Is the Endangered Species List Missing Hundreds of Species of Birds?

A new study suggests the IUCN’s methods are underestimating the risks to many species, but the organization say the research is flawed

Wood Wren
A purplish-mantled tanager, a species the study suggests should be listed at vulnerable Natalia Ocampo-Peñuela

When researchers talk about endangered species, they are usually referring to plants and animals listed by the International Union for Conservation of Nature, the international body that keeps track of imperiled species around the globe. When research and science determines that a species is in trouble, the IUCN puts it on their Red List of Threatened Species, listing them as species of least concern, near vulnerable, vulnerable, endangered or critically endangered.

But Aviva Rutkin at New Scientist reports that a new study suggests the system the IUCN uses to classify endangered species is flawed, and based on the abundance of freely available geospatial data, hundreds of species should have their threat classification upgraded.

A team from ETH Zurich and Duke University led by Natalia Ocampo-Peñuela used this data to evaluate the risk level for 586 bird species. First they refined the habitat and elevation needs for the selected species from six bird-rich regions including Madagascar, southeast Asia, and Brazil. Then, using geospatial satellite data, they looked at the change in forest cover over time to determine how much habitat loss impacted those species.

They conclude in a paper published in the journal Science Advances that 43 percent or 210 of the birds they looked at are more vulnerable than their IUCN classification—eight species of these birds are currently listed as “least concern” but are actually critically endangered. For instance, Michael Price at Science reports that the IUCN lists the grey-winged cotinga, which lives at certain elevations in the mountains northeast of Rio de Janeiro, as having a 3,300-square-kilometer habitable range. But the satellite data shows that only about 100 square kilometers of suitable habitat still remain.

“The Red List employs rigorously objective criteria, is transparent, and democratic in soliciting comments on species decisions. That said, its methods are seriously outdated,” Duke conservation biologist Stuart Pimm, co-author of the study, says in a press release. He tells Price that the organization's reliance on old maps for its habitat data is imprecise, causing them to miss potential threats to the species. “We have powerful new tools at our fingertips, including vastly improved digital maps, regular global assessments of land use changes from satellite images and maps showing which areas of the planet are protected by national parks,” he says in the release.

Other scientists agree. “At the time the IUCN came up with the criteria, these sorts of technologies weren’t available,” Wesley Hochachka assistant director of bird population studies at the Cornell Lab of Ornithology tells Rutkin. “An approach like this one can help modernize the classification system, particularly for parts of the world where data on the ground is scarce. What the authors are doing, it’s almost like a plea for more data and more information to make even better and clearer and more accurate assessments of where species are living.”

The researchers believe that their finding probably extends to mammals and amphibians as well.

For their part, the IUCN disputes the study. Stuart Butchart, head of Birdlife International, the group overseeing the Red List’s birds, tells Angela Chen at The Verge that the paper is "fundamentally flawed." The study, Butchart says, uses a different set of metrics than the IUCN. The IUCN uses a broad habitat range while the study uses much narrower criteria. It’s like saying that the potential range for the American robin on the island of Manhattan is only Central Park, instead of the whole island, he points out. By only including only Central Park in the data, the paper exaggerates the endangered risk to the bird. “They are generating these results where they predict that we have underestimated extinction risk because they are looking at the wrong measure,” IUCN Senior Scientific Officer Michael Hoffman tells Chen.

Whatever the case, the study authors say the research highlights the need for the IUCN to embrace the new technologies available in conservation science. “What we do most carefully is to show that while IUCN’s assessments may be consistent, they fail to include readily available geospatial data that would greatly improve the accuracy of evaluations of a species’ risk of extinction,” they tell Rutkin. “We make specific suggestions on how IUCN could improve its guidelines for more consistent assessments.”

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