodytes schweinfurthii, culture Chimpanzees are some of the most accomplished tool users in the animal kingdom, a finding that has considerable implications for understanding the evolutionary origins of human cognition and capacity for culture. However, it is also well established that wild chimpanzee communities vary in their use of tools and, notably, that some communities hardly show any tool use (McGrew, 1992, 2010; Whiten et al., 1999). An ongoing source of contention concerns the nature of the mechanisms that have led to the ob- Thibaud Gruber and Klaus Zuberbu ¨hler, School of Psychology, Univer- sity of St. Andrews, St. Andrews, Scotland; Budongo Conservation Field Station, Masindi, Masindi District, Uganda; Kevin B. Potts, Department of Biology, Augsburg College; Christopher Krupenye, Department of Biol- ogy, Connecticut College; Department of Evolutionary Anthropology, Duke University; Maisie-Rose Byrne and Constance Mackworth-Young, Jesus College, University of Cambridge, Cambridge, England; William C. McGrew, Department of Archaeology and Anthropology, University of Cambridge, Cambridge, England; Vernon Reynolds, Budongo Conserva- tion Field Station, Masindi, Masindi District, Uganda; Magdalen College, Oxford University, Oxford, England. Permissions for this project were given by the Uganda Wildlife Author- ity, the Ugandan National Council for Science and Technology, and the National Forestry Authority. Ethical approval was given by the School of Psychology, University of St. Andrews. The study was funded by the Leverhulme Trust (U.K.). Additional support was by the Wissenschafts- kolleg zu Berlin. Christopher Krupenye was supported by National Science Foundation Graduate Research Fellowship Grant DGE-1106401. We are grateful to the Royal Zoological Society of Scotland for providing core funding for the Budongo Conservation Field Station (BCFS). We thank Fred Babweteera and Zephyr Kiwede at BCFS and Amos Wekesa, Baylon Iga, and Doreen Kafureka at Great Lake Safaris for their support. For assistance in the field, we thank Stephen Amati at Sonso, James Kyo- muhendo and Emily Otali at Kanyawara, Nyoli and Butele Lino at Kaniyo Pabidi, and Vincent Odama and Chombe Deo at Busingiro. We thank Tony Goldberg and Fred Babweteera for their expert advice on the evolutionary history of African forests. We thank the editor and the reviewers for their valuable comments. Correspondence concerning this article should be addressed to Thibaud Gruber, School of Psychology, University of St. Andrews, South Street, St. Andrews, KY169JP, United Kingdom. E-mail: tg227@st-andrews.ac.uk Published in Journal of Comparative Psychology, Vol. 126, Issue 4, 2012, p. 446-457 which should be used for any reference to this work 1