International Journal of Primatology

, Volume 33, Issue 1, pp 134–149 | Cite as

Assessing Initial Reintroduction Success in Long-Lived Primates by Quantifying Survival, Reproduction, and Dispersal Parameters: Western Lowland Gorillas (Gorilla gorilla gorilla) in Congo and Gabon

  • Tony King
  • Christelle Chamberlan
  • Amos Courage


Postrelease monitoring is an important aspect of reintroduction projects, one outcome of which is to allow an assessment of the initial success of the reintroduction, often measured by quantifying survival and reproduction rates. In long-lived species, accurate estimations of demographic parameters are difficult to obtain, and therefore assessment of reintroduction success in such species is challenging. To assess the initial success of a reintroduction program for the long-lived, slow-reproducing, and critically endangered western lowland gorilla Gorilla gorilla gorilla, we analyzed postrelease monitoring data from 2 reintroduced populations, in the Batéké Plateau region of the Republics of Congo and Gabon, to quantify several demographic parameters, and compared our results with published data on wild gorilla populations. Annual survival rate of the 51 released gorillas was 97.4%, 9 females gave birth to 11 infants at an annual birth rate of 0.196 births per adult female, and first-year survival of the infants was 81.8%. Annual birth rate within the reintroduced populations is not significantly different from that given for wild western gorilla populations, and other demographic parameters fall within the range of published data for wild gorilla populations. Our analysis illustrates that the reintroduction program has been successful in terms of the initial measures of postrelease survival and reproduction, and our quantitative data should facilitate the development of a population model that can predict the probability of population persistence and therefore provide an indication of longer-term reintroduction success.


Batéké Plateau Demography Great apes Postrelease monitoring 



We thank the Ministry of Forest Economy of the government of Congo, the Ministry of Water and Forests and the National Agency for National Parks of the government of Gabon, and The Aspinall Foundation of UK for their long-term commitment to and funding of the reintroduction and protected area management projects. We also thank the Wildlife Conservation Society (USA), Florent Ikoli, Mbani Akangala Mankarika, and Roland Missilou-Boukaka (Congolese government); and Adrien Noungou, Pierre Ngavoura, Mamadou Ntsoumou, and René Bazin Assaly (Gabonese government) for their contribution to protected area management and conservation within the Batéké Plateau; Liz Pearson, Paul Aczel, and Sandrine Mahé for significant contributions to earlier versions of this article; and Joanna Setchell and 3 anonymous reviewers for their constructive comments on the article. The information presented here results from 2 decades of dedicated work by numerous project staff, all of whom we deeply thank and without whom this program would never have been possible.


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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Tony King
    • 1
    • 2
  • Christelle Chamberlan
    • 1
    • 2
  • Amos Courage
    • 3
  1. 1.The Aspinall FoundationBrazzavilleRepublic of Congo
  2. 2.The Aspinall FoundationAntananarivoMadagascar
  3. 3.The Aspinall FoundationHytheUK

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