Mondika Gorillas
Western Gorillas

Photograph by: Ian Nichols, National Geographic January 2008

Western lowland gorillas, one of four gorilla subspecies, inhabit swampy forests only a few hundred feet above sea level in the Congo Basin of central Africa. They live and travel in small groups that consist of a silverback male, his female mates, and their offspring.

Although there are tens of thousands of western gorillas left in the wild, the World Conservation Union (IUCN) recently changed the status of the great apes from “endangered” to “critically endangered.” One of the major threats is the Ebola virus, which has killed up to 95 percent of the apes in areas of Gabon and the Republic of the Congo over the past 20 years.

Researchers aren’t exactly sure how gorillas acquire and pass on Ebola, but they suspect that the virus rapidly became widespread among the western lowland subspecies because of their feeding and ranging habits. The gorillas travel long distances every day to find food, especially fruit, and their paths often overlap: Individuals from different groups frequently feed at the same trees and in the same swamps. It could be that the infected gorillas leave tainted urine, saliva, and feces on and around trees that are then visited by other gorillas. Researchers have also documented that gorillas are curious about their dead and inspect carcasses they come across, putting them at risk of contracting Ebola.

Scientists are working on an Ebola vaccine for gorillas and chimpanzees. It’s still in the development stage, but several experimental vaccines tested on laboratory monkeys have proved successful. In the works are field trials to establish the best way to deliver a vaccine, either by darting or by oral baiting. These trials are in their earliest stages—no actual vaccine is used—and focused on determining how difficult it is to dart the notoriously elusive gorillas and which baits they’ll eat.


“In the Presence of Giants.“ National Geographic (January 2008), 88-105.

Behavioral Ecology of Western Gorillas Special Issue. American Journal of Primatology (October 2004)..

Bradley, Brenda, and others. “Dispersed Male Networks in Western Gorillas.” Current Biology (March 23, 2004), 510-13.

Caldecott, Julian, and Lera Miles, eds. World Atlas of Great Apes and Their Conservation. University of California Press, 2005.

Doran-Sheehy, Diane, and others. “Habituation of Western Gorillas: The Process and Factors That Influence It.” American Journal of Primatology (Vol. 69, 2007), 1-16.

Taylor, Andrea, and Michele Goldsmith, eds. Gorilla Biology: A Multidisciplinary Perspective. Cambridge University Press, 2003.

Other Resources

Published twice a year in English, German, and French, the Gorilla Journal features articles on the latest gorilla research, conservation, and ecotourism.

The Ebola virus has ravaged western gorilla populations, killing up to 95 percent in some areas. Find out more about this crisis and the efforts to stem the advance of the disease—and what you can do to help.

Learn about the Wildlife Conservation Society’s work in conserving prime wildlife habitat in the Congo Basin.

More information on the conservation status of gorillas.

Western gorillas

Photography and video

Last updated: December 2007