SCIENCE -- October 26, 2010 at 6:50 PM ET
Biodiversity Losses are Alarming, but Reversible
The black-footed ferret, once thought extinct, has been successfully reintroduced to parts of its former habitat.
A decade-long effort involving nearly 200 scientists and a colossal database has reached a simple conclusion: conservation works. But there's not enough of it.
Roughly 20 percent of the world's vertebrate species are classified as threatened, according to an article published online Tuesday by the journal, Science. This means a staggering 41 percent of all amphibians are declining rapidly and facing severe threats, along with 25 percent of mammals, 13 percent of birds and 22 percent of reptiles.
For the first time, researchers have attached a number to the loss rate of the world's vertebrate species. Each year 52 mammals, birds and amphibians move one category closer to extinction, they report.
But in the absence of conservation efforts, declines would have been about 18 percent worse, the survey shows. In other words, much of this species loss can be reversed.
This paper comes as world leaders are convening this week at a United Nations biodiversity summit in Nagoya, Japan, to set targets to combat biodiversity loss, after a promise at the 2002 Convention on Biodiversity to cut the rate of species extinctions by 2010 failed to meet its targets.
To reach the latest findings, 174 scientists, working on a volunteer basis, analyzed 25,000 species from the International Union for Conservation of Nature's "red list," the most comprehensive global tally of the conservation status of plants and animals. Amphibians have been hardest hit, devastated by a fungal pathogen called the chytrid fungus, which now threatens one-third of the world's frogs, toads and salamanders. Many of these animals have restricted habitat ranges, with ongoing habitat loss pushing them closer to extinction.
The report documents how severe the situation is for vertebrates, but shows that we have the tools and knowledge to bring many species back from endangered status, says Michael Hoffmann of the IUCN, and the study's lead author.
"The impact, the collective impact of conservation's success is what we demonstrate in this paper," he says. "What we show is yes, absolutely, things are deteriorating, but without conservation, things would be much worse."
He points to long recovery efforts that have brought the black-footed ferret, the golden tamarin and the California condor back from the brink of extinction. Such efforts range from breeding animals in captivity and then reintroducing them into the wild, to building fences to actively guard important animal habitat.
Galen Rathbun, a California-based mammologist, worked with a team that studied 75 species of afrotheres, a group of ancient African animals that includes elephant shrews, aardvarks, hydraxes and golden moles. The research required a massive team effort, he said.
"Almost all IUCN specialists are composed of volunteers," he said. "They all have real jobs that put food on the table... so you're pushing and pulling on people's time. It was over a year and a half of slowly pulling all the information together."
Factors behind the species decline are broad and varied in scope, but include logging, land expansion, hunting and overfishing. The common driver behind all of it, Rathbun points out, is people.
"There are very few cases where species are dramatically declining, where you can't trace the cause directly to people. Habitat disruption, poaching, the use of chemicals... it's almost always related to many of us."
Doug Inkley, senior scientist for the National Wildlife Federation and a wildlife conservation expert, says he hopes these findings will fuel more funding for threatened species.
"Success efforts are often underrated, frankly," he said. "Hopefully, this paper will show that when we want to do it, we can."
While the report's findings on conservation are heartening, its conclusion lays out a series of daunting obstacles. With the magnitude of the threat eclipsing the current level of action and many recovered species still dependent on conservation, efforts must be dramatically scaled up to combat the problem.
"This is not to say that things are rosy," Hoffmann says. "We still need a hell of a lot more to remedy the shortfall that currently exists."