Photos Reveal First Tool Usage in Wild Gorillas

Newswise — For the first time ever, scientists have observed and photographed wild gorillas using tools, in one instance employing a stick to test the depth of a pool before wading into it, according to a study by the Bronx Zoo-based Wildlife Conservation Society (WCS) and other organizations. Up to this point, all other species of great apes, including chimpanzees and orangutans, have been observed using tools in the wild, but never gorillas. "This is a truly astounding discovery," said Thomas Breuer of the Wildlife Conservation Society. "Tool usage in wild apes provides us with valuable insights into the evolution of our own species and the abilities of other species. Seeing it for the first time in gorillas is important on many different levels." According to the study published in the open access journal PLoS Biology, on two separate occasions in the northern rain forests of the Republic of Congo, researchers observed and photographed individual western gorillas using sticks as tools. The observations were made in Mbeli Bai—a swampy clearing located in Nouabalé-Ndoki National Park where monitoring has been ongoing since February 1995. The first instance occurred when a female gorilla nicknamed Leah by scientists attempted to wade through a pool of water created by elephants, but found herself waist deep after only a few steps. Climbing out of the pool, Leah then retrieved a straight branch from a nearby dead tree and used it to test the depth of the water. Keeping her upper body above water, she moved some 10 meters out into the pool before returning to shore and her wailing infant.

Then another female gorilla named Efi used a detached trunk to support herself with one hand while digging for herbs with the other. As she moved from location to location, she used the stick for one last job, a bridge over a muddy patch of ground.

In the past, gorillas have been observed using tools in zoos, but not in the wild. And, while most other observed instances of tool-usage in great apes are related directly to processing food (i.e. the cracking of nuts with rocks or extracting termites with long sticks), these two examples of using tools for postural support were triggered by other environmental factors. The Wildlife Conservation Society has been studying gorillas and other wildlife in the Republic of Congo since the 1980s. In 1993, the Congolese Government, working in tandem with technical assistance from WCS, established Nouabalé-Ndoki National Park. The Mbeli Bai site is being managed to meet long-term gorilla research and ecotourism objectives. "These protected areas are not only important for the conservation of species they contain, they also hold the key to comparing our own development as a species with our next of kin," added Breuer. "Places like Nouabalé-Ndoki, and the nearby Goualougo Triangle, are places where we see the process unfolding before our very eyes." An exclusive look at this scientific discovery, including never-before-seen photographs and interviews in Africa with the field scientists who observed and documented the behavior for the first time, will be broadcast as the lead segment in the launch episode of "Wild Chronicles," a brand new series airing nationally on PBS stations beginning October 1, 2005 (check local listings). Hosted by Boyd Matson, the weekly, half-hour, science and nature adventure TV series will be presented nationally by PBS member station WLIW New York. The Mbeli study appears in PLoS Biology, a peer-reviewed, highly cited journal published by the Public Library of Science (PLoS), a non-profit organization committed to the goals of open access, making scientific and medical literature a public resource.

This study is immediately available online on the PLoS website without cost to anyone, anywhere to read, download, redistribute, include in databases, and otherwise use—subject only to the condition that the authors and source are properly cited.