Behavioral Ecology and Sociobiology

, Volume 69, Issue 6, pp 1039–1052 | Cite as

Trading or coercion? Variation in male mating strategies between two communities of East African chimpanzees

  • Stefano S. K. KaburuEmail author
  • Nicholas E. Newton-Fisher
Original Paper


Across taxa, males employ a variety of mating strategies, including sexual coercion and the provision, or trading, of resources. Biological market theory (BMT) predicts that trading of commodities for mating opportunities should exist only when males cannot monopolize access to females and/or obtain mating by force, in situations where power differentials between males are low; both coercion and trading have been reported for chimpanzees (Pan troglodytes). Here, we investigate whether the choice of strategy depends on the variation in male power differentials, using data from two wild communities of East African chimpanzees (Pan troglodytes schweinfurthii): the structurally despotic Sonso community (Budongo, Uganda) and the structurally egalitarian M-group (Mahale, Tanzania). We found evidence of sexual coercion by male Sonso chimpanzees, and of trading—of grooming for mating—by M-group males; females traded sex for neither meat nor protection from male aggression. Our results suggest that the despotism–egalitarian axis influences strategy choice: male chimpanzees appear to pursue sexual coercion when power differentials are large and trading when power differentials are small and coercion consequently ineffective. Our findings demonstrate that trading and coercive strategies are not restricted to particular chimpanzee subspecies; instead, their occurrence is consistent with BMT predictions. Our study raises interesting, and as yet unanswered, questions regarding female chimpanzees’ willingness to trade sex for grooming, if doing so represents a compromise to their fundamentally promiscuous mating strategy. It highlights the importance of within-species cross-group comparisons and the need for further study of the relationship between mating strategy and dominance steepness.


Pan troglodytes Mating strategy Social grooming Aggression Dominance rank Biological market theory 



This work was funded by the Wenner-Gren foundation (grant no. 8216), the Leverhulme Trust (grant no. F/00236/Z) and the H.F. Guggenheim Foundation. We thank the Uganda National Council for Science and Technology, the President’s Office, the Forest Department, and Vernon Reynolds for granting permission to work in the Budongo forest and the Tanzania Commission for Science and Technology, the Tanzania Wildlife Research Institute and the Mahale Mountains Wildlife Research Centre for allowing research in the Mahale Mountains National Park. We are also very grateful to Geresomu Muhumuza and the other Ugandan and Tanzanian field assistants for their fundamental help during data collection both in Budongo and Mahale. Finally, we would like to thank Robin Dunbar and two anonymous reviewers for insightful comments on a previous draft of the article.

Ethical standards

This research complied with the regulations set by the Ethics Committee of University of Kent, the protocols of both the Budongo Forest Project (now BCFS) and the Mahale Mountains Wildlife Research Center, and the legal requirements of both Uganda and Tanzania.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Stefano S. K. Kaburu
    • 1
    • 2
    Email author
  • Nicholas E. Newton-Fisher
    • 3
  1. 1.Dipartimento di NeuroscienzeUniversità di ParmaParmaItaly
  2. 2.Laboratory of Comparative EthologyEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentPoolesvilleUSA
  3. 3.School of Anthropology and Conservation, Marlowe BuildingUniversity of KentCanterburyUK

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