The Endangered Species Act: Summary, Impact, and Current Status

Peninsular Bighorn Sheep
Endangered peninsular bighorn sheep, photographed in Anza-Borrego Desert State Park, California. ChrisMR / Getty Images

The Endangered Species Act (ESA, or the Act) is the primary law aimed at conserving the ecosystems necessary to the survival of threatened and endangered species in the United States. The law also provides a framework for the conservation of those species, and was drafted in response to a declaration by then President Richard Nixon that further conservation efforts were required to prevent the extinction of species. 

Passed in 1973, the Act is administered by the Department of Interior (generally, endangered animals), the Department of Commerce (marine mammals), and the Department of Agriculture (plants). In addition, the United States Fish and Wildlife Service (FWS) plays a substantial role in recommending species designations based on a number of factors set forth in the Act. 

There have been a number of amendments to the Endangered Species Act over the years. Most recently, while some of the ESA’s protections were rolled back by the Trump administration, President Biden took steps to reconsider these changes in his first days in office.

Endangered Species Definition

Section 3 of the Endangered Species Act sets forth a number of definitions that are integral to operation and enforcement of the Act. In addition to defining what constitutes a threatened or endangered species, this portion of the legislation spells out the scope of a species’ critical habitat, which parties are subject to prohibitions under the Act, and what is considered a prohibited "take."

A Federally Endangered Black-footed Ferret on the Plains
A federally endangered black-footed ferret. kahj19 / Getty Images

Some key definitions stated in section 3 of the ESA include:

Conserve, Conserving, and Conservation

When used in the Endangered Species Act, the terms "conserve," "conserving," and "conservation" refer to use of all of the methods necessary to restore a species to the point that it no longer requires protection under the Act. Pursuant to section 3 of the ESA, this may include research, habitat acquisition and maintenance, and propagation — and can even extend to permitted takings under section 10.

Critical Habitat

Under the ESA, a threatened or endangered species’ critical habitat includes the areas within the species’ geographic region that have characteristics — physical or biological — that are essential to conservation of the species, and the management of which might necessitate special considerations or protection. Critical habitat also includes areas outside of where the species lives, if those areas are needed for the species to recover. 


While species is a common term with both biological and legal meaning, the ESA uses the term to describe species and subspecies of all plants and animals. This may include birds, insects, fish, reptiles, mammals, crustaceans, flowers, grasses, and trees. 

Endangered Species

To qualify as endangered under the ESA, a species must be at risk of extinction in all of — or a significant portion of — its geographic area. That said, insects classified by the Secretary of the Interior or the Secretary of Commerce as pests are not considered endangered if their protection would pose an overwhelming risk to humans.

Ocelot (Leopardus pardalis). Mark Newman / Getty Images

Threatened Species

In contrast to a species that’s already endangered, threatened species are those likely to become endangered within the foreseeable future. While endangered species are afforded full protection under the ESA, section 4(d) of the Act lets the listing agency decide the extent to which protections apply to threatened species. This means that the agency — like the FWS — can carefully tailor protections based on the unique needs of each species. 

While some species may be designated as threatened as a first step toward protection, others may be downgraded to threatened after they are designated endangered and their numbers have time to rebound. 


For purposes of the ESA, the term person is extremely broad and extends to corporations, partnerships, trusts, associations, and other private entities in addition to individuals. This also extends to officers, employees, and other instrumentalities of the federal government, state governments, and foreign governments. Likewise, "person" includes state, municipality, and political subdivisions of states and other entities that fall under the jurisdiction of the United States. 

Coachella Valley Fringe-toed Lizard (Uma inornata)
Coachella Valley fringe-toed lizard (Uma inornata). Design Pics / Jack Goldfarb / Getty Images


Among other directives, the Endangered Species Act prohibits people from taking any species without a permit. Though this can be a somewhat confusing term, the Act defines what constitutes a "take" to include harassing, harming, pursuing, hunting, shooting, wounding, killing, trapping, capturing, or collecting the species. Likewise, attempting to do any of these things is also included in the definition of a take as prohibited under the Act.

Harm is further defined as something that will actually kill or injure members of the species. For example, harm may exist where there is significant habitat modification or degradation that could kill or injure the wildlife by "significantly impairing" behavior that is considered essential — like breeding, feeding, or finding shelter.

Summary of the Law

The ESA is primarily implemented by the U.S. Fish and Wildlife Service, which maintains a list of endangered species in the U.S. and around the world, and the U.S. National Oceanic and Atmospheric Administration (NOAA) Fisheries Service, which focuses on marine species. These entities, in concert with federal agencies, are responsible for ensuring that authorized actions are consistent with the continued survival of listed species and the protection of their habitats.

Here are the major components — and mechanics — of the Endangered Species Act:

Determination of Endangered and Threatened Species

Anyone can petition the FWS to include a species on this list. That said, the decision to list a species as threatened or endangered must be based exclusively on its biological status and any threats to its survival. The determination is made — and action can be taken to protect a species — if one or more of five factors threaten its survival. This review must be based on the best available scientific information collected by scientists at the local, state, and national level. 

The five factors that must be considered are:

  • Whether a large portion of the species’ vital habitat has been damaged or destroyed.
  • The extent to which a species has been overutilized for commercial, recreational, scientific, or educational purposes.
  • Whether the species is threatened by disease or predation.
  • The inadequacy of existing protection afforded by current regulations and legislation.
  • Any natural or human-made factors that might impact continued survival of the species.

In addition to species that are ultimately listed as endangered or threatened, the ESA provides for a list of candidate species that is maintained by the U.S. Fish and Wildlife Service (FWS). These candidate species include those that meet at least one of the consideration criteria, but that are of lower priority than other species.

Grizzly reflections as it crosses pond in Yellowstone National Park
Grizzly bear in Yellowstone National Park. William Krumpelman / Getty Images


Sections 6, 7, and 8 of the Endangered Species Act cover state cooperation, interagency cooperation, and international cooperation, respectively. Generally, the secretary of the Interior and the secretary of Commerce must make every effort to cooperate with individual states — to the extent practicable. More specifically, this should involve consulting with relevant states before acquiring land or water as a means of conservation for a threatened or endangered species. 

Similarly, federal agencies must also consult with the secretary to make sure that any actions they’re considering won’t have a negative impact on a threatened or endangered species — or result in the destruction of, or damage to, its habitat. As with determinations under the Act, these consultations must be made with the help of the best commercial and scientific data possible. 

Prohibited Acts

Section 9 of the Endangered Species Act lists the actions that are prohibited under the legislation. Though there are some exceptions, the ESA generally prohibits importing, exporting, taking, possessing, selling, and transporting species that are designated as threatened or endangered. Taking is defined broadly to include harassing, harming, pursuing, hunting, shooting, wounding, killing, trapping, capturing, or collecting a listed species — or attempting to do so.

West Indian Manatee, Trichechus manatus latirostris, USA, Florida, FL, Crystal River
West Indian manatee, Trichechus manatus latirostris, in Florida. Reinhard Dirscherl / Getty Images


While prohibited activities under the ESA are extensive, they are subject to a number of exceptions for certain private activities. These exceptions are outlined in section 10 of the ESA, and mean that certain activities may be permitted through the FWS as long as they are consistent with conservation of the species in question. These are the three major permits issued by the FWS Ecological Services program:

  • Incidental take permit. This type of permit applies to non-federal entities that believe their activities may result in a take of an endangered or threatened species. For activities that are otherwise legal, an entity must submit an application for an incidental take permit, as well as a habitat conservation plan (HCP) that helps to minimize and mitigate the negative impacts of the activity. 
  • Enhancement of survival permit. These permits are reserved for non-federal landowners that are currently engaged in Safe Harbor Agreements or Candidate Conservation Agreements with Assurances. This type of permit enables and encourages landowners to take steps to protect a species with the understanding that they will not encounter further regulatory restrictions in response to those actions. 
  • Recovery and interstate commerce permit. Intended to facilitate valuable efforts to research and better understand the needs of listed species, recovery and interstate commerce permits allow certain activities that would otherwise be deemed a take — like transporting and selling listed species across state lines. 

Beyond the permitted exceptions above, the ESA’s prohibitions can be limited by exemptions approved by the Endangered Species Committee (ESC), also known as the "God Squad." Created by amendments to the ESA in the late 1970s, the ESC can exempt an agency from the need to evaluate potential actions, as is otherwise required under section 7(a)(2) of the Act, if certain determinations are made via a balancing test.

Also provided for in section 10 of the ESA, an experimental population is a special designation that can be applied to listed species before they are reestablished in an unoccupied area of the species’ range, or in some cases, outside its historical range. This designation lets the FWS customize take prohibitions for experimental populations. 

Penalties and Enforcement

Covered under section 11 of the Act, enforcement of the ESA is accomplished through a combination of citizen suits and civil and criminal penalties like imprisonment, fines, and forfeiture. First, any fish, wildlife or plants illegally taken, possessed, sold, or purchased under the Act may be confiscated. Penalties for a criminal violation may include imprisonment and a fine up to $50,000. In the case of a criminal conviction, the equipment and vehicles used in violation of the ESA can also be confiscated. 

While civil violations don’t carry risk of imprisonment, violators may be subject to hefty fines. Violation of major provisions come with a $25,000 fine for knowing violations and a $12,000 fine for all other violations. Civil violations of minor provisions, permits, or regulations come with a $500 fine per violation.

Endangered Species List

A portrait of a red wolf
Red wolf in Asheboro, North Carolina. Cavan Images / Getty Images

The endangered species list is an inventory of all of the species that are currently identified as either threatened or endangered under the ESA. This list, which is updated by the secretary of the Interior of the secretary of Commerce pursuant to the Act, also includes information about each species’ critical habitat as well as a description of the types of activities that might further damage that ecosystem. 

There are currently more than 1,600 species listed as threatened or endangered under the ESA, around 940 of which are plants. However, because populations change in response to pressures on habitats and other impacts, the number of plants and animals on the list can increase or decrease with new determinations. In fact, the list is reviewed every five years to determine whether any species should be upgraded to endangered, downgraded to threatened, or removed entirely. 

Some well-known animals on the endangered species list include:

  • Red wolf. After coming back from extinction in the wild in 1980, red wolves are currently endangered, with only between 10 and 20 wild wolves surviving in 2020. Historically found throughout the Eastern and South Central United States, the red wolf is now only present in the wild in experimental populations in portions of North Carolina and Tennessee.
  • West Indian manatee. Designated threatened in all locations it is found, the West Indian manatee is one of the most famous and charismatic species protected by the ESA. Originally designated as endangered in 1967 under the endangered Species Preservation Act (a precursor to the ESA), populations have rebounded to around 13,000 and the species was redesignated as threatened in 2017.
  • Ocelot. An endangered species wherever it’s found, the ocelot was originally listed in 1972. Since then, conservation efforts have included research, restoration of thorn forest habitats, and construction of wildlife crossings that can help them safely travel under roads. 

Has the ESA Worked?

Though the Endangered Species Act has undergone both expansions and limitations since its passage in 1973, the Act has successfully met its goal of protecting endangered and threatened species and their habitats. In fact, more than 99% of species that are protected by the ESA have escaped extinction. More specifically, it’s estimated that in the absence of the ESA, at least 227 species might have gone extinct since enactment of the legislation. 

Bald eagle flying over the Mississippi River. Todd Ryburn Photography / Getty Images

Some high-profile ESA success stories have included:

  • Bald eagle. Deemed endangered in most states under the ESA in 1978, bald eagles have since reached a population of more than 7,000 breeding pairs. This success was the result of a combination of efforts, including captive breeding programs and a ban on DDT.
  • Gray wolf. Gray wolves were originally designated as endangered under the ESA in 1974. In 1978, they were reclassified as threatened in every state except Minnesota. Ultimately, with more than 6,000 gray wolves in the lower 48 states, the species was delisted under the ESA in October 2020.
  • Grizzly bear. Following designation as threatened in 1975, grizzlies in the Greater Yellowstone Ecosystem were delisted in 2017 and management was transferred to Montana, Wyoming, and Idaho. Protected status was reinstituted in September 2018, and the population of grizzly bears in Yellowstone has now increased from just 136 in 1975 to around 728 in 2019.

Trump Environmental Rollbacks and the ESA

Based on a belief that the Endangered Species Act is too restrictive to businesses like developers and fossil fuel companies, the Trump administration took several steps to weaken protections under the Act. Some actions the Trump administration took that undermined the efficacy of the ESA include:

  • Revised methods for assessing the impact of pesticides on endangered species.
  • Narrowed the scope of "habitat" under the ESA to exclude areas that are necessary to ensure recovery of listed species over the long term.
  • Created a process for excluding areas of critical habitat, and developed a list of impacts to consider when evaluating whether to exclude an area.
  • Enabled federal agencies to conduct economic analyses when evaluating whether a species should be listed.
  • Reduced the northern spotted owl’s protected habitat by 3.4 million acres.

Biden Administration

The Biden administration took steps to reverse Trump’s rollbacks on its first day in office by asking federal agencies to review and consider overturning more than 100 of Trump’s policies, including those that weakened the ESA.

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