International Journal of Primatology

, Volume 8, Issue 6, pp 635–650

Rank and density correlates of inclusive fitness measures in a natural chacma baboon (Papio ursinus) troop

  • John Bulger
  • William J. Hamilton

DOI: 10.1007/BF02735781

Cite this article as:
Bulger, J. & Hamilton, W.J. Int J Primatol (1987) 8: 635. doi:10.1007/BF02735781


Some demographic characteristics of a group of chacma baboons (Papio ursinus)in a natural environment in northern Botswana were monitored for an 8-year interval. The group size ranged from 73 to 43 individuals. After 3 years at a high density, the group size declined over a 2-year interval, then stabilized again at reduced numbers (−41 %) and biomass (−40%) for over 2 years. The reduction in group size and biomass was followed by an increase in fecundity, greater for high-ranking than for low-ranking females. At the larger group size, survival was lower for infants born to low-ranking than to high-ranking females. Infant survival rates by female rank were equal at the lower density. The mean weight of adult females increased as the density decreased, but there was no correlation between female rank and body mass. We conclude that there is a negative relationship of density to individual condition and reproductive success and that there are fitness advantages to high female rank.

Key words

baboonfield studyfecunditygroup sizeinfant survival

Copyright information

© Plenum Publishing Corporation 1987

Authors and Affiliations

  • John Bulger
    • 1
  • William J. Hamilton
    • 1
  1. 1.Division of Environmental StudiesUniversity of CaliforniaDavis, Davis
  2. 2.Maun