The ESA fails due to slow listing process

By Joshua Rapp Learn

The snail darter (Percina tanasi) is one of the most recent species to become delisted on the U.S. Endangered Species Act. Credit: U.S. Fish and Wildlife Service Headquarters

A new analysis on the population of species listed under the Endangered Species Act reveals shortcomings in the way that the United States manages at-risk wildlife.

The new study found that the average size of the populations of species at the time of listing in the past 30 years has not changed.

“One of the reasons for the relatively low number of species delisted due to recovery is because species are being listed after they reach very small population levels,” said Erich Eberhard, a PhD candidate at Columbia University and an author of the study.

According to the U.S. Fish and Wildlife Service, 2,367 species or subspecies have been listed under the U.S. Endangered Species Act. Some 1,672 are found in the U.S., as of Oct. 12, 2022. Since its inception, only 54 species have been delisted from the act due to recovery, while 56 species have been downgraded from endangered to threatened. Other species have been delisted due to extinction—the USFWS announced 23 extinctions in 2021.

“Delisting due to recoveries are quite low,” Eberhard said.

Eberhard and his colleagues wanted to see why the ESA was failing to protect many vulnerable species. One of Eberhard’s colleagues, David Wilcove of Princeton University, had conducted a study analyzing the population sizes of all the listed species at the time they became protected under the ESA. The Federal Register states population estimates in its listing decision announcements, and Wilcove and his colleagues rounded up all the species listed as threatened or endangered from 1985 to 1991 in a study published in 1993 in Conservation Biology.

For the new study, published yesterday in PLOS ONE, Wilcove, Eberhard and others recently repeated the 1993 study, rounding up the population estimates of species listed from 1992 to 2020. They compared the average population sizes between both studies at the times of listing and found that the median population size at the time of listing hasn’t changed.

“There was no statistical difference in the size of populations at time of listing for species [between the two study periods],” Eberhard said.

What’s the problem?

One of the main reasons for slow recovery, Eberhard said, is that authorities wait too long to list species. These low numbers make it more challenging to recover populations. The study showed that, on average, vertebrate species that were listed had only 1,075 individuals left, while invertebrates had only 999 remaining individuals. Plants had only 120 estimated individuals remaining when listed.

“We’re very slow to get the species the protections that they deserve,” Eberhard said.

Part of this is due to backlog. The number of listed species is going up, but so is the number of petitions for listing species. This has created a kind of traffic jam for species needing listing. At the same time, funding for protecting species hasn’t increased at a proportionate level.

The number of listed species has increased by more than 300% from 2010 to 2020. But federal funding has not risen in step. As a result, the funding per individual listed species dropped by about 50% per species compared to 1985.

One potential way to overcome these shortcomings would be to increase funding, or improve the mechanism and requirements for listing, though the researchers didn’t specifically look at how the problem might be improved in this study.

“If species were identified sooner—listed sooner with larger population sizes—we would hope to find faster recovery and a higher success rate of recovery,” Eberhard said.

Caroline Murphy, government relations manager for The Wildlife Society, said that one possible fix for the funding gap could happen via the passage of the Recovering America’s Wildlife Act, which has passed the House of Representatives and is currently awaiting a vote in the Senate.

“While the Endangered Species Act remains the best tool the federal government has to protect species from reaching the point of extinction, it is clear that inadequate funding has been the main obstacle to recovery and delisting,” Murphy said. “Through passage of the Recovering America’s Wildlife Act, states, tribes and the federal government will have much-needed resources to avoid future Endangered Species Act listings, and can work to revive populations that have long remained listed under the Act.”

Joshua LearnJoshua Rapp Learn is a science writer at The Wildlife Society. Contact him at jlearn@wildlife.org with any questions or comments about his article.

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