Bonobos (Pan paniscus) are being extensively hunted in Africa's Congo Basin.© WWF-Canon / Russell A. Mittermeier

Preliminary results from a survey of bonobos in Africa's Congo Basin suggest that their numbers are far lower than conservationists had thought. The discovery raises fears that one of our closest relatives may be teetering on the verge of extinction.

Researchers from the Congolese Institute for Nature Conservation and the New York-based Wildlife Conservation Society have surveyed around a third of the 36,000-square-kilometre Salonga National Park in the Democratic Republic of Congo. They did not see a single bonobo (Pan paniscus) in the flesh, and evidence from nests and dung suggests that the apes have become very scarce.

If the survey results represent a more general trend, there may be as few as 10,000 bonobos, also called pygmy chimpanzees, left in the wild, the researchers estimate. Experts had previously thought that there might be around 50,000 remaining.

Deadly shots

Poaching is to blame, says Peter Stephenson of the WWF, the conservation organization that supported the survey. Although it is illegal to kill bonobos, park officers have struggled to enforce the law during the long-running Congolese civil war, and armed militia groups still hide out in the wilderness of the Salonga park.

If the picture looks bleak for Salonga's bonobos, things may be even worse for those living elsewhere in the Congo Basin, which contains the world's entire population of the apes. "Salonga is a national park, we can only assume that poaching outside the park is even worse," Stephenson says.

If the bonobo does die out completely, we will have to say goodbye to perhaps our closest animal relative. The news from Salonga comes 75 years after P. paniscus was officially recognized as a distinct species from the more widespread common chimpanzee (P. troglodytes).

Stephenson hopes it won't come to that. "Saying they're effectively extinct is a bit too pessimistic, but it's a pretty desperate situation," he told news@nature.com.

The WWF is investing in antipoaching efforts and working to stop poachers encroaching on Salonga, particularly along river routes. And researchers from the Zoological Society of Milwaukee, Wisconsin, have launched a programme to monitor a particular band of bonobos in the park.

Next year the WWF hopes to appoint a park adviser to ensure that the apes are protected as much as possible. "Law enforcement in such a huge wilderness is very difficult," Stephenson admits. But failure could spell death for one of Africa's most charismatic animals. 

WWF