Behavioral Ecology and Sociobiology

, Volume 35, Issue 4, pp 261–272

Predation risk and the number of adult males in a primate group: a comparative test

  • Carel P. van Schaik
  • Mark Hörstermann

DOI: 10.1007/BF00170707

Cite this article as:
Schaik, C.P.. & Hörstermann, M. Behav Ecol Sociobiol (1994) 35: 261. doi:10.1007/BF00170707


The number of adult males in a bisexual primate group is thought to be determined mainly by the defensibility of mating access to the females. However, among primates, small groups sometimes contain several adult male. We evaluate the hypothesis that high predation risk may lead to greater male representation in primate groups, independent of the effect of group size. Male primates are known to be more vigilant than females, and may also be better at detecting potential predators. A comparative test was done using arboreal folivores in three continents, howler monkeys in the Neotropics, colobus monkeys in Africa and langurs in South and Southeast Asia. Howlers and colobus are exposed to predation by large monkey-eating eagles, whereas the langurs are not. We conducted regression analyses on group composition data of single populations and on mean group compositions among populations, and found that the arboreal langurs basically live in groups with only a single adult males whereas groups of howler and colobus monkeys of comparable size have multiple adult males (Fig. 3). Thus, the hypothesis was supported. Several alternative hypotheses do not account for this pattern.

Key words

Arboreal folivores Primates Predation Group composition 

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Carel P. van Schaik
    • 1
  • Mark Hörstermann
    • 2
  1. 1.Department of Biological Anthropology and AnatomyDuke UniversityDurhamUSA
  2. 2.Department of ZoologyDuke UniversityDurhamUSA
  3. 3.Theodor-Boveri-Institut fur Biowissenschaften, Zoologie IIIWürzburgGermany

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