An epidemic of Ebola hemorrhagic fever in central Africa could, combined with hunting, push Africa's apes close to extinction within the next decade, according to a report published online yesterday in Nature. The enormity of Ebola's impact became clear in January, when researchers found that up to two-thirds of the gorillas in the Lossi sanctuary in the northern part of the Democratic Republic of Congo--600 to 800 animals--had likely fallen to the virus since November. "It is a disaster," says primatologist Magdalena Bermejo of the University of Barcelona, Spain.
Until recently, says ecologist Peter Walsh of Princeton University in New Jersey, experts have believed that ape populations in Gabon and Congo, home to 80% of the world's gorillas and most common chimps, were stable because these countries retain much of their original forest cover. But Walsh suspected that hunting and, in the 1990s, Ebola was having a heavy impact. To quantify the losses in Gabon, Walsh and 22 co-authors from Europe, the United States, and Gabon (including Bermejo) compared a survey of ape nest sites in the early 1980s with survey results from 1998-2002.
The team found that the number of nest sites has fallen drastically, especially close to towns, where demand for bushmeat spurs hunting. Ebola may also be playing a major role: The virus has been detected in ape carcasses after some die-offs, and the survey indicated fewer apes close to human Ebola sites.
In total, ape populations have declined by an estimated 56% in Gabon since 1983. Walsh predicts they could fall another 80% within 3 decades, although "our decline rate is way conservative," he says. Anthropologist Alexander Harcourt of the University of California, Davis, agrees. He had earlier argued that the apes were safe, but things have changed: "It looks more serious than people had been thinking."
The team urges that the status of lowland gorillas and chimps be upgraded from endangered to critically endangered. They also call for immediate actions, including better law enforcement on park boundaries to stop poaching and studies of Ebola dynamics among apes. More than 100 people have died from Ebola in Congo this year. The possibility that ape-to-ape transmission is spreading the virus is "certainly a lead that we need to pay attention to," says Ebola vaccine researcher Gary Nabel of the National Institutes of Health in Bethesda, Maryland.