, Volume 55, Issue 4, pp 489–499 | Cite as

Variance in the reproductive success of dominant male mountain gorillas

  • Andrew M. Robbins
  • Maryke Gray
  • Prosper Uwingeli
  • Innocent Mburanumwe
  • Edwin Kagoda
  • Martha M. RobbinsEmail author
Original Article


Using 30 years of demographic data from 15 groups, this study estimates how harem size, female fertility, and offspring survival may contribute to variance in the siring rates of dominant male mountain gorillas throughout the Virunga Volcano Region. As predicted for polygynous species, differences in harem size were the greatest source of variance in the siring rate, whereas differences in female fertility and offspring survival were relatively minor. Harem size was positively correlated with offspring survival, even after removing all known and suspected cases of infanticide, so the correlation does not seem to reflect differences in the ability of males to protect their offspring. Harem size was not significantly correlated with female fertility, which is consistent with the hypothesis that mountain gorillas have minimal feeding competition. Harem size, offspring survival, and siring rates were not significantly correlated with the proportion of dominant tenures that occurred in multimale groups versus one-male groups; even though infanticide is less likely when those tenures end in multimale groups than one-male groups. In contrast with the relatively small contribution of offspring survival to variance in the siring rates of this study, offspring survival is a major source of variance in the male reproductive success of western gorillas, which have greater predation risks and significantly higher rates of infanticide. If differences in offspring protection are less important among male mountain gorillas than western gorillas, then the relative importance of other factors may be greater for mountain gorillas. Thus, our study illustrates how variance in male reproductive success and its components can differ between closely related species.


Brown partitions Harem size Infanticide Intra-sexual competition Male quality Mate choice Mating success Offspring survival Sexual selection 



We thank the governments of Rwanda, Democratic Republic of Congo, and Uganda for their steadfast commitment to conserving the mountain gorillas and their transboundary collaboration. We are greatly indebted to the local rangers, guides, field assistants, and staff who have worked tirelessly to protect the gorillas as well as collect the data used in this study. These men and women have shown extraordinary commitment to work during dangerous times, and approximately 100 staff members have been killed while working to protect the gorillas. The International Gorilla Conservation Programme (IGCP), a consortium of the African Wildlife Foundation, Fauna and Flora International, and the World Wide Fund for Nature, thanks all of their contributors to the Ranger Based Monitoring program. We thank Ed Wright, Juichi Yamagiwa, and anonymous reviewers for their helpful comments about the manuscript. We thank Thomas Breuer for permission to include unpublished details from (Breuer et al. 2010). The Max Planck Society provided support for data analysis and write-up of the project.


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Copyright information

© Japan Monkey Centre and Springer Japan 2014

Authors and Affiliations

  • Andrew M. Robbins
    • 1
  • Maryke Gray
    • 2
  • Prosper Uwingeli
    • 3
  • Innocent Mburanumwe
    • 4
  • Edwin Kagoda
    • 5
  • Martha M. Robbins
    • 1
    Email author
  1. 1.Max Planck Institute for Evolutionary AnthropologyLeipzigGermany
  2. 2.International Gorilla Conservation ProgramNairobiKenya
  3. 3.Rwanda Development BoardParc National des VolcansKigaliRwanda
  4. 4.Institut Congolais pour la Conservation de la NatureParc National des Virunga-sudGisenyiRwanda
  5. 5.Mgahinga Gorilla National Park, Uganda Wildlife AuthorityKampalaUganda

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