Some populations have fallen to just a few dozen. Main cause: habitat destruction.

Almost half of the world's primate species — which include apes, monkeys and lemurs — are threatened with extinction because of the destruction of tropical forests and illegal hunting and trade.

In a report highlighting the 25 most endangered primate species, conservationists have outlined the desperate plight of primates from Madagascar, Africa, Asia and Central and South America, with some populations down to a few dozen.

The golden headed langur, which is found only on the island of Cat Ba in north-eastern Vietnam, is down to 60 to 70 individuals. And there are fewer than 100 northern sportive lemurs left in Madagascar, and around 110 eastern black crested gibbons in north-eastern Vietnam.

Red list

Of the world's 634 primate species, 48 per cent are classified as threatened with extinction on the conservation group IUCN's “red list” of threatened species. The latest report was compiled by 85 primatologists working in the field.

“All over the world, it's mainly habitat destruction that affects primates the most,” said Christoph Schwitzer, head of research at the Bristol Conservation and Science Foundation and one of the authors of the report.

“Illegal logging, fragmentation of forests through fires, hunting is a big issue in several African countries and also now in Madagascar. In Asia one of the main problems is trade in hearts for traditional medicine, mainly into China.”

Russell Mittermeier, a primatologist and president of Conservation International, said:

“The purpose of our top 25 list is to highlight those that are most at risk, to attract the attention of the public, to stimulate national governments to do more, and especially to find the resources to implement desperately needed conservation measures ... we have the resources to address this crisis but so far we have failed to act.”

There are fewer than 320 Delacour's Langurs left in Vietnam, thanks to the trade in the animals' bones, organs and other tissues for traditional medicines. The Sumatran orang utan is down to around 6,600 due to fragmentation of their habitats and the removal of forest to make way for agricultural uses such as palm oil plantations.

Schwitzer said that the primate he monitors, the blue-eyed black lemur in Madagascar, has suffered from the rapid destruction of forests in recent years and now numbers no more than 2,300. “With the political crisis in Madagascar, this has been exaggerated in the last year or two, with lots more illegal logging.” Schwitzer hoped the new report would highlight the extent of the dangers facing some of humankinds' closest relatives in the wild.

“Support and action to help save these species is vital if we are to avoid losing these wonderful animals forever.” — © Guardian Newspapers Limited, 2010

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