The United States has one of the world's most powerful legal tools for protecting species at risk of extinction: the Endangered Species Act. Since it was passed by Congress in 1973 (on the heels of a 1967 precursor law), the Act has built up a stellar success rate, saving 99% of species it protects from extinction.

The Endangered Species Act turns 50 years old in 2023. All year long, we'll be sharing actions you can take to help this landmark law save imperiled animals and plants. Learn more and take action now.


Three vital provisions give the Act its teeth. It’s “citizen-suit” provision lets public-interest groups and individuals petition and sue sluggish federal agencies to make sure the Act protects species as it was intended to. Meanwhile its critical habitat provision — often enforced via the citizen-suit provision — requires those agencies to protect lands and waters species need to survive and recover. And finally, the Act’s consultation provision requires federal agencies to avoid jeopardizing protected species or “adversely modifying” — that is, damaging — their critical habitat in all actions they fund, permit, or carry out.

Although the Act works by protecting individual species or subspecies, at its best it provides landscape-level protection for complements of species and their ecosystems.

So far the Act has helped bald eaglesblack-footed ferrets, gray whales, California condors and Mexican gray wolves, among hundreds of other species whose status has improved dramatically under its protection.

More than 1,600 animals and plants are protected, or “listed,” as endangered or threatened in the United States. But there are hundreds more waiting for protection under this crucial law. Unfortunately the process used to list species by the U.S. Fish and Wildlife Service — the agency that’s mostly in charge of carrying out the Act, with a few ocean species covered by another agency called NOAA Fisheries — has been too slow, on average taking 12 years to protect species even though, by law, it’s only supposed to take two.



When the Center suspects that a species needs Endangered Species Act protection, our scientists study the species to check — and to determine whether it needs “threatened” or the more protective “endangered” status. (Endangered species are plants and animals so rare they’re in danger of becoming extinct; threatened species are plants and animals likely to become endangered within the foreseeable future throughout all or a significant portion of their range.)

If our research confirms the species needs protection, we compile our data in a petition asking the Fish and Wildlife Service for terrestrial species, or NOAA Fisheries for marine species, to move forward on protection.

Legally the federal government has one year to respond to our petition with a finding that the species may warrant protection or doesn’t warrant protection. If it finds the former, the agency has another year to propose protection, which it must then finalize within another year.

If the agency decides the species doesn’t warrant protection — well, if that decision contradicts what science tells us about the species’ imperilment, the Center will probably sue to challenge it. We’ll also probably sue if the agency takes too long to respond to our petition. (Before we sue, we usually file a “notice of intent to sue” as a warning, which sometimes prompts action on its own.)

Once a species is listed, the Fish and Wildlife Service or NOAA Fisheries is required to consult with other federal agencies to ensure that any action they fund, permit, or carry out doesn’t jeopardize the species or its habitat.

Critical Habitat and Recovery Plans

When an agency lists a species, the Endangered Species Act requires it to designate critical habitat at the same time, as well as to draft a recovery plan, which is a roadmap outlining actions to be taken to help the species recover and, eventually, thrive in the wild.

As with listing species, the designation of critical habitat usually requires litigation — the federal government rarely takes this step on its own. And it often doesn’t designate enough critical habitat to do the job, requiring even more litigation from the Center.

State Protection

In addition to the U.S. Endangered Species Act., which protects species federally, many states have their own versions of an endangered species law, upheld by state wildlife-management agencies. State listing works differently from federal listing, and state laws are often weaker than their federal counterpart. California, though, has a very strong Endangered Species Act, giving species certain interim protections as soon as listing is proposed.


The Center leads the country in the number of species we’ve protected under the Endangered Species Act through petitions, lawsuits and negotiation. Learn more about some of the species we work to save.

The Act: A Wild Success

We also advocate for the Endangered Species Act itself by showcasing its incredible power via reports assessing its efficacy on the state level, regionally — like in the U.S. Northeast — and nationwide.

Capping two years of research, our 2004 study Extinction and the Endangered Species Act identified all 108 species who went extinct or missing in the first 21 years of the Act. The number — 108 — is shockingly high, but it shows a grave failure in federal management of the Act rather than a failure of the Act itself.

Numerous later studies made that even more clear. To objectively test whether the Act was recovering species at a sufficient rate, our 2012 report On Time, On Target compared the actual recovery rate of 110 species with the projected recovery rate in their federal recovery plans, finding 90% of species recovering as specified by the plans. And our 2016 report A Wild Success found that the Act has been extraordinarily successful in recovering birds in particular: Under its protection 85% of bird populations in the continental United States increased or stabilized, and the average population increase was 624%.

We continue to work on systematic assessments of the Act's performance.

Defending the Act

Meanwhile the Endangered Species Act periodically comes under heavy fire from industry-backed interests in Washington, where — according to the ebb and flow of lobbying influence in Congress and the White House — politicians are pressured to deauthorize or substantially weaken the Act. This happens most often in obscure, backdoor ways driven by vested interests, since the Act enjoys widespread popular support and is therefore difficult to attack directly.

The Center has played a central role over the years in fending off these insidious assaults. Sometimes that’s by supplying policymakers with the scientific data they need to effectively defend the Act from ill-informed detractors, and sometimes it’s by filing legal petitions and lawsuits.

And our close watchdogging of the Fish and Wildlife Service has brought official corruption to light and, by exposing bureaucratic wrongdoing, catalyzed a large-scale reevaluation of unsound decisions that would hurt species.

Pergrine falcon photo courtesy Wikimedia Commons/Dennis Jarvis