Behavioral Ecology and Sociobiology

, Volume 61, Issue 5, pp 661–668

Estrus cycle asynchrony in wild female chimpanzees, Pan troglodytes schweinfurthii


    • Department of Welfare and CultureOkinawa University
  • Miya Hamai
    • Primate Research InstituteKyoto University
  • Hitosige Hayaki
    • The Graduate School of Humanities and SciencesKobe Gakuin University
  • Kazuhiko Hosaka
    • Faculty of Child StudiesKamakura Women’s University
  • Kevin D. Hunt
    • Department of AnthropologyIndiana University
  • Eiiti Kasuya
    • Department of BiologyKyushu University
  • Kenji Kawanaka
    • Department of Biosphere–Geosphere System ScienceOkayama University of Science
  • John C. Mitani
    • Department of AnthropologyUniversity of Michigan
  • Hiroyuki Takasaki
    • Department of Biosphere–Geosphere System ScienceOkayama University of Science
  • Yukio Takahata
    • School of Policy StudiesKwansei Gakuin University
Original Article

DOI: 10.1007/s00265-006-0287-9

Cite this article as:
Matsumoto-Oda, A., Hamai, M., Hayaki, H. et al. Behav Ecol Sociobiol (2007) 61: 661. doi:10.1007/s00265-006-0287-9


Although estrous synchrony has been reported in a number of mammalian species, most often among primates, methodological and analytical problems make it difficult to interpret these results. We developed a novel estrous synchrony index and employed a randomization procedure to analyze long-term observations of female chimpanzee (Pan troglodytes schweinfurthii) estrous cycles at the Mahale Mountains National Park, Tanzania. Our results revealed that female chimpanzees at Mahale avoid synchronizing their estrous periods with each other. We also found that birthrates decreased as the breeding sex ratio increased. We suggest that estrous asynchrony decreases female–female competition for mates. Asynchrony may also reduce the potential for male sexual coercion by nonpreferred mating partners.


Timing of estrusMating strategyFemale competitionSexual conflictChimpanzees

Copyright information

© Springer-Verlag 2007