Correlates of individual participation in boundary patrols by male chimpanzees

Anthony P. Massaro, Ian C. Gilby, Nisarg Desai, Alexander Weiss, Joseph T. Feldblum, Anne E. Pusey, Michael L. Wilson

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Group territory defence poses a collective action problem: individuals can free-ride, benefiting without paying the costs. Individual heterogeneity has been proposed to solve such problems, as individuals high in reproductive success, rank, fighting ability or motivation may benefit from defending territories even if others free-ride. To test this hypothesis, we analysed 30 years of data from chimpanzees ( Pan troglodytes) in the Kasekela community, Gombe National Park, Tanzania (1978-2007). We examined the extent to which individual participation in patrols varied according to correlates of reproductive success (mating rate, rank, age), fighting ability (hunting), motivation (scores from personality ratings), costs of defecting (the number of adult males in the community) and gregariousness (sighting frequency). By contrast to expectations from collective action theory, males participated in patrols at consistently high rates (mean ± s.d. = 74.5 ± 11.1% of patrols, n = 23 males). The best predictors of patrol participation were sighting frequency, age and hunting participation. Current and former alpha males did not participate at a higher rate than males that never achieved alpha status. These findings suggest that the temptation to free-ride is low, and that a mutualistic mechanism such as group augmentation may better explain individual participation in group territorial behaviour. This article is part of the theme issue 'Intergroup conflict across taxa'.

Original languageEnglish (US)
Article number20210151
JournalPhilosophical Transactions of the Royal Society B: Biological Sciences
Issue number1851
StatePublished - 2022

Bibliographical note

Funding Information:
Agence Nationale de la Recherche (ANR-17-EURE-0010), Arcus Foundation, Arizona State University, Carnegie Corporation of New York, Duke University, Jane Goodall Institute, Leakey Foundation, Leo S. Guthman Foundation, Margo Marsh, National Geographic Society, U.S. Department of Health and Human Services, National Institutes of Health (R00 HD057992, R01 AI050529, R01 AI120810), National Science Foundation (BCS-0452315, BCS-0648481, BCS-1743506, BCS-1753437, DBS-9021946, IOS-1052693, IOS-1457260, SBR-9319909), the Harris Steel Group, University of Minnesota, Wilkie Foundation, William T. Grant Foundation, Windibrow Foundation.

Publisher Copyright:
© 2022 Royal Society Publishing. All rights reserved.


  • Pan troglodytes
  • boundary patrols
  • collection action problems
  • hunting
  • intergroup aggression
  • territorial behaviour
  • Humans
  • Male
  • Personality
  • Reproduction
  • Territoriality
  • Animals
  • Motivation

PubMed: MeSH publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Journal Article
  • Research Support, N.I.H., Extramural


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