for National Geographic News
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.
(See also: "Extinction Threatens Half of Primate Types, Study Says" [August 5, 2008].)
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.
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