New estimate brings world population of mountain gorillas to 880

NEW YORK (December 3, 2012)—A 2011 census of mountain gorillas in Uganda’s Bwindi Impenetrable National Park has confirmed that the great apes there have increased in number since the last count in 2006, according to the Wildlife Conservation Society, which provided support for the census.

Recently released by the Uganda Minister for Tourism, Wildlife, and Antiquities and the Uganda Wildlife Authority, the new census reveals a minimum population of 400 gorillas, up from 302 animals in 2006. The census was conducted by the Uganda Wildlife Authority, the Institut Congolais pour la Conservation de la Nature (ICCN) from the Democratic Republic of Congo and the Rwanda Development Board (RDB). The increase can be attributed in part to improved methodology, but also reflects real population growth.

When combined with the estimated 480 gorillas inhabiting the Virunga Volcanoes to the south (the only other location where mountain gorillas exist) , the world’s population of mountain gorilla now stands at 880. The mountain gorillas of Bwindi and the Virungas are the only gorilla populations known to be increasing; all other populations are thought to be in decline due to hunting and habitat loss.

“The latest census of mountain gorillas in Bwindi provides the conservation community with much needed good news,” said Dr. Liz Macfie, Gorilla Coordinator for the Wildlife Conservation Society. “The results also show us that enforcement efforts by the Uganda Wildlife Authority there are paying off.”

In addition to finding an increase in Bwindi’s gorilla population, the census participants have also improved on their methodology in order to produce more accurate data. For the latest effort, teams covered the national park twice, as opposed to only one pass for previous census work, to ensure a more complete inventory of gorillas in the landscape. Also, researchers augmented the traditional techniques of nest counts and dung collection with a genetic analysis of fecal matter collected during the census (the latter being a modified version of mark-recapture methods).

The rise in mountain gorilla populations also indicates the success of a continued collaboration between the Uganda Wildlife Authority with the Institut Congolais pour la Conservation de la Nature (ICCN) in the Democratic Republic of Congo and the Rwanda Development Board (RDB); the Virunga Mountains lie on the borders of three countries, requiring the participation of agencies from Uganda, Democratic Republic of Congo, and Rwanda for effective monitoring and enforcement. Bwindi, however, is located in Uganda, but in the spirit of regional collaboration, the ICCN and RDB sent support teams for the 2011 Bwindi census effort.

“We commend the census organizers for a well-organized field effort,” said Dr. James Deutsch, WCS’s Executive Director for Africa Programs. “WCS is proud to be part of what has become the gold standard of effective conservation teamwork in the effort to save our closest of kin.”

The census was organized by the International Gorilla Conservation Programme and the Max Planck Institute for Evolutionary Anthropology, which also conducted the genetics analysis. Other partners included Conservation Through Public Health, the Mountain Gorilla Veterinary Project, the Institute for Tropical Forest Conservation (a WCS-associated research center), and the Dian Fossey Gorilla Fund International. Funding for the census was provided by WWF-Sweden, with additional support from WCS, Berggorilla & Regenwald Direkthilfe e.V., and the Max Planck Institute for Evolutionary Anthropology. Government partners for the project include the U.S. Agency for International Development’s Central African Regional Program for the Environment and the U.S. Fish and Wildlife Service’s Great Ape Conservation Fund.

Although far fewer in number than their western relatives, mountain gorillas have had a profound effect on both the public and the naturalists who have encountered them. While collecting specimens in Africa for the American Museum of Natural History in the early 20^th Century, U.S. explorer Carl Akeley became concerned about the future of the mountain gorilla, helping to establish Africa’s first national park—now Virunga National Park—in 1925 to protect the gorillas.

In the late 1950s, WCS field biologist Dr. George Schaller conducted the first ecological study of mountain gorillas, estimating the total population at that time to be 450 individuals. The Virunga Volcano gorillas were made world-famous by Dr. Dian Fossey’s long-term gorilla study in the 1970s and 80s, a period during which the gorilla population declined dramatically as a result of poaching and habitat loss. In 1979, WCS conservationists Drs. Bill Weber and Amy Vedder helped establish the Mountain Gorilla Project—forerunner of the International Gorilla Conservation Programme (IGCP) —that combined pioneering ecotourism and education programs, with a more traditional anti-poaching effort.