Half of all amphibian species at risk of extinction

A new study finds that more than 1,000 amphibian species poorly known to science are likely facing extinction, adding to the already identified 4,200 species the UN says are in peril.

EVIDENCE THAT THE world’s amphibians are in peril continues to mount.

In March, a study published in the journal Science found that 501 species of frogs and salamanders had been driven toward extinction by killer fungi known as chytrid. That’s more than twice the previous estimate.

Then earlier this week, a United Nations committee on biodiversity announced that human impacts are threatening the existence of some one million species, including 40 percent of all the amphibian species known to science, or about 3,200 species.

An ensatina salamander (Ensatina eschscholtzii eschscholtzii).
PHOTOGRAPH BY JOEL SARTORE, NATIONAL GEOGRAPHIC PHOTO ARK

And now a new study, published on May 6 in the journal Current Biology, has used statistical analysis to predict that another 1,100 species of amphibians currently listed as “data deficient” by the International Union for Conservation of Nature, which sets the global conservation statuses for plants and animals, should probably be added to the list.

If the team’s findings are correct, it would mean 4,300, or more than half the world’s frogs, salamanders, and caecilians are in danger of extinction.

But there’s a sliver of hope here.

“In the neotropics, the species that we know are threatened have very similar geographical distributions compared to the data deficient species predicted to be threatened,” says Pamela González del Pliego, an ecologist at Yale University and the study’s lead author. “Therefore, if we try and conserve the areas where current threatened species are, we will be protecting the data deficient species as well.”

What’s in a name?

Jonathan Kolby, a National Geographic Explorer and IUCN amphibian specialist group chair for Honduras, says he’s not surprised by the new statistics. However, he says there may be something even more important than the numbers here. And that’s a better understanding of what it means to be listed as “data deficient.”

The IUCN Red List of Threatened Species classifies animals as least concern, near threatened, vulnerable, endangered, critically endangered, extinct in the wild, and extinct. It also has a classification for “data deficient” species. In the simplest terms, when a species is listed as data deficient, it means that scientists don’t have enough information to assess its risk of extinction. Many factors that can lead to such a listing.

For instance, Kolby says newly discovered species are often labeled data deficient because so little is known about them. Likewise, some animals are more difficult to study than others. This is especially true of species that are small and cryptic, or those that live in remote habitats, as many amphibians do. Finally, certain branches of the tree of life garner a lot more scientific attention than others, especially charismatic mammals, and that leads to gaps in knowledge.

Whatever the case, Kolby says the IUCN has long struggled with the perception that data deficient species are somehow safe.

AMPHIBIANS FACE MASS EXTINCTION AS FUNGUS SPREADS ACROSS THE WORLD
Results from a recent global survey of amphibians shows that chytrid fungus has threatened twice as many species than previously thought.
VIDEO BY KATIE GARRETT AND JONATHAN KOLBY

“A lot of people look at the data deficient classification as a lower priority than endangered or critically endangered,” says Kolby, who was not affiliated with the new study. “And because of that, data deficient species don’t get a lot of conservation funding.”

Of course, the new study shows that data deficient species are often just as vulnerable as the more well-known ones.

González del Pliego says her team came to this conclusion by analysing which traits coincide with extinction risk for species that have already been listed—things like body size, range size, and geographic location. They then searched the IUCN’s list of data deficient amphibians for species that exhibited those traits. This led them to a whole new suite of creatures on the edge.

Filling in the gaps

Another important finding from the study was that certain places, like Central Africa and Southeast Asia, are conservation deserts for amphibian protection. In these areas, scientists and governments will need to create new conservation plans to target data deficient amphibians that aren’t likely to be saved beneath the umbrella of more well-known species.

“Fortunately, with our study we can now know where resources should be allocated and which species and regions to target first,” says González del Pliego.

Amphibians are some of the most poorly known and threatened animals on the planet, says Jodi Rowley, an amphibian biologist at the Australian Museum and National Geographic Explorer who was not involved in the new study. But she, too, sees reason for hope.

“We are at an exciting and pivotal time in history. We are in a race to discover what biodiversity we have on this remarkable planet,” says Rowley. “It's not too late to make the changes needed to ensure that most of these species are not lost forever.”

A new study finds that many amphibian species whose populations are classified as “data deficient” are likely threatened with extinction.

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