How Are Animals Added to the Endangered Species List?

A wildlife policy expert at Cummings School of Veterinary Medicine explains what factors are considered when listing a species as threatened or endangered in the U.S.  

When the U.S. Endangered Species Act (ESA) was signed into law in 1973, more than 100 species were listed as endangered or threatened. Today, there are more than 700 animals and 900 plant species listed by the U.S. Fish and Wildlife Service (USFWS).

Tufts Center for Animals and Public Policy director Allen Rutberg, a behavioral ecologist and urban wildlife specialist, spent 10 years working with the Endangered Species Coalition as a senior scientist for wildlife protection at the Humane Society of the United States before landing at Cummings School of Veterinary Medicine.

“Endangered species issues are interesting to students and important to talk about,” said Rutberg, who dedicates two lectures in his course, Animals & Society, per semester to the topic. “The Endangered Species Act has been described as the strongest wildlife protection statute in the world. It has been an effective law, but also a controversial one because it’s remarkably inflexible in terms of its language.”

There are two ways for any species to be added to the list, he said. First, the Fish and Wildlife Service or the National Marine Fisheries Service may decide to add a species to the list based on their own research. The second way allows an individual or organization to petition for a species to be added.

In either case, there is a series of steps written into the ESA which both government agencies and individual citizens must follow, including the collection of data to prove a species’ worthiness of being included on the list.

“There’s no allowance for economic impact or politics or anything like that the way the law is written. If the data shows that the species is in trouble, it needs to be listed,” Rutberg said.

Five factors are considered when determining if a species needs ESA protection:

  • the decline of a species’ habitat
  • over-utilization of the species
  • disease impacting the species
  • impact of inadequate existing regulatory mechanisms
  • other factors, manmade or natural, that could impact its existence

“Endangered is at risk of extinction and threatened is at risk of being endangered, so it’s a lower threshold for threatened,” Rutberg explained. “There’s a little bit of subjectivity involved, but the agencies look at population estimates and trends—if there are dramatic declines in the species or habitat—and at the nature of the threats. What’s causing these population declines? The agencies identify those threats and look at whether and how a listing on the act would mitigate or end those threats.”

Exceptions to the Rule

Even with the most compelling data, listing for some species may be delayed or blocked due to implications for industry and development. Take the greater sage grouse, for instance. The grazing bird calls the Intermountain West its home, an area popular for cattle farming and energy production. Adding the bird to the Endangered Species List could have significant economic impact on both energy and cattle farming, so Western landowners and energy companies, as well as state and federal governments, negotiated a compromise in 2015 that kept the bird off the list.

A greater sage grouse on a grazing area

In 2015, Western landowners, energy companies, and state and federal governments negotiated a compromise that kept the greater sage grouse off the endangered species list. Photo: Tom Reichner / Shutterstock

The compromise required the landowners and energy companies to protect key bird habitats, and the government agreed not to list the bird as endangered. The bird’s close relative, the Gunnison sage grouse, was listed as threatened in December 2014 and is only found in southwestern Colorado and a small portion of Utah.

National and International Impacts of the ESA

Although the ESA was created to protect species within the United States, it also supports the conservation of species outside of the country and allows the national enforcement of the Convention on International Trade in Endangered Species. This treaty limits trade in protected wildlife across U.S. borders when commercial activity could harm listed species.

To help protect threatened species outside the U.S., agencies and organizations can send funding and expertise to support conservation in other parts of the world, Rutberg said. This may be the case for species such as African and Asian elephants, which are protected under the ESA. This helps the USFWS restrict trade in elephant parts, like tusks, and contribute to the fight against poaching and illegal trade.

Jumbo statue at Tufts University
Photo: Alonso Nichols / Tufts University

Did You Know?

Tufts’ affinity for elephants goes beyond the Jumbo mascot. Allen Rutberg is the co-director of Jumbos for Jumbos: Tufts Elephant Conservation Alliance (TECA), which aims to advance elephant conservation through trans-disciplinary research, scholarship, outreach and teaching.

Here in the U.S., Rutberg wants people to know that the law has worked. It has protected many species and kept them alive. But there’s more work to be done, he said.

“Not a lot of species have left the list, and part of that is because of the limited power of the act to protect ecosystems. It’s not holding back the tide of development,” Rutberg said. “We probably need a more comprehensive approach to environmental protection than this provides. But for what it is, it has worked really well focusing public attention on charismatic species that need help, and they do become surrogates for their ecosystems.”

The Battle Over the Gray Wolf

The gray wolf, a species which was included for protection on the original list in 1967, was delisted in 2020 after the federal government cited a “successful recovery” of the species. But in February 2022, after a court battle, it was relisted as endangered in 44 of the contiguous 48 United States, excluding states that border the Northern Rocky Mountains.

“There have been a couple of thousand wolves killed since they were taken off the list in Idaho, Wyoming, and Montana,” Rutberg said. “Populations in some of those states are now plummeting. And so, the question is, did the federal government act too soon to take them off the list? Or are they going to become endangered again under state wildlife management?”

The conversation goes beyond preserving species and ecosystems. Rutberg believes there are politics at play that are impacting the preservation of the species.

“In theory, under state wildlife management, [the states] should be protecting the species,” Rutberg said. “Essentially wolves have become a proxy species for the red-blue polarization. Wolf supporters are perceived as blue, and the wolf management laws being passed by the red state legislatures in Idaho, Montana, and Wyoming seem almost vindictive. There is now a petition to return them to endangered species protection.”

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