Ability To Survive Initial Deforestation No Aid To Endangered Birds - Duke

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DURHAM, N.C. -- "Deep-woods bird species that manage to hang on in remaining patches of a deforested area of Brazil gain no real advantage in avoiding extinction, Duke University ecologists have found. The researchers studied the coastal region harboring the greatest number of threatened birds in the Americas. "We found that species that also tolerate secondary habitats are not deforestation's survivors," said Grant Harris, the first author of a paper on the subject published in the December issue of the research journal "Conservation Biology."

"If you lose your habitat, everybody is equally threatened," added Harris' co-author, Stuart Pimm. "There's no special class of species that seems to adapt well to the habitats we create for them."

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"Deforestation is rarely total or completely permanent," the two authors wrote in their "Conservation Biology" paper. "Small patches of original habitat remain and, in time, secondary forests, gardens or plantations replace some cleared areas." Given that reality, the two authors designed a study to explore how well some species survive in deforested habitat and whether some surviving species can persist in such landscapes. Their study focused on Brazil's Atlantic Forest, which the authors estimate now has been reduced to 119,540 square kilometers, or about 10 percent of its original extent. "There are more species threatened with extinction in this coastal strip of rain forest than anywhere else in the Americas," Pimm said in an interview. "Starting maybe 75 years ago people began moving inland from the coastal cities that have been settled for 500 years. As a consequence, very little of the coastal forest in the lowlands now remains. Much of what remains is in impenetrable mountains." Deforestation along the approximately 800-mile-long coastal strip is also drying out the highlands further west, Pimm added. "As the lowlands area cleared, they become hot," he said. "And the uplands then begin to suffer because they're not getting the flow of moist air off the land."

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What emerged was their own estimate of remaining distributions of two categories of bird species. Those categories were "forest obligate" birds that cannot exist outside the deep woods and purported "survivor" birds that could make do in more marginal "secondary habitats." "There is a subset of forest endemic birds that are also seen in other secondary habitats like gardens, plantations and golf courses," Harris said. "This has led some researchers to claim that if entire regions were completely deforested, this subset of forest endemic birds will not go extinct because they also tolerate secondary habitats." But their Conservation Biology paper found otherwise. "We found no survivors," they wrote. "Habitat loss threatens forest-obligate birds and those using secondary habitats equally."

(Emphasis added)

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http://www.eurekalert.org/pub_releases/2004-11/du-fhn113004.php