International Journal of Primatology

, Volume 22, Issue 6, pp 947–959

What Factors Affect the Size of Chimpanzee Parties in the Kalinzu Forest, Uganda? Examination of Fruit Abundance and Number of Estrous Females


DOI: 10.1023/A:1012061504420

Cite this article as:
Hashimoto, C., Furuichi, T. & Tashiro, Y. International Journal of Primatology (2001) 22: 947. doi:10.1023/A:1012061504420


We examined factors affecting the size of chimpanzee parties in the Kalinzu Forest, Uganda. We found that the number of individuals in a party increased with observation time. Therefore, we employed two methods to reduce this bias: (1) we evaluated party size via the mean number of individuals observed in each 1-h period during the observation of a party (1-h party size), and (2) we used the number of all individuals observed in a party (1-day party size) and performed an analysis of covariance, with observation time of the party as the covariant. We examined factors that might affect party size: fruit abundance, fruit distribution, and number of estrous females. There was no relationship between party size and fruit abundance or distribution. Conversely, the number of males has a significant positive correlation with the number of estrous females, though there is no correlation with the number of anestrous females. These results suggest that males tended to join parties with more females in estrous, irrespective of differences in fruit availability.

Pan troglodytes party size fruit abundance estrous female Kalinzu Forest 

Copyright information

© Plenum Publishing Corporation 2001

Authors and Affiliations

  • Chie Hashimoto
    • 1
  • Takeshi Furuichi
    • 2
  • Yasuko Tashiro
    • 1
  1. 1.Primate Research InstituteKyoto UniversityInuyama, AichiJapan
  2. 2.Laboratory of BiologyMeiji-Gakuin University, tTotsuka, YokohamaKanagawaJapan