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A new study finds that one-fifth of animal species are threatened with extinction. Under a treaty, nations of the world are supposed to be slowing the rate of extinctions. Biologists and diplomats are meeting in Japan today to see if the agreement is living up to its goal. NPR's Richard Harris has the story.
RICHARD HARRIS: If an ecology professor ever corners you in a bar, pretty soon you'll be hearing how important it is to preserve the diversity of life on Earth, to keep the world's ecosystems in balance and to preserve species directly useful to humans. If that professor happens to be Stuart Pimm from Duke University, the conversation's likely to move quickly to the role of extinction.
Professor STUART PIMM (Duke University): Species extinction is rather like death and taxes. They are an inevitable part of life, but you just don't want them to happen at too great a rate.
HARRIS: Pimm says right now extinctions are happening about 100 to 1,000 times the historical rate. And a study to be published in Science magazine shows that's especially worrisome for the very animals we're most likely to relate to: mammals like us, birds, and amphibians - vertebrates.
Ms. ANA RODRIGUES (Center for Functional and Evolutionary Ecology): What we've found is that overall about one in every five species are threatened with extinction.
HARRIS: Ana Rodrigues, from the Center for Functional and Evolutionary Ecology in Montpellier, France, is an author of that global analysis. And she says the worst off are the amphibians, thanks to a fungus that's deadly to frogs and has been sweeping the globe.
Ms. RODRIGUES: When it invades in a particular ecosystem, it could be just a few years before the entire population crashes.
HARRIS: And some species, like the golden toad in Costa Rica, have simply vanished. In all, the study finds that more than 800 species of vertebrates are moving closer to extinction.
But the study is not all bad news. The scientists identified more than 60 species that have improved in recent decades, thanks to concerted conservation efforts. Those include�everything from blue whales to a charismatic denizen of the American West - the black-footed ferret. Rodrigues says these ferrets were virtually wiped off the planet as ranchers killed off their food source, prairie dogs.
Ms. RODRIGUES: So they were extinct in the wild, which is pretty much as bad as it gets, other than extinct.
HARRIS: But biologists launched a major effort to raise the ferrets in captivity and then reintroduced them into the wild. The ferrets are still far from abundant, but their status has been upgraded from extinct in the wild to critically endangered and now to simply endangered.
Ms. RODRIGUES: Endangered is bad, but it's definitely not as bad as extinct in the wild.
HARRIS: The new study scores that as a success story. And many other species have been preserved by getting rid of invading predators, like cats and rats on isolated islands.
Ms. RODRIGUES: So the good news stories comes from the main threats a few decades ago. So a few decades ago the islands were where most of the species were going extinct.
HARRIS: But Stuart Pimm says those successes don't so much address present-day threats.
Prof. PIMM: The great majority of threatened species are not on islands. They're in areas where we're destroying the species' homes. And stopping that requires�different techniques.
HARRIS: So far, Pimm says, we're losing the battle to preserve habitat, particularly in places like southeast Asia, where palm oil plantations are rapidly replacing native forest. So�conservation biologists meeting in Japan today can demonstrate it's possible to save endangered species. But they know it will take a lot more effort to reverse the rapid downward trend.
Richard Harris, NPR News.