Ebola, Hunting Put Apes On Path to Extinction

NEW YORK, New York, April 8, 2003 (ENS) - Illegal hunting and the Ebola virus are decimating gorilla and chimpanzee populations in remote areas of Western Equatorial Africa, according to a new study from the Wildlife Conservation Society based at New York's Bronx Zoo.

The discovery is alarming to conservationists because many believed that ape populations in these densely forested, remote regions in Gabon and the Republic of Congo were relatively stable. Some 80 percent of wild gorillas and most wild chimpanzees are estimated to live in this area of West Africa.

The researchers, who reported their findings in the April 6 online edition of the journal "Nature," say that these populations have dropped by at least 50 percent over the past 20 years.

"This is a catastrophic decline of great apes in an area that contains the bulk of the world's remaining populations," said Peter Walsh, lead author of the study and a Princeton University ecologist.

"The species that are most similar to humans are just disappearing before our eyes," said Walsh.

Walsh led an international group of 23 researchers, who coordinated and conducted several surveys between 1998 and 2002. The team surveyed ape habitat and populations over some 4,800 square kilometers (1,853 square miles) of dense jungle, mostly within Gabon.

Chimpanzees are humankind's closest living relative, sharing 98.4 percent of human DNA. (Photo courtesy United Nations Environment Programme (UNEP))

It is comparisons with earlier studies that offer the stark evidence that wild apes are in serious trouble. For example, a 1991 study found 67 ape nest groups along a straight 20 kilometer (12 mile) line of the forest. In 1997 and 1998, observations in the same area, but over a 2,700 kilometer (1677 mile) distance found only 91 nest groups.

"Those who work in the field have had an idea of what is happening, both the hunting and the Ebola, for a while now, but it has been under the public radar," said Walsh.

"Ours is a rigorous, quantitative estimate that I hope people will pay attention to," Walsh said. "If you ask anybody, even in the international conservation community, they will tell you that there are lots of apes. The fact is there are not. They have really been hammered, and it is actually accelerating."

This new evidence provides such a grim picture because it documents that habitat alone is not enough to sustain wild ape populations.

Habitat destruction had been listed as the leading threat to wild apes, with a 2002 report from the United Nations Environment Programme predicting that less than 10 percent of the remaining wild ape habitat in West Africa will be intact by 2030 if the current level of forest development continues.

"If chimpanzees and gorillas are in trouble in Gabon, an area known for its pristine, unbroken forests, than we have a species wide crisis on our hands when it comes to saving these animals," said Lee White, a conservationist with the Wildlife Conservation Society. White has worked in Gabon for the past decade.

The researchers involved in this latest study warn the decline of the great apes could be even worse outside of the surveyed areas of Gabon.

The Ebola virus was first identified in a western equatorial province of Sudan and in a nearby region of Zaire, now Congo, in 1976. (Photo courtesy World Health Organization)

But knowing how to address the underlying reasons for the decline of wild ape populations is far from easy. The researchers report that the increase in mechanized logging continues to negatively impact apes, bringing thousands of workers deep into forest habitat.

Increased demand for bushmeat has followed the logging operations, which have also carved roads through the forest that make it easier for poachers to track down wild apes.

Ape meat is only a small percentage of bushmeat, perhaps as low as one to two percent. Still, it has a severe impact on these ape species because they have slow reproduction rates. The bushmeat trade is considered to be the largest threat to wild chimpanzees.

Petroleum operations in the forests of the Congo, as well as forest conversion for agricultural use, have similar effects to those from the logging described in the study.

Strong law enforcement, in the few areas where it occurs, has cut down on some poaching, according to Walsh.

But it takes political will and money, he said, "both of which have been lacking in the past."

The threat to apes from Ebola, however, could be even more difficult to combat. Ebola is one of the world's most virulent viral diseases, killing some 50 percent to 90 percent of all clinically ill cases, and it is a disease still poorly understood by scientists.

Gorillas are very shy and difficult to track in the wild. (Photo courtesy UNEP)

Thousands of wild apes are believed to have perished from Ebola, but it is still unknown whether it can be passed from ape to ape or to other animals.

WCS has warned that Ebola is very close to Odzala National Park, which is a stronghold of wild ape populations.

The researchers found that the density of ape nests varied according to how far the site was from one of Gabon's four major cities and how far it was from a documented Ebola outbreak.

They raised the concern that shrinking habitat could push individual groups of apes closer together, increasing the risk of an Ebola epidemic.

Walsh said immediate funding for Ebola research is needed, and he called on the U.S. Congress to make a $10 million emergency supplement to the U.S. Fish and Wildlife Service Great Ape Conservation Fund earmarked specifically for Ebola field research and intervention.

Coordination among with the local people living near gorilla and chimpanzee habitat will be essential for any strategy to succeed, he said.

Researchers warn the extent of population decline among wild apes could be even worse than the survey reports. (Photo courtesy Wild Chimpanzee Foundation)

The threat to wild apes, Walsh says, merits listing apes as "critically endangered" in the IUCN-World Conservation Union Red List of Endangered Species. Gorillas and chimpanzees are currently listed as "endangered" by the IUCN.

"If chimps and gorillas continue to disappear at the current rate, our closest relatives will be confined to a few small pockets in a matter of years," Walsh said.

These pockets are not sustainable and could heighten the risks from Ebola, the researchers reported.

"The stark truth is that if we do not act decisively our children may live in a world without wild apes," Walsh said.