Chimpanzees' last stronghold in danger as numbers fall by 90%

Richard Alleyne, The Telegraph 13 Oct 08;

Time appears to be running out for chimpanzees living in the wild after a survey of its last "stronghold" found numbers had plummeted by 90 per cent.

The effect of man had already led to a reduction from an estimated 100,000 fifty years ago to between 12,000 and 8,000 in 1990 in the Ivory Coast, the west African country that harboured more than half the world's population of chimps.

But a new survey has found that it has dropped a further 90 per cent to little more than 1,000 individual chimps.

Now scientists believe there is only one viable population left in the Tai National Park and that the ape should be classified as "critically endangered".

Christophe Boesch, of the Max Planck Institute for Evolutionary Anthropology, told the journal Current Biology, that the rise in the human population was to blame.

"The human population in Cote d'Ivoire has increased nearly 50 per cent over the last 18 years," he said.

"Since most threats to chimpanzee populations are derived from human activities such as hunting and deforestation, this has contributed to the dramatic decline in chimpanzee populations.

"The situation has deteriorated even more with the start of the civil war in 2002, since all surveillance ceased in the protected areas."

The few remaining chimpanzees are now highly fragmented, with only one viable population living in Taï National Park, according to a report.

Chimpanzees are notoriously difficult to spot so researchers count the number of nests to estimate populations.

In the new study, the number of nests recorded by Boesch and his colleague Geneviève Campbell had dropped by 90 per cent since the last count.

They found the catastrophic decline in chimpanzees is especially strong in forest areas with low protection status, where the researchers saw no sign of the chimps.

Even in protected areas like Marahoué National Park, chimpanzees have clearly suffered since surveillance and external funding support were disrupted by civil unrest in 2002.

Campbell said. "It was saddening that I only found one nest in this park, as during the previous survey they found 234 nests. The one nest I did find was also in an area that had just been cleared for agriculture."

Even the last remaining refuge for the dwindling West African chimpanzees the Taï National Park is extremely threatened by poachers, Boesch said.

"We must appeal to the international conservation community to invest in sustainable funding of conservation activities in national parks with known importance for chimpanzee populations.

"External financial support in that park is scheduled to end in 2010, a move that will probably have disastrous consequences for the last vestiges of chimpanzees in Côte d'Ivoire."

Chimps 90 Percent Gone in a "Final Stronghold"
Rebecca Carroll, National Geographic News 13 Oct 08;

West African chimpanzees have declined by 90 percent in the last 18 years in an African country that is one of the subspecies' "final strongholds," a new study stays.

Scientists counting the rare chimps in Côte d'Ivoire (Ivory Coast) found only about 800 to 1,200 of the apes—down from about 8,000 to 12,000 in 1989-90. Before the new survey, the country had been thought to harbor about half of all West African chimps.

"We were not expecting such a drastic decrease," said lead author Geneviève Campbell, a doctoral candidate at the Max Planck Institute for Evolutionary Anthropology in Germany.

The 1989-90 survey had itself represented a significant decline from 1960s estimates of about a hundred thousand West African Chimps in Côte d'Ivoire.

Nowhere to Run

Since 1990 Côte d'Ivoire's human population has grown by about 50 percent. This growth is the most likely cause of the decline in the chimp numbers, according to the report.

More people has led to more hunting and deforestation—key chimp threats—particularly since 2002, when a coup attempt sparked civil unrest that continues today, the study says.

One of the country's sanctuaries, Marahoué National Park, has lost 93 percent of its forest cover in the last six years, the new survey found.

Campbell said that at many of the sites her team visited, "the habitat is gone, and all the protected areas have been invaded by people."

The human "invasion" has left wide swaths inhospitable to other forms of life, she suggests.

At many of the survey sites, "it's not just the chimps—[there's] no animal at all," said Campbell, speaking by phone from Côte d'Ivoire.

In Decline Elsewhere?

A similar decline may have taken place in other countries within the West African chimpanzee range, says the new report, which was published today in the journal Conservation Biology.

The largest remaining population of the subspecies is believed to be in Guinea. But that belief is based on counts that are more than a decade old, according to the study.

In the falling West African chimp numbers, scientists see a door closing on their ability to understand and protect the subspecies.

"We know very little, really, about West African chimps compared to our knowledge of the East African chimp species," said Jill Pruetz of Iowa State University via email.

"Populations in Ivory Coast seemed to me the one place (and, perhaps Guinea) where we could still look," added Pruetz. The biological anthropologist, who was not involved in the study, is a National Geographic Society emerging explorer. (The National Geographic Society owns National Geographic News.)

Ape expert Frans de Waal of Emory University in Georgia described the report as "depressing."

"This study focuses on one rare subspecies of chimpanzee, but the same poor prospects hold for apes in general," said de Waal, who was not involved in the new research.

De Waal fears the report is "one of many to come."

Conservation Works

During the recent study, in all but 3 of the 11 survey sites, researchers found significantly fewer chimp nests—platforms built of branches high in the trees—than had been found in 1989-90.

In Marahoué National Park, study co-author Campbell found only one nest, versus 234 in 1989-90.

Two of the sites where West African chimps have not declined had only a few to begin with.

The third site is Taï National Park, a UNESCO World Heritage site that has benefited from intensive research and conservation efforts, according to the report.

The Taï numbers suggest that the apes' numbers respond to stable conservation efforts, according to scientists involved with the research.

"We urgently need to locate the viable population of western chimpanzees" in order to protect them, Campbell said.

Emory University's de Waal said preventing illegal hunting would be key.

"Unless we can put a stop to poaching—not just forbidding it but actually monitoring and stopping it—these trends may continue," he said.