Endangered Species Act of 1973: Listings, Prohibitions, and Penalties

The Endangered Species Act of 1973 is the federal law that protects wildlife and plants at risk of extinction in the United States. It covers more than 1,600 species by making it illegal to harm listed animals or their habitat, requiring federal agencies to check whether their projects will push a species closer to extinction, funding recovery efforts, and giving private citizens the power to sue when the rules are ignored. Two agencies run it: the U.S. Fish and Wildlife Service for land and freshwater species, and the National Marine Fisheries Service for marine species and fish like salmon that move between salt and fresh water.¹

Who Gets Protected and How Species Are Listed

The Act sorts protected species into two categories. An endangered species is in danger of extinction throughout all or a significant portion of its range. A threatened species is likely to become endangered in the foreseeable future.² Endangered species get the strongest automatic protections. Threatened species get a more flexible set of rules that can be tailored to what the species actually needs.

A species qualifies for listing if any one of five statutory factors threatens its survival:³

Present or threatened destruction, shrinkage, or fragmentation of habitat.
Overuse for commercial, recreational, scientific, or educational purposes.
Disease or predation the population cannot withstand.
Inadequate existing laws or regulations.
Other natural or human-caused threats to the species’ continued existence.

Listing decisions rest entirely on biological evidence. Economic consequences of protecting a species play no role at the listing stage.

Anyone can petition the government to add or remove a species, but the petition has to present substantial scientific or commercial information showing the action may be warranted.⁴ From there the timeline is fixed. Within 90 days the agency issues a preliminary finding on whether the petition presents enough information to justify a full review. Within 12 months of receiving the petition, it must reach one of three conclusions: listing is not warranted, listing is warranted and a proposed rule will follow, or listing is warranted but precluded by higher-priority actions already underway.³ That third outcome leaves the species in a holding pattern; the agency has to keep monitoring, and petitioners can challenge the finding in court.

What the Law Forbids

The core prohibition is on “taking” a listed animal. The statute defines “take” broadly to cover harassing, harming, pursuing, hunting, shooting, wounding, killing, trapping, capturing, or collecting, and even the attempt counts.²

Federal regulations extend “harm” to include significant habitat modification that actually kills or injures wildlife by disrupting essential behaviors like breeding, feeding, or sheltering.⁵ That’s one of the most consequential rules in the Act. A landowner who clears a forest used for nesting by an endangered bird can violate the law without ever touching an animal.

The Act also bans importing, exporting, transporting in interstate or foreign commerce, and selling or offering to sell any endangered species. These trade restrictions apply whether or not the person knows the species is listed.⁶

These prohibitions apply automatically only to endangered species. For threatened species, the Fish and Wildlife Service uses what are called 4(d) rules to decide which protections apply. A species-specific 4(d) rule can tailor protections to the actual threats, while a blanket rule extends the full endangered-species protections.⁷ For a landowner or business, this is where the practical rules for a threatened species live.

Penalties for Violations

Consequences are steep. A knowing civil violation can bring penalties up to $25,000. Criminal violations carry fines up to $50,000, up to a year in prison, or both.⁸ Each individual animal harmed can count as a separate violation, so a single incident can multiply fast. Enforcement agents can also seize equipment, vehicles, and specimens used in or obtained through a violation.

How Federal Projects Are Reviewed

Every federal agency has to make sure any action it authorizes, funds, or carries out will not jeopardize a listed species or destroy or adversely modify designated critical habitat.⁹ In practice, an agency proposing a highway, issuing a development permit, or funding a dam has to consult with the Fish and Wildlife Service or the National Marine Fisheries Service before it can move ahead.

Formal consultation can run up to 90 days, during which the two agencies exchange information about the project and the species involved. The consulting agency then has 45 days to issue a biological opinion on whether the project would jeopardize the species or damage critical habitat.¹⁰ If the opinion finds jeopardy, it has to suggest reasonable and prudent alternatives the acting agency can adopt to comply with the law. The agency isn’t technically forced to take those alternatives, but it also cannot go forward with the original plan if that plan would cause jeopardy.

When the biological opinion finds no jeopardy but expects some incidental harm, it comes with an incidental take statement. That document sets out the expected impact, minimization measures, and conditions the agency must follow. As long as the agency stays within those conditions, the incidental take is not treated as a violation.⁹

What Private Landowners and Developers Need to Do

Section 7 consultation applies only to federal agencies. If you’re a private landowner, developer, or business planning an otherwise lawful activity that will incidentally harm a listed species, you need a separate authorization under Section 10, called an incidental take permit.¹¹

To get the permit, you submit a habitat conservation plan that spells out four things:

The likely impact of the activity on the species.
The steps you’ll take to minimize and mitigate that impact, plus how you’ll fund them.
The alternatives you considered and why you didn’t choose them.
Any additional measures the agency requires.

The agency issues the permit only after finding that the take will be truly incidental, that impacts will be minimized and mitigated to the maximum extent practicable, that funding is adequate, and that the taking will not appreciably reduce the species’ chances of surviving and recovering in the wild.¹¹ That last criterion is the tallest hurdle. If the project would tip the species closer to extinction, no amount of mitigation will get the permit through.

Once a permit is issued and the plan is being properly implemented, the “No Surprises” rule protects the permit holder. If unforeseen circumstances come up later, the government cannot demand additional mitigation or land restrictions beyond what the plan already requires.¹²

For non-federal landowners who want to help species voluntarily, the Fish and Wildlife Service in May 2024 merged two older programs, Candidate Conservation Agreements with Assurances and Safe Harbor Agreements, into a single program called Conservation Benefit Agreements.¹³ The trade is regulatory certainty in exchange for voluntary conservation. If a species covered by the agreement is later listed, the landowner gets a permit assuring that no additional measures will be imposed without consent.

Critical Habitat

When a species is listed, the government has to designate, to the maximum extent prudent and determinable, the geographic areas essential to its conservation.³ These are areas with the physical or biological features the species needs, such as specific soil types, nesting sites, or water conditions.

Unlike the listing decision, critical habitat designation does require the government to weigh economic impacts, national security, and other relevant factors. A specific area can be excluded if the benefits of leaving it out outweigh the conservation benefits of including it, with one hard limit: no exclusion is allowed if it would lead to the species’ extinction.

Critical habitat can also cover land the species doesn’t currently occupy but may need for recovery. Unoccupied areas qualify only when the occupied habitat alone isn’t enough to conserve the species, there’s a reasonable certainty the area will contribute to conservation, and it contains one or more of the essential physical or biological features.¹⁴

Recovery and Getting Off the List

The Act requires the government to develop and implement recovery plans. Each plan has to include site-specific management actions, objective criteria that would trigger delisting when met, and time and cost estimates.³ Priority goes to species most likely to benefit, especially those in conflict with development or economic activity. Plans go through public comment before they’re finalized.

The Fish and Wildlife Service also conducts periodic five-year reviews using the best available science. A review can recommend uplisting from threatened to endangered, downlisting from endangered to threatened, delisting entirely, or leaving the classification alone.¹⁵ A review is only a recommendation. Any actual status change requires a separate rulemaking with Federal Register publication, peer review, and public comment.

A species can be removed from the list for one of three reasons: it has recovered enough that it no longer needs protection, the original data supporting the listing turned out to be wrong, or the species has gone extinct. When delisting is based on recovery, the government must monitor the species for at least five years to confirm it stays healthy.¹⁶

Enforcement by Citizens

The Act gives private citizens their own enforcement tool. Any person can file a civil lawsuit to stop a violation of the Act by any party, including federal agencies. Citizens can also sue the Secretary of the Interior to compel non-discretionary duties the agency has failed to perform, such as processing a listing petition within the statutory deadlines.¹⁷

Before filing, the citizen has to give 60 days’ written notice to the alleged violator and to the Secretary. The suit cannot go forward if the government has already begun its own enforcement action or is diligently prosecuting a criminal case on the same violation. In an emergency posing a significant risk to a species, the lawsuit can be filed immediately after notice is given. Conservation organizations have used citizen suits heavily to force overdue listing decisions and challenge inadequate habitat designations.

State Cooperative Agreements

The federal government can enter into cooperative agreements with states that run adequate conservation programs of their own. To qualify, a state has to have the authority to conserve resident threatened and endangered species, conduct status investigations, acquire habitat, and allow public participation in listing decisions.¹⁸

States with cooperative agreements receive federal funding. The federal share covers up to 75 percent of program costs for a single state and up to 90 percent when two or more states collaborate on shared species. Those partnerships extend the Act’s reach well beyond what federal agencies could handle alone, especially for species whose habitat crosses state lines.

1
U.S. Fish & Wildlife Service. About Us
2
Office of the Law Revision Counsel. 16 USC 1532 – Definitions
3
Office of the Law Revision Counsel. 16 USC 1533 – Determination of Endangered Species and Threatened Species
4
U.S. Fish & Wildlife Service. The Petition Process
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eCFR. 50 CFR 17.3 – Definitions
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Office of the Law Revision Counsel. 16 USC 1538 – Prohibited Acts
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U.S. Fish & Wildlife Service. Section 4(d) Rules – Frequently Asked Questions
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U.S. Fish & Wildlife Service. Section 11 – Penalties and Enforcement
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Office of the Law Revision Counsel. 16 USC 1536 – Interagency Cooperation
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U.S. Fish & Wildlife Service. ESA Section 7 Consultation
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Office of the Law Revision Counsel. 16 USC 1539 – Exceptions
12
NOAA Fisheries. Permits for the Incidental Taking of Endangered and Threatened Species
13
U.S. Fish & Wildlife Service. Candidate Conservation Agreements with Assurances
14
U.S. Fish & Wildlife Service. Critical Habitat
15
U.S. Fish & Wildlife Service. Five-Year Status Reviews
16
NOAA Fisheries. Delisting Species Under the Endangered Species Act
17
Office of the Law Revision Counsel. 16 USC 1540 – Penalties and Enforcement
18
Office of the Law Revision Counsel. 16 USC 1535 – Cooperation with States