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Flexible grouping patterns in a western and eastern chimpanzee community.

Published version
Peer-reviewed

Repository DOI


Change log

Authors

Camara, Henry Didier 
Keir, Alex 

Abstract

Primate social organizations, or grouping patterns, vary significantly across species. Behavioral strategies that allow for flexibility in grouping patterns offer a means to reduce the costs of group living. Chimpanzees (Pan troglodytes) have a fission-fusion social system in which temporary subgroups ("parties") change in composition because of local socio-ecological conditions. Notably, western chimpanzees (P. t. verus) are described as showing a higher degree of bisexual bonding and association than eastern chimpanzees, and eastern female chimpanzees (P. t. schweinfurthii) are thought to be more solitary than western female chimpanzees. However, reported comparisons in sociality currently depend on a small number of study groups, particularly in western chimpanzees, and variation in methods. The inclusion of additional communities and direct comparison using the same methods are essential to assess whether reported subspecies differences in sociality hold in this behaviorally heterogeneous species. We explored whether sociality differs between two communities of chimpanzees using the same motion-triggered camera technology and definitions of social measures. We compare party size and composition (party type, sex ratio) between the western Gahtoy community in the Nimba Mountains (Guinea) and the eastern Waibira community in the Budongo Forest (Uganda). Once potential competition for resources such as food and mating opportunities were controlled for, subspecies did not substantially influence the number of individuals in a party. We found a higher sex-ratio, indicating more males in a party, in Waibira; this pattern was driven by a greater likelihood in Gahtoy to be in all-female parties. This finding is the opposite of what was expected for eastern chimpanzees, where female-only parties are predicted to be more common. Our results highlight the flexibility in chimpanzee sociality, and caution against subspecies level generalizations.

Description

Publication status: Published


Funder: Newnham College, University of Cambridge; doi: http://dx.doi.org/10.13039/501100000663


Funder: Royal Zoological Society of Scotland; doi: http://dx.doi.org/10.13039/100014969


Funder: Homerton College, University of Cambridge; doi: http://dx.doi.org/10.13039/501100008420


Funder: Gates Cambridge Trust; doi: http://dx.doi.org/10.13039/501100005370


Funder: Stichting Lucie Burgers; doi: http://dx.doi.org/10.13039/501100013496

Keywords

camera trapping, chimpanzee, party composition, party size, sociality, Male, Female, Animals, Pan troglodytes, Hominidae, Social Behavior, Uganda, Forests

Journal Title

Am J Primatol

Conference Name

Journal ISSN

0275-2565
1098-2345

Volume Title

Publisher

Wiley
Sponsorship
Ministry of Education, Culture, Sports, Science and Technology (#12002009, #16002001, #20002001, #24000001, #16H06)
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (PCEFP3_186967)