Rainforest Logging in Africa May Doom Half of Bird, Primate Species

Monitor Wire Services

Fragmented rainforests can keep losing biodiversity for a century, and 30 percent of African primates should be considered 'living dead' because they are doomed, according to two recent articles in the journal Conservation Biology.

"There is no room for complacency," says Thomas Brooks of the University of Arkansas in Fayetteville, who with colleagues studied the extinction of bird species in five fragments of Kakamega Forest, Kenya's only rainforest. The researchers determined the rate of bird extinction based in part on how long the fragment has been isolated and on the number of bird extinctions during that time. To check their method, they showed that it accurately accounts for the number of species that have been lost in eastern North America, where deforestation peaked 150 years ago.

Brooks and his colleagues found that within 50 years of isolation, 2,500-acre fragments of Kakamega Forest lose half the bird species likely to go extinct. They concluded that it will take about a century for fragmented tropical rainforests to lose all the bird species that will ultimately die out.

"Our results provide both encouragement and warning," say Brooks and his colleagues.

The warning is that without action, half of the world's 360 threatened forest bird species will be extinct in about 50 years. The encouraging conclusion is that because the most-recently isolated fragments probably still have most of their species, conserving these fragments will mean saving the greatest number of species.

Despite huge losses of tropical forests worldwide, no primates are known to have died out there since the year 1600. But the primates aren't all safe. Rather, it just takes a long time for them to die out, according to new research.

"We should not be lulled into a false sense of security when we see that many species have survived habitat loss in the short term," says Guy Cowlishaw of the Zoological Society of London. "Many are not actually viable in the long term. These might be considered 'living dead.'"

Cowlishaw determined how many primate species are likely to go extinct in African forests. He based his prediction on two things: 1) the well-documented relationship between species number and habitat size, and 2) the extent of deforestation in African countries.

Cowlishaw's results suggest that the amount of deforestation so far has left Africa with a sizeable "extinction debt." For instance, even without losing any more forest, six countries (Benin, Burundi, Cameroon, Ivory Coast, Kenya and Nigeria) could lose a third to half of their forest primate species within decades. Actual extinctions could be much higher because West Africa is expected to lose 70 percent and East Africa 95 percent of the remaining forest cover by 2040.

Habitat loss threatens about half of primate species worldwide. Determining where the extinction debts are the greatest will help conservationists decide where to restore habitat and establish corridors between fragments.

Both studies were published in the October issue of Conservation Biology.