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Catastrophic ape decline in western equatorial Africa


Because rapidly expanding human populations have devastated gorilla (Gorilla gorilla) and common chimpanzee (Pan troglodytes) habitats in East and West Africa, the relatively intact forests of western equatorial Africa have been viewed as the last stronghold of African apes1. Gabon and the Republic of Congo alone are thought to hold roughly 80% of the world's gorillas2 and most of the common chimpanzees1. Here we present survey results conservatively indicating that ape populations in Gabon declined by more than half between 1983 and 2000. The primary cause of the decline in ape numbers during this period was commercial hunting, facilitated by the rapid expansion of mechanized logging. Furthermore, Ebola haemorrhagic fever is currently spreading through ape populations in Gabon and Congo and now rivals hunting as a threat to apes. Gorillas and common chimpanzees should be elevated immediately to ‘critically endangered’ status. Without aggressive investments in law enforcement, protected area management and Ebola prevention, the next decade will see our closest relatives pushed to the brink of extinction.

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Figure 1: Western equatorial Africa.
Figure 2: Ape nest encounter rates in Gabon.
Figure 3
Figure 4: Decline and recovery projections.


  1. Oates, J. F. African Primates: Status Survey & Action Plan (IUCN, Cambridge, 1996)

    Book  Google Scholar 

  2. Harcourt, A. H. Is the gorilla a threatened species? How should we judge? Biol. Conserv. 75, 165–176 (1996)

    Article  Google Scholar 

  3. Minnemeyer, S., Walker, T., Collomb, J. G., Cotton, L. & Bryant, D. An Analysis of Access to Central Africa's Rainforests (World Resources Institute, Washington, 2002)

    Google Scholar 

  4. Roberts, L. (ed.) World Resources 292 (Oxford Univ. Press, New York, 1998)

  5. Tutin, C. E. G. & Fernandez, M. Nationwide census of gorilla (Gorilla g. gorilla) and chimpanzee (Pan t. troglodytes) populations in Gabon. Am. J. Primatol. 6, 313–336 (1984)

    Article  Google Scholar 

  6. Georges, A. J. et al. Ebola hemorrhagic fever outbreaks in Gabon, 1994–1997: Epidemiologic and health control issues. J. Infect. Dis. 179, S65–S75 (1999)

    Article  Google Scholar 

  7. Chamberlin, C. Migration of Fang into central Gabon during the 19th century—a new interpretation. Int. J. Afr. Hist. Stud. 11, 429–456 (1978)

    Article  Google Scholar 

  8. Pourtier, R. Le Gabon Vol. 1 (Harmattan, Paris, 1989)

    Google Scholar 

  9. Wilkie, D. S., Shaw, E., Rotberg, F., Morelli, G. & Auzel, P. Roads, development, and conservation in the Congo Basin. Conserv. Biol. 14, 1614–1622 (2000)

    Article  Google Scholar 

  10. Rapport des activites de la Lutte Antibracionnage, Brigade de Faune de la Lope (Direction de la Faune et de le Chasse, Libreville, Gabon, 1999).

  11. Angoué, C. et al. in L'avenir des peuples des forêts tropicales—Rapport final Vol. III (eds Bahuchet, S. & de Maret, P.) (Université Libre de Bruxelles, Brussels, 2000)

    Google Scholar 

  12. Huijbregts, B., de Wachter, P. & Ndong Obiang, L. S. Ebola and the decline of gorilla (Gorilla gorilla) and chimpanzee (Pan troglodytes) populations in the Minkebe Forest, north-eastern Gabon. Oryx (in the press)

  13. Lahm, S. A. Ecology and Economics of Human/Wildlife Interaction in Northeastern Gabon. Dissertation, New York Univ. (1993)

    Google Scholar 

  14. Brugière, D. & Sakom, D. Population density and nesting behaviour of lowland gorillas (Gorilla gorilla gorilla) in the Ngotto forest, Central African Republic. J. Zool. 255, 251–259 (2001)

    Article  Google Scholar 

  15. Barnes, R. F. W., Barnes, K. L., Alers, M. P. T. & Blom, A. Man determines the distribution of elephants in the rain forests of northeastern Gabon. Afr. J. Ecol. 29, 54–63 (1991)

    Article  Google Scholar 

  16. Bermejo, M. Status and conservation of primates in Odzala National Park, Republic of the Congo. Oryx 33, 323–331 (1999)

    Article  Google Scholar 

  17. Blom, A. The monetary impact of tourism on protected area management and the local economy in Dzanga-Sangha (Central African Republic). J. Sust. Tourism 8, 175–189 (2001)

    Article  Google Scholar 

  18. Wilkie, D. S. & Carpenter, J. Can nature tourism help finance protected areas in the Congo Basin? Oryx 33, 333–339 (1999)

    Article  Google Scholar 

  19. Buckland, S. T., Anderson, D. R., Burnham, K. P. & Laake, J. L. Distance Sampling: Estimating Abundance of Biological Populations (Chapman & Hall, London, 1993)

    MATH  Google Scholar 

  20. Walsh, P. D. & White, L. J. T. What it will take to monitor forest elephant populations. Conserv. Biol. 13, 1194–1202 (1999)

    Article  Google Scholar 

  21. Hedley, S. L., Buckland, S. T. & Borchers, D. L. Spatial modelling from line transect data. J. Cetacean Res. Manage. 1, 255–264 (1999)

    Google Scholar 

  22. Kingdon, J. The Kingdon Field Guide to African Mammals (Academic, San Diego, 1997)

    Google Scholar 

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This paper is dedicated to Annelisa Kilbourn who died on 2 November 2002 in a plane crash en route to her Ebola research site. For support of ape survey work we thank USAID-CARPE, the DGIS, the MacArthur Foundation, WCS, WWF and the Republique Gabonaise. Funding for the socioeconomic surveys was provided by NSF. D. Purves, S. Sandin and J. Regetz provided helpful comments on statistical analyses.

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Correspondence to Peter D. Walsh.

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Walsh, P., Abernethy, K., Bermejo, M. et al. Catastrophic ape decline in western equatorial Africa. Nature 422, 611–614 (2003).

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