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.
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