The Endangered Species Act: Overview and
March 4, 2021
Implementation
Pervaze A. Sheikh
The Endangered Species Act of 1973 (ESA; P.L. 93-205, 87 Stat. 884, 16 U.S.C. §§1531-1544)
Specialist in Natural
aims to conserve species listed as endangered or threatened under the act. Under the ESA, it is
Resources Policy
the policy of Congress that all federal agencies shall seek to conserve threatened and endangered

species, use their authorities in furtherance of the ESA, and cooperate with state and local
Erin H. Ward
agencies to resolve water resource issues in concert with conserving endangered species. The
Legislative Attorney
ESA is administered by the U.S. Fish and Wildlife Service (FWS) and the National M arine

Fisheries Service (NMFS). Under the ESA, domestic and foreign species of animals (both
vertebrate and invertebrate) and plants can be listed as either endangered or threatened, according
R. Eliot Crafton
to an assessment of the risk of their extinction. Once a species is listed, the act provides tools to
Analyst in Natural
aid the species’ conservation and recovery and to protect its habitat.
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The ESA and its predecessors have been in place since 1966. Since enactment, these acts have

led to the listing of over 2,400 species as threatened or endangered. As of October 2020, 2,363
species were listed, the majority of which (71%) were listed in the United States; the remaining
29% were foreign species. Of all listed species in October 2020, 79% were endangered and 21% were threatened. As of
October 2020, 91 species had been delisted under the ESA since it was enacted in 1973, which is approximately 3.7% of the
total number of species ever listed under the act.
Many Members of Congress are interested in how the ESA is implemented , because states—as well as American Samoa,
Guam, the Northern Mariana Islands, Puerto Rico, the Virgin Islands, outlying Islands in the Pacific and the Caribbean, and
Washington, DC—have species that are, or may be in the future, listed under the act. Congress also is interested in broader
issues surrounding the ESA and oversight of its implementation, primarily because some stakeholders perceive the ESA as, at
times, pitting economic development against the conservation of listed species.
This report discusses selected provisions of the ESA and selected federal regulations that implement the ESA. It discusses
several major provisions of the act, generally in the order they appear in the U.S. Code. These sections include Section 4, on
listing species under the ESA; Section 6, on cooperating with states in recovering listed species; Section 7, on interagency
cooperation and consultation; Section 9, on prohibitions under the ESA; Section 10, on exceptions to prohibitions; Section
11, on penalties and enforcement under the ESA; and Section 8, on the implementation of the Convention on International
Trade in Endangered Species of Wild Fauna and Flora (CITES), among others.
The ESA has been amended numerous times since its enactment. The authorization for funding included in Section 15 of the
ESA expired on October 1, 1992; nevertheless, Congress has appropriated funds in each succeeding fiscal year, and the
ESA’s provisions—including those related to listings, consultations, prohibitions, and penalties—remain in effect.
A long-standing question related to the ESA is whether it effectively achieves its purposes, as outlined in the act. Various
stakeholders have put forth different interpretations on this issue. Some stakeholders have offered, as evidence of the ESA’s
success, the very low rate of extinction for those species listed under the act. Other stakeholders have suggested the ESA has
been ineffective at conservation, noting that recovery is an integral component of success as presumed by the definition of
conservation included within the act—“to bring any endangered or threatened species to the point at which the measures
provided in [the ESA] are no longer necessary”; to support this position, they highlight that only a small number of species
have been delisted due to recovery.
In addition to addressing whether the ESA has been successful at conserving species, stakeholders have raised other issues
related to the act. These issues include, among others, the ESA’s effects on private property and landowners; the ability to
conserve species before it is necessary to list them; the cost of listing species and the resulting economic impacts; the
availability of funding for the ESA; incentives for conservation under the ESA; the states’ role in conserving listed species;
delays in listing, delisting, and reclassifying species under the ESA; and litigation related to the ESA. Given the perennial
nature of these issues and the ESA’s controversial nature, these matters are routinely of concern to Members of Congress.
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Introduction
The Endangered Species Act of 1973 (ESA; P.L. 93-205, 87 Stat. 884, 16 U.S.C. §§1531-1544)
aims to conserve species listed as endangered or threatened under the act. The stated purpose of
the ESA is to
Provide a means whereby the ecosystems upon which endangered species and threatened
species depend may be conserved, to provide a program for the conservation of such
endangered species and threatened species, and to take such steps as may be appropriate to
achieve the purposes of the treaties and conventions set forth in subsection (a) of this
section.1
Under the ESA, it is the policy of Congress that al federal agencies shal seek to conserve
threatened and endangered species, use their authorities in furtherance of the ESA, and cooperate
with state and local agencies to resolve water resource issues in concert with conserving
endangered species.2
The ESA is administered by the U.S. Fish and Wildlife Service (FWS) for terrestrial and
freshwater species,3 as delegated by the Secretary of the Interior, and by the National Marine
Fisheries Service (NMFS) for marine and anadromous species,4 as delegated by the Secretary of
Commerce (hereinafter, FWS and NMFS are jointly referenced as the Services).5 Under the ESA,
domestic and foreign species of animals (both vertebrate and invertebrate) and plants can be listed
as either endangered or threatened, according to an assessment of the risk of their extinction (see
Figure 1.)6 Once a species is listed, the act provides tools to aid its conservation and recovery and
to protect its habitat. Among these tools are the ESA’s prohibition of take (e.g., kil ing, capturing,
or harming) of endangered species without a permit and its requirement that federal agencies, in
consultation with FWS or NMFS, as applicable, ensure their actions are not likely to jeopardize
the continued existence of listed species or to result in destruction or adverse modification of
designated critical habitat.
The ESA extends to both domestic and foreign species. As of October 2020, a total of 2,363
species of animals and plants were listed as either endangered or threatened; 1,668 of al listed
species occur in the United States and its territories,7 and the remainder (695 species) occur solely
in other countries.8 (See Figure 1.) Regulations under the ESA for foreign species largely address

1 Endangered Species Act (ESA; P.L. 93-205, 87 Stat. 884, 16 U.S.C. §§1531-1544) §2, 16 U.S.C. §1531(b).
2 ESA §2(c), 16 U.S.C. §1531(c).
3 For detailed information on the U.S. Fish and Wildlife Service (FWS) program for endangered and threatened species,
see FWS, “ Endangered Species,” at http://www.fws.gov/endangered/.
4 T he National Marine Fisheries Service (NMFS), a part of the National Oceanic and Atmospheric Administration
(NOAA), is also sometimes referred to as NOAA Fisheries. Fish are anadrom ous if they spend most of their lives in salt
water and then swim up a river to spawn. Young anadromo us fish hatch and then swim downstream to grow to
adulthood in the ocean. For example, most salmon and some sturgeon species are anadromous.
5 In addition to the administrative responsibilities assigned to the Secretary of the Interior and the Secretary of
Commerce, the Secretary of Agriculture, pursuant to 16 U.S.C. §1532(15), is responsible for administering the ESA
with regard to the import and export of listed plant species.
6 Domestic species are those species found in the United States, regardless of whether they are also found elsewhere.
Foreign species are species that are not native to the United States and therefore only found abroad.
7 Listings attributed to the United States include species with populations where the United States shares jurisdiction
with another nation.
8 For updated information, see FWS, “Environmental Conservation Online System (ECOS) – Listed Species
Summary,” at https://ecos.fws.gov/ecp/report/boxscore.
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import restrictions and domestic breeding activities within the United States; the ESA general y
does not regulate listed species outside the United States and U.S. territories, because these
species are beyond U.S. jurisdiction. For example, the ESA does not prohibit individuals from
kil ing listed species in foreign countries.9
The ESA was passed in 1973, but it was preceded by laws for the preservation and conservation
of endangered species in 1966 and 1969. The Endangered Species Preservation Act (P.L. 89-669),
enacted in 1966, implemented a process for listing native species that were considered
endangered and a program for conserving, protecting, restoring, and propagating those species.
For example, the Endangered Species Preservation Act authorized the Secretary of the Interior to
acquire land as needed to further the conservation of listed species. The first list of endangered
species was promulgated in 1967 and included 78 species, including the grizzly bear, American
al igator, and bald eagle, among others.10
In 1969, the Endangered Species Conservation Act (P.L. 91-135) amended the Endangered
Species Preservation Act. The Endangered Species Conservation Act provided, among other
things, a list of species in danger of worldwide extinction and expanded protections for species
already listed. The act also cal ed for an international convention or treaty to conserve endangered
species; the United Nations (U.N.) made a similar resolution in 1963.11 This U.N. resolution laid
the groundwork for a multilateral treaty known as the Convention on International Trade in
Endangered Species of Wild Fauna and Flora (CITES). (See section on “CITES” for more
information.)
In 1973, Congress passed the Endangered Species Act to provide for the conservation of
threatened and endangered species.12 The ESA has been amended on numerous occasions since it
was enacted.13 The authorization for funding included in Section 15 of the ESA expired on
October 1, 1992;14 nevertheless, Congress has appropriated funds in each succeeding fiscal year,
and the ESA’s provisions—including those related to listings, consultations, prohibitions, and
penalties—remain in effect.

9 Any person seeking to hunt such species would be subject only to the laws and regulations of the country where the
species resides. However, the ESA can limit a hunter’s ability to bring back to the United States (i.e., import) any
trophy from such a hunt. For example, individuals are required to obtain appropriate permits prior to importing a trophy
of an ESA-listed species—such as a lion (Panthera leo leo) or an African elephant (Loxodonta africana)—and certain
restrictions apply on how many such trophies can be imported into the United States.
10 Department of the Interior (DOI), “Native Fish and Wildlife: Endangered Species,” 32 Federal Register 4001 (March
11, 1967).
11 International Union for Conservation of Nature, Resolution on Illegal Traffic in Wildlife Species, GA 1963 RES 005,
1963 Nairobi General Assembly, 1963.
12 Congress passed the Endangered Species Act pursuant to its authority under the Commerce Clause to “regulate
Commerce with foreign Nations, and among the several States, and with Indian tribes.” U.S. Const. art. I, §8, cl. 3.
Every U.S. Court of Appeals to consider the issue has upheld Congress’s authority to regulate listed species under that
clause, including with respect to species located only in on e state. See People for the Ethical T reatment of Property
Owners v. U.S. Fish & Wildlife Serv., 852 F.3d 990, 999 -1008 (10th Cir. 2017) (“ Every one of our sister circuits that
has addressed this issue has agreed that regulation of purely intrastate species is an essential part of the ESA’s
regulatory scheme.”); San Luis & Delta-Mendota Water Auth. v. Salazar, 638 F.3d 1163, 1174-77 (9th Cir. 2011); Ala.-
T ombigbee Rivers Coal. v. Kempthorne, 477 F.3d 1250, 1274 (11th Cir. 2007); GDF Realty Invs. v. Norton, 3 26 F.3d
622, 640 (5th Cir. 2003); Rancho Viejo, LLC v. Norton, 323 F.3d 1062, 1080 (D.C. Cir. 2003); Gibbs v. Babbitt, 214
F.3d 483, 487 (4th Cir. 2000).
13 T he ESA has been amended several times, notably by P.L. 94-359 (1976); P.L. 95-212 (1977) P.L. 95-632 (1978);
P.L. 96-159 (1979); P.L. 96-246 (1980); P.L. 97-79 (1981); P.L. 97-304 (1982); P.L. 98-327 (1984); P.L. 99-659
(1986); P.L. 100-478 (1988); P.L. 100-707 (1988); and P.L. 108-136 (2003).
14 16 U.S.C. §1542.
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Figure 1. Distribution of Species Listed Under the Endangered Species Act (ESA), as
of October 2020

Source: Congressional Research Service (CRS), from data provided by the U.S. Fish and Wildlife Service (FWS),
October 2020.
Notes: Three foreign plant species and 692 foreign animal species are listed under the Endangered Species Act
(ESA; P.L. 93-205, 87 Stat. 884, 16 U.S.C. §§1531-1544).
Congressional debate over the ESA has addressed a variety of issues. These issues include the
law’s purpose and structure as a whole, specific species and their status and regulation under the
law (e.g., gray wolves)15, and specific activities and how those activities affect listed species (e.g.,
the effect of water conveyance and pumping in the confluence of the Sacramento and San Joaquin
Rivers’ Delta on the threatened Delta smelt). Many Members of Congress have expressed interest
in how the ESA is implemented, because states—as wel as American Samoa, Guam, the
Northern Mariana Islands,16 Puerto Rico, the Virgin Islands, outlying Islands in the Pacific and

15 For more information on the gray wolf, see CRS Report R46184, The Gray Wolf Under the Endangered Species Act
(ESA): A Case Study in Listing and Delisting Challenges, by Erin H. Ward.
16 16 U.S.C. §1532(17) and 50 C.F.R. §81.1(i) both define state in the context of the ESA to be “any of the several
States, the District of Columbia, the Commonwealth of Puerto Rico, American Samoa, the Virgin Islands, Guam, and
the T rust T erritory of the Pacific Islands.” However, the T rust T erritory of the Pacific I slands has since terminated, and
of the trustees, only the Commonwealth of the Northern Mariana Islands (CNMI) is still in political union with the
United States. For more information, see 48 U.S.C. §1681 and 48 U.S.C. §§1801 et seq. T he covenant between t he
United States and the CNMI, which established the political union ( P.L. 94-241, as amended), provided for the
applicability of the ESA to the CNMI.
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the Caribbean, and Washington, DC—have species that are, or may be in the future, listed under
the act.17 Some Members have supported efforts to amend the ESA to increase the authorization
of funding for the act, particularly to address the backlog of species the Services have determined
warrant listing and to improve recovery efforts; to focus efforts under the act more on species
recovery rather than primarily on protection; to elevate the role of states in implementing the act;
and to provide increased regulatory certainty to landowners to incentivize conservation activities,
among other things.18 Some other Members may share the sentiment of reauthorizing the ESA but
may have other priorities, such as increasing appropriations for implementing the ESA.19
Congress also may be interested in broader issues surrounding the ESA and oversight of the act’s
implementation, primarily because some stakeholders perceive the ESA and the conservation of
listed species, at times, as an obstacle to economic development.20 For example, some see the
ESA as a primary driver of or exacerbating factor in resource controversies. Examples of resource
controversies where the ESA may be a factor include the al ocation of water supplies through the
Central Val ey Project in California and the conservation of threatened Delta smelt (Hypomesus
transpacificus), listed under the ESA, and Northwest timber harvests, which balance logging,
recreation, and sport fishing with ecosystem protection and the conservation of listed species,
such as the northern spotted owl (Strix occidentalis caurina). In contrast, some stakeholders argue
the ESA is not a primary factor in resource controversies and may be one of several factors
contributing to such issues.21
This report discusses selected provisions of the ESA and selected federal regulations that
implement the ESA. The discussion is not comprehensive. It includes references to other CRS
products that provide in-depth discussion of some provisions.
Key Provisions of the ESA Addressed in This Report
This report discusses several major provisions of the ESA. It addresses the following sections of
the act, general y in the order they appear in the U.S. Code.22

17 For an accounting of the number of species listed as threatened or endangered by state, see FWS, Environmental
Conservation Online System (ECOS), “ Listed Species Believed to or Known to Occur in Each State,” at
https://ecos.fws.gov/ecp/report/species-listings-by-state-totals?statusCategory=Listed. In addition to the federal ESA,
many states have enacted endangered species acts (though the naming of these acts may differ) to list and conserve
species under state law. When discussing the ESA or listed species in this report, only the federal ESA is being
referenced.
18 For example, see statement of Sen. John Barrasso, U.S. Congress, Senate Committee on Environment and Public
Works, Modernizing the Endangered Species Act: Legislative Hearing on S.4589, the Endangered Species Act
Am endm ents of 2020, 116th Cong., 2nd sess., September 23, 2020.
19 For example, see statement of Sen. T homas R. Carper, U.S. Congress, Senate Committee on Environment and Public
Works, Modernizing the Endangered Species Act: Legislative Hearing on S.4589, the Endangered Species Act
Am endm ents of 2020, 116th Cong., 2nd sess., September 23, 2020.
20 For example, see A. J. Hoffman, M. H. Bazerman, and S. L. Yaffee, “Balancing Business Interests and Endangered
Species Protection,” MIT Sloan Management Review, vol. 39, no. 1 (Fall 1997), pp. 59-73.
21 T he timing and amount of water diverted for agricultural and municipal needs in the Central Valley of California is a
complex issue that involves several factors, including listed species under the ESA. Scientists argue the issue is not
derived solely from the ESA but also involves water quality factors, toxins, lawsuits, and water supply, among other
factors. See Committee on Sustainable Water and Environmental Management in the California Bay -Delta, Sustainable
Water and Environm ental Managem ent in the California Bay-Delta, National Research Council, 2012.
22 Section 2 of the ESA (16 U.S.C. §1531), which addresses congressional findings and declaration of purposes and
policy, is discussed briefly in the “ Introduction” to this report. For more information on legal aspects of the ESA,
namely the listing process, please see CRS Report R46184, The Gray Wolf Under the Endangered Species Act (ESA): A
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 Section 3: Definitions
 Section 4: Listing
 Section 5: Land Acquisition
 Section 6: Cooperation with States
 Section 7: Interagency Cooperation and Consultation
 Section 9: Prohibitions
 Section 10: Exceptions
 Section 11: Penalties and Enforcement
 Section 8: Convention Implementation
 Section 15: Authorization of Appropriations
Additional relevant definitions and implementing regulations are discussed in the applicable
sections.
ESA Section 3: Definitions
Section 3 of the ESA defines terms for purposes of the act.23 Selected definitions from the ESA
are discussed below. Other definitions under the ESA are discussed later in this report, where they
are most relevant.
Conserve, Conserving, and Conservation
The terms conserve, conserving, and conservation mean to use and the use of al methods and
actions to bring an endangered or threatened species to the point where the protections of and
measures within the ESA are no longer necessary for the species. The definition states that these
methods and measures include activities associated with scientific resources management (e.g.,
research, census, law enforcement, habitat acquisition and maintenance, propagation,
transplanting, and, in limited circumstances, regulated taking).24
Endangered Species
The term endangered species refers to those species—as defined by the ESA—that are “in danger
of extinction throughout al or a significant portion of its range.” Although the definition of
species includes animals (both vertebrates and invertebrates) and plants, the definition of
endangered species precludes listing certain insect species determined by the Secretary of the
Interior or the Secretary of Commerce, as appropriate, to be pests.25

Case Study in Listing and Delisting Challenges, by Erin H. Ward.
23 ESA §3, 16 U.S.C. §1532.
24 ESA §3(3), 16 U.S.C. §1532(3).
25 ESA §3(6), 16 U.S.C. §1532(6). In this report, references to the Secretary are to the Secretary of the Interior or the
Secretary of Commerce, as appropriate, unless otherwise stated. See “ Secretary” for more information.
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Fish or Wildlife
The term fish or wildlife refers to any member of the animal kingdom, including mammals, fish,
birds, amphibians, reptiles, mollusks, crustacean, arthropod, or other invertebrates (e.g., insects
such as the rusty patched bumble bee [Bombus affinis] and the American burying beetle
[Nicrophorus americanus]). It “includes any part, product, egg, or offspring thereof, or the dead
body or parts thereof.”26
Secretary
In the ESA, the term the Secretary means the Secretary of the Interior or the Secretary of
Commerce, as appropriate, except that it also could refer to the Secretary of Agriculture with
respect to enforcement provisions in the act and CITES as they relate to terrestrial plants (al
references to Secretary in this report are to the Secretary of the Interior or the Secretary of
Commerce, as appropriate, unless otherwise stated).27
The Secretary of the Interior, through FWS, general y manages and administers the ESA with
regard to terrestrial, freshwater, and catadromous species.28 However, marine and anadromous
species general y are the responsibility of the Secretary of Commerce, acting through NMFS.
Management of marine mammals under the ESA is split between the Services,29 and sea turtles
are managed jointly by both Services.30 The law assigns several key roles to the Secretary of the
Interior and provides for the relationship of the Secretary of the Interior and the Secretary of
Commerce and their respective powers. For example, the Secretary of the Interior is responsible
for listing and delisting species. In the case of species administered by NMFS, the Secretary of
Commerce conveys listing, reclassification, and delisting determinations to the Secretary of the
Interior. Per the ESA, the Secretary of the Interior is instructed to list or uplist (i.e., reclassify a
species from being listed as threatened to being listed as endangered) a species under the
Secretary of Commerce’s purview after being informed of such determination by the Secretary of
Commerce. Downlisting (i.e., reclassifying a species from being listed as endangered to being
listed as threatened) and delisting determinations for species managed by NMFS are implemented
if the Secretary of the Interior concurs with the Secretary of Commerce’s recommendation.31
Species
The ESA defines species to include any subspecies of fish, wildlife, or plant and any distinct
population segment (DPS) of vertebrate fish or wildlife species that interbreeds when mature.32
Accordingly, the Secretary can list a species (as used in taxonomy; i.e., Genus species), a
subspecies (i.e., Genus species subspecies), or a DPS as a “species” under the act. The Secretary

26 ESA §3(8), 16 U.S.C. §1532(8).
27 ESA §3(15), 16 U.S.C. §1532(15).
28 Fish are catadromous if they are born in salt water, migrate to fresh water to mature, and then migrate back to salt
water to spawn. T he American eel (Anguilla rostrate) can be catadromous, though the species also can remain in
marine or brackish water during maturation.
29 For more information, see FWS, International Affairs, “ Marine Mammals,” at https://www.fws.gov/international/
animals/marine-mammals.html.
30 50 C.F.R. §17.11.
31 ESA §(2)(a)(2)(C), 16 U.S.C. §1533(a)(2)(C).
32 A distinct population segment (DPS) under the ESA refers to a population of a species that is a discrete and
significant segment of the species as a whole.
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cannot, however, list a group of organisms that does not qualify as one of these three categories.
The term DPS is specific to the act rather than borrowed from biology or taxonomy. It has been
interpreted by the Services in guidance and in rules promulgated under the ESA, as described in
the text box on Distinct Population Segments.
Take
The ESA defines the term take to mean “to harass, harm, pursue, hunt, shoot, wound, kil , trap,
capture, or collect, or to attempt to engage in any such conduct.”33 FWS defined the terms harass
and harm for species under its management through regulation at 50 C.F.R. §17.3, and NMFS
similarly defined harm through regulation at 50 C.F.R. §222.102. The Services both define harm
to include significant habitat modification or degradation that kil s or injures wildlife. A group of
landholders and parties with interests in forestry chal enged FWS’s inclusion of modification or
degradation of habitat as an overly expansive interpretation of the statute.34 The parties argued
that harm should be limited to using force directly against a species.35 The Supreme Court held
that it was reasonable for the Secretary to interpret harm to include habitat modification or
degradation that results in actual injury or death of a listed species.36
Threatened Species
The term threatened species means any species, as defined by the ESA, that is likely to become
an endangered species within the foreseeable future (see text box below on “Foreseeable Future
in Regulations”) throughout al or a significant portion of its range.37
Foreseeable Future in Regulations
The FWS and the NMFS defined the term foreseeable future in regulations for the first time in a final rule
promulgated in August 2019 (84 Federal Register 45020). Before this rule, the Services had interpreted the
foreseeable future on a case-by-case basis in the course of promulgating listing rules for particular species and for
purposes of related litigation.
Under the final rule, the Services define foreseeable future as extending “only so far into the future as the Services
can reasonably determine that both the future threats and the species’ responses to those threats are likely.” The
Services explain that likely means more likely than not. Although the final rule provides a definition for the term
foreseeable future, the Services stated they stil would determine how this definition applies to a particular species
on a case-by-case basis based on the best available data. The Services stated they intend to take into account life-
history characteristics, threat-projection time frames, and environmental variability to determine how foreseeable
future applies for a given species.
The Services and certain stakeholders have characterized the definition as general y codifying the Services’ existing
practices when determining the foreseeable future in listing decisions. Other stakeholders have expressed
concerns that this definition of foreseeable future would limit consideration of long-term projected threats,
including from climate change (e.g., habitat changes or sea-level rise) and could limit the use of population
modeling to evaluate the fate of a species under future conditions. The Services wil have discretion to evaluate
these and other factors when considering which threats and responses are likely in implementing this definition.
Sources: 50 C.F.R. §424.11(d). Rebecca Barho and Brooke Wahlberg, “Expert Analysis ESA Rule Changes Less
Drastic Than Critics Claim,” Law360 (August 29, 2019), at https://www.law360.com/transportation/articles/
1192657/esa-rule-changes-less-drastic-than-critics-claim; Jake Li, “Last Week’s Endangered Species Regulations:

33 ESA §3(19), 16 U.S.C. §1532(19).
34 Babbitt v. Sweet Home Chapter of Communities for a Great Oregon, 515 U.S. 687, 692-93 (1995). Hereinafter
referred to as “Sweet Home,” 1995.
35 “Sweet Home,” 1995 at 697-98.
36 “Sweet Home,” 1995 at 697-704.
37 ESA §3(20), 16 U.S.C. §1532(20).
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What Real y Happened?” Environmental Policy and Innovation Center, August 20, 2019, at
http://policyinnovation.org/the-real-story-on-the-new-endangered-species-act-rules/.
Note: For more information on listing species under the Endangered Species Act (ESA; P.L. 93-205, 87 Stat. 884,
16 U.S.C. §§1531-1544) due to climate change, see CRS Report R45926, The Endangered Species Act and Climate
Change: Selected Legal Issues, by Linda Tsang.
ESA Section 4: Listing, Critical Habitat, and
Recovery
The Services may list a species as endangered or threatened under the ESA pursuant to Section 4
of the act and the accompanying regulations.38 Under the ESA, they may also reclassify species
through uplisting or downlisting, or delist them.
Criteria and Factors for Listing
The Services may list a species as endangered or threatened if one or more ESA factors would
render the species in danger of extinction (endangered) or likely to become so in the foreseeable
future (threatened) in al or a significant portion of its range.39 The ESA factors are
1. The present or threatened destruction, modification, or curtailment of the species’
habitat or range
2. The species’ overuse for commercial, recreational, scientific, or educational
purposes
3. Disease or predation affecting the species
4. Inadequate existing regulatory mechanisms protecting the species
5. Other natural or man-made factors affecting the species’ continued existence40
The ESA addresses both anthropogenic and natural factors that could affect a species’ viability.
For example, a dwindling species subject to natural stressors could be listed under the ESA
pursuant to the third factor. However, a species’ smal population alone may not necessarily
warrant its listing. Courts have held that the Services may need to weigh other considerations,
such as the reasons for the smal population size, if and the rate at which population size is
changing, and the potential implications of smal population size on the species’ risk of
extinction.41 If the Secretary determines a species is threatened or endangered based on any ESA
factor, the Secretary is required to list the species.42
The ESA provides for listing species, subspecies, or, for vertebrate fish and wildlife, distinct
population segments (DPS). Typical y, a DPS is described in geographic terms (e.g., the Northern
Rocky Mountain DPS for gray wolves, Canis lupis). Depending on how a species is listed, ESA
protections for fish and wildlife species may extend to (1) the species as a whole, including al
subspecies, if the taxonomic species is listed; (2) the subspecies, if the subspecies is listed; or (3)

38 ESA §4, 16 U.S.C. §1533.
39 ESA §3(6), (20), 16 U.S.C. §1532(6), (20).
40 ESA §4(a)(1), 16 U.S.C. §1533(a)(1).
41 See, for example, Ctr. for Biological Diversity v. Zinke, 900 F.3d 1053, 1073 -74 (9th Cir. 2018); Sw. Ctr. for
Biological Diversity v. Norton, Civ. Action No. 98-934, 2002 WL 1733618, at *13 (D D.C. July 29, 2002).
42 ESA §4(a)(1), 16 U.S.C. §1533(a)(1).
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an identified population of the taxonomic species or subspecies when a DPS is listed. Protections
also may differ depending on whether a species is listed as endangered or threatened (see
“Section 4(d) Rule”). More limited protections are available for plants (see “Section 9:
Prohibitions”).43 The ESA does not protect organisms considered neither animal nor plant (e.g.,
Eubacteria, archaea, and viruses).
Distinct Population Segments
Under the ESA, a distinct population segment (DPS) refers to a vertebrate fish or wildlife population that is a discrete
and significant segment of a species as a whole. (16 U.S.C. §1532(16)). For purposes of this discussion, species
refers to a taxonomic species rather than a species as defined by the ESA. Discreteness is based on the
population’s separation from other populations of the species and may be “the consequence of physical,
physiological, ecological, or behavioral factors.” The Services evaluate significance based on biological and
ecological factors. To be designated significant, the Services consider factors that include, but are not limited to,
the fol owing:

The DPS exists in an ecological setting that is unusual or unique for the species.

Evidence exists that loss of the DPS would lead to a gap in the species’ range.

Evidence exists that the DPS represents the species’ only surviving natural population, regardless of whether
the species is abundant outside its historic range as an introduced population.

The DPS is genetical y different from the species’ other populations.
By listing, reclassifying, or delisting a DPS, the Services can identify and either heighten or lower protections for a
distinct population of a species based on the best available science. For example, when a species is listed as
threatened, a portion of the species identified as a DPS may be listed as endangered while the rest of the taxon
remains threatened. In this way, the Services can use a DPS to address a species’ decline in a distinct region when
listing the entire species is unwarranted. In their policy, the Services have noted that identifying a DPS might
enable less costly protection and recovery measures than adopting measures across the species’ ful geographic
range. Alternatively, a DPS may be listed as threatened when the remainder of the species is listed as endangered,
or the Services may list a DPS as threatened or endangered and not list the remainder of the species.
Congress first included DPS as part of the ESA species definition in 1978. Prior to 1978, the ESA included “any
other group of fish or wildlife of the same species or smal er taxa in common spatial arrangement that interbreed
when mature” as part of the ESA species definition. In 1996, the Services promulgated a policy describing how
they would evaluate whether a population qualified as a DPS.
NMFS developed the concept of evolutionarily significant units (ESUs) as a way to interpret the “distinct population
segment” language in Section 3(16) of the ESA for Pacific salmon. ESUs general y include multiple (often as many as
20 to 30) populations or stocks and are intended to identify groups of salmon populations that can be listed as
threatened or endangered under the ESA. NMFS’s policy states that to qualify as an ESU, a stock must be
reproductively isolated from other population units and must represent a genetical y important or significant
component of the species. The ESU policy does not impose specific scientific criteria and applies only to Pacific
salmon population segments. Whether hatchery fish may be assigned to an ESU, thereby augmenting an ESU’s
population count, has been particularly controversial. For example, see CRS Report R40169, Endangered Species
Act Litigation Regarding Columbia Basin Salmon and Steelhead, by Stephen P. Mul igan and Harold F. Upton.
Sources: FWS and NMFS, “Policy Regarding the Recognition of Distinct Vertebrate Population Segment s Under
the Endangered Species Act,” 61 Federal Register 4722-4725, February 7, 1996; NMFS, “Policy on Applying the
Definition of Species Under the Endangered Species Act to Pacific Salmon,” 56 Federal Register 58612, November
20, 1991; D. S. Pennock and W. W. Dimmick, “Critique of the Evolutionarily Significant Unit as a Definition for
Distinct Population Segments Under the U.S. Endangered Species Act,” Conservation Biology, v. 11 (1997), pp. 611-
619.
The Services’ interpretation of “al or a significant portion of its range” has changed over time,
general y in response to adverse court decisions overturning listing rules.44 In 2014, the Services

43 ESA §9(a)(2), 16 U.S.C. §1538(a)(2).
44 See, for example, Defs. of Wildlife v. Norton, 258 F.3d 1136, 1141-42 (9th Cir. 2001); Defs. of Wildlife v. Salazar,
729 F. Supp. 2d 1207, 1217-28 (D. Mont. 2010).
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issued a joint policy interpreting “al or a significant portion of its range.”45 Under the policy, the
Services interpret the phrase as providing two independent bases for listing a species: (1) when
the species is endangered or threatened in al of its range or (2) when the species is endangered or
threatened across a significant portion of its range.46 The Services interpret the range of a species
to mean the area that the species currently occupies, not its historical range;47 at least one court
has upheld this interpretation as reasonable.48 The Services have, however, accounted for lost
historical range when evaluating the factors threatening a species.49
The 2014 policy also explained how the Services would determine whether a portion of a species’
range was significant, but district courts have since overturned that definition.50 Under the policy,
the Services considered a portion of a species’ range to be significant if “the species is not
currently endangered or threatened throughout its range, but the portion’s contribution to the
viability of the species is so important that, without the members in that portion, the species
would be in danger of extinction, or likely to become so in the foreseeable future, throughout al
of its range.”51 District courts invalidated this interpretation, because they concluded it rendered
the phrase “a significant portion of its range” superfluous.52 The courts reasoned that if a species
would be endangered or threatened in the areas outside the “significant portion” of the range and
the species is endangered or threatened within the significant portion of the range, then the
species is necessarily endangered or threatened throughout its entire range.53 The Services
therefore could never list a species as endangered or threatened in a significant portion of its
range under their interpretation—the species would always need to be endangered or threatened
in al of its range to be listed. The courts concluded that the Services used this interpretation to
give the phrase “a significant portion of its range” “as little substantive effect as possible,” which
was “arguably at odds with the conservation purposes of the ESA,” and that the Services
impermissibly limited the phrase “to situations in which it is unnecessary.”54
In a 2019 proposed rule to delist the gray wolf, FWS acknowledged that the Services’
interpretation of the term significant in the policy no longer applies.55 FWS proposed to identify
any portion of a species’ range “that could be significant under any reasonable definition of
‘significant’ that relates to the conservation of the [species proposed for listing].”56 The Services

45 FWS and NOAA, “Final Policy on Interpretation of the Phrase ‘Significant Portion of Its Range’ in the Endangered
Species Act’s Definitions of ‘Endangered Species’ and ‘T hreatened Species’”; Final Rule, 79 Federal Register 37578-
37612, July 1, 2014.
46 79 Federal Register 37580; see also 77 Federal Register 55530 and 55601, September 10, 2012.
47 79 Federal Register 37583-37585.
48 See, for example, Humane Soc’y of U.S. v. Zinke, 865 F.3d 85, 603-04 (D.C. Cir. 2017).
49 See, for example, 84 Federal Register 9648 and 9658, March 15, 2019.
50 Desert Survivors v. U.S. Dep’t of the Interior, No. 16-cv-01165-JCS, at *7 (N.D. Cal. Aug. 24, 2018) (issuing
nationwide injunction vacating and setting aside definition of “significant” under Services policy). See also Desert
Survivors v. U.S. Dep’t of the Interior, 321 F. Supp. 3d 1011, 1073 -74 (N.D. Cal. 2018) (order granting summary
judgment to plaintiffs); Ctr. for Biological Diversity v. Jewell, 248 F. Supp. 3d 946, 956 (D. Ariz. 2017).
51 79 Federal Register at 37579.
52 Ctr. for Biological Diversity, 248 F. Supp. 3d at 956; Desert Survivors, 321 F. Supp. 3d at 1073-74.
53 Ctr. for Biological Diversity, 248 F. Supp. 3d at 956; see also Desert Survivors, 321 F. Supp. 3d at 1073-74 (order
granting summary judgment to plaintiffs).
54 Ctr. for Biological Diversity, 248 F. Supp. 3d at 958.
55 84 Federal Register 9648 and 9684, March 15, 2019.
56 84 Federal Register 9684, March 15, 2019.
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have not yet revised their policy to interpret the term significant to account for the court’s
decision.
Using the Best Available Science
Pursuant to statutory requirements, the Secretary must decide whether to list species based only
on the best available scientific and commercial data, using information to which the agency has
access and information obtained from the public through the agency rulemaking process.57 The
statute does not define the phrase “best available scientific and commercial data,” and the
Services have not interpreted this phrase through regulation. Courts, however, have reviewed the
use of science and data in ESA decisions. One court held that the statutory phrase does not
require, and hence a court cannot order, the Services to conduct additional studies to obtain
missing data and that the agency must rely on inconclusive or uncertain information if that is the
best data available at the time of a listing decision.58 However, the agency cannot rely on data
that its own scientists agree is inaccurate.59 The relevant agency cannot ignore available
biological information or commercial data, especial y if that information is the most current or is
scientifical y superior to other information.60
A court also said that “the ‘best scientific and commercial data available’ is not a standard of
absolute certainty, and [is] a fact that reflects Congress’ intent that the FWS take conservation
measures before a species is ‘conclusively’ headed for extinction.”61 The fact that the studies on
which the Services rely are imperfect—so long as they are not inaccurate—does not undermine
those authorities as the best scientific data available; “the Service must utilize the best scientific
... data available, not the best scientific data possible.”62
The ESA expressly requires the Services to make listing determinations “solely on the basis of the
best scientific and commercial data available.”63 Congress added the word solely in the 1982
amendments to the ESA to clarify that the determination of endangered or threatened status was
intended to be made without reference to its potential economic impacts.64 In discussing the
addition of the word solely, a committee report stated the word is “intended to remove from the
process of the listing or delisting of species any factor not related to the biological status of the
species.”65 The committee further stated that it “strongly believes that economic considerations

57 ESA §4(b)(1)(A), 16 U.S.C. §1534(b)(1)(A). Formally, this determination is made by the Secretary of the Interior,
but for species under NMFS’s jurisdiction, the determination to list, delist, or change the status of a species cannot be
made without “prior favorable determination ... by the Secretary of Commerce.” 16 U.S.C. §1533(a)(2)(C).
58 Sw. Ctr. for Biological Diversity v. Babbitt , 215 F.3d 58 (D.C. Cir. 2000); see also Las Vegas v. Lujan, 891 F.2d
927, 933 (D.C. Cir. 1989); Defs. of Wildlife v. Jewell, 176 F. Supp. 3d 975, 999-1000 (D. Mont. 2016).
59 Ctr. for Biological Diversity v. Lohn, 296 F. Supp. 2d 1223 n.13 (W.D. Wash. 2003), vacated on other grounds by
Ctr. for Biological Diversity v. Lohn, 511 F.3d 960 (9 th Cir. 2007).
60 Am. Wildlands v. Kempt horne, 530 F.3d 991, 998 (D.C. Cir. 2008); Sw. Ctr. for Biological Diversity v. Babbitt , 926
F. Supp. 920, 927 (D. Ariz. 1996); Las Vegas, 891 F.2d at 933.
61 Defs. of Wildlife v. Babbitt, 958 F. Supp. 670, 679-80 (D.D.C. 1997); see also Defs. of Wildlife, 176 F. Supp. 3d at
999-1000.
62 Bldg. Indus. Ass’n of Superior Cal. v. Norton, 247 F.3d 1241, 1246-67 (D.C. Cir. 2001), cert. denied 534 U.S. 1108;
see also San Luis & Delta-Mendota Water Auth. v. Jewell, 747 F.3d 581, 602 (9 th Cir. 2014); Defs. of Wildlife, 176 F.
Supp. 3d at 999-1000 (emphasis added).
63 ESA §4(b)(1)(A), 16 U.S.C. §1533(b)(1)(A) (emphasis added).
64 P.L. 97-304, 96 Stat. 1411.
65 H.Rept. 97-567, pp. 19-20. T he conference report (H.Rept. 97-835, p. 19) also confirms that it was the intent of both
chambers that economic factors would not play a role in the listing of species for protection.
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have no relevance to determinations regarding the [listing] status of species,” and that applying
economic criteria to the listing process is prohibited by the inclusion of the word solely in the
legislation.66
As part of a listing decision, the Secretary may not consider the economic effects that listing may
have, such as delaying or modifying building projects in the area where the species occurs.67 In a
2019 final rule, the Services amended the regulations implementing listing decisions under the
ESA to no longer prohibit referencing the estimated economic costs of listing a species in the
listing decision. While acknowledging that economic costs cannot be a factor in whether to list a
species, the rule states that these costs can be reported in the listing decision to provide
transparency to stakeholders and be used for planning purposes.68
In summary, under the ESA, whether a species is endangered or threatened is a scientific decision
that the Services make based on the best available scientific and commercial data. Once a species
is listed as threatened or endangered, the Services must consider economics for critical habitat
designations and may consider economic factors when suggesting reasonable and prudent
alternatives.69
Process for Listing a Species
Listing a species, as wel as delisting or reclassifying (i.e., uplisting or downlisting), may be
initiated by the Services or through a petition process. The listing process is outlined by statute
and further specified in implementing regulations.70 This section discusses the process for listing
a species under the ESA (see Figure 2).

66 H.Rept. 97-567, pp. 19-20.
67 However, economic considerations, among other factors, are to be incorporated into critical habitat determinations.
ESA §4(b)(2), 16 U.S.C. §1533(b)(2). In addition to economic considerations, the ESA requires consideration of “ the
impact on national security, and any other relevant impact, of specifying any particular area as critical habitat .”
68 FWS and NOAA, “Endangered and T hreatened Wildlife and Plants: Regulations for Listing Species and Designating
Critical Habitat,” 84 Federal Register 45020-45053, August 27, 2019.
69 Reasonable and prudent alternatives refer to alternative actions that can be implemented consistent with the intended
purpose of the action and authority and jurisdiction of the action agency; is economically and technologically feasible;
and that the Services believe will avoid the likelihood of jeopardizing the continued existence of listed species or result
in the destruction or adverse modification of its critical habitat. 50 C.F.R. §402.02. See section on “ESA Section 7:
Interagency Consultation” for more information.
70 ESA §4, 16 U.S.C. §1533, and 50 C.F.R. §424.
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Figure 2. Listing Process Under the ESA

Source: Adapted from FWS, Endangered Species Program, “Listing a Species as a Threatened or Endangered
Species, August 2016, at https://www.fws.gov/endangered/esa-library/pdf/listing.pdf.
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Service-Initiated Listings
As delegated by the Secretaries, the Services, on their own initiative, may propose to list a species
under the ESA. When considering listing a species, the Services conduct status surveys to assess
the species’ viability. The process for Service-initiated reclassification is discussed in “Delisting,
Uplisting, and Downlisting,” below.
Petitions to List Species
Any person may petition the Services to list a species under the ESA.71 Person is defined under
the ESA as
an individual, corporation, partnership, trust, association, or any other private entity; or any
officer, employee, agent, department, or instrumentality of the Federal Government, of any
State, municipality, or political subdivision of a State, or of any foreign government; any
State, municipality, or political subdivision of a State; or any other entity subject to the
jurisdiction of the United States.72
Any person also may petition for a species to be reclassified or delisted.
The ESA requires that, within 90 days of receiving a petition to list a species, “to the maximum
extent practicable,” the Secretary make an initial determination as to “whether the petition
presents substantial scientific or commercial information” to indicate the requested action “may
be warranted.”73 If the relevant Service determines the petition may be warranted, the agency
conducts a status review of the species pursuant to the criteria for listing a species. The Service
has 12 months after receiving the petition to conduct the status review and make a final
determination on whether the petitioned action is warranted.
Lawsuits for Failing to Meet Listing Deadlines
Petitioners have sued the Services for failing to meet the 90-day and 12-month deadlines, particularly as the
number of petitions has increased. (See section on “Citizen Suits,” below.) Courts have rejected the argument
that the 90-day deadline establishes a “mandatory, nondiscretionary duty” for the Services, determining instead
that the phrase “to the maximum extent practicable” al ows for “at least a ‘limited exception’” to that time limit.
How much discretion this language affords has been a point of dispute between plaintiffs and the Services, with
courts general y deferring to the agency’s explanation for its al ocation of resources—provided it is reasonable.
Courts have held, however, that the 12-month statutory deadline is mandatory.
Although the 12-month deadline is statutorily required, the Services frequently have missed this deadline. In
February 2020, a stakeholder filed a lawsuit al eging the Services had missed the 12-month deadline for petitions to
list 231 species.
Before the court reaches a final determination on addressing deadlines for listing, the Services and parties may use
voluntary settlements to agree to alternative time frames for addressing petitions or listing species. For example,
several of these lawsuits were settled in 2011, setting deadlines for listing determinations on hundreds of species.
Sources: Biodiversity Legal Found. v. Babbitt, 146 F.3d 1249, 1253-57 (10th Cir. 1998); see also Inst. for Wildlife
Prot. v. Norton, 303 F. Supp. 2d 1175, 1177-78 (W.D. Wash. 2003); Ctr. for Biological Diversity v. Norton, 208 F.
Supp. 2d 1044, 1049 (N.D. Cal. 2002); Ctr. for Biological Diversity v. Norton, 254 F.3d 833, 837 (9th Cir. 2001);
Friends of Animals v. Salazar, 670 F. Supp. 2d 7, 12-13 (D.D.C. 2009); Biodiversity Legal Found. v. Norton, 180 F.
Supp. 2d 7, 9 (D.D.C. 2001); FWS, “Improving ESA Implementation: Listing Workplan Overview,” at
https://www.fws.gov/endangered/improving_ESA/listing_workplan.html.

71 ESA §4(b)(3), 16 U.S.C. §1533(b)(3).
72 ESA §3(13), 16 U.S.C. §1532(13).
73 ESA §4(b)(3)(A), 416 U.S.C. §1533(b)(3)(A).
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In May 2019, FWS issued a National Listing Workplan to prioritize its listing and critical habitat
designations over a five-year period.74 Through the workplan, which FWS intended to update
regularly, FWS aims to provide stakeholders with greater clarity and predictability about the
timing of listing determinations in order to encourage proactive conservation actions that may
avoid the need for federal protection. The workplan includes nearly 250 species.75
The status review for listing a species results in one of three findings: (1) the petitioned action is
not warranted; (2) the petitioned action is warranted and a listing proposal wil be promptly
published; or (3) the petitioned action is warranted but precluded by higher-priority species for
listing.76 If the Secretary concludes the action is warranted, the Service prepares a proposed rule
to list the species. The Services also may consider petitions for multiple species that share a
common ecosystem.
If a species is proposed for listing under the ESA, the Secretary must do the following:
 Publish the proposed regulation in the Federal Register and solicit public
comments over a 60-day comment period
 Seek independent peer review and scientific analysis from species specialists
 Give notice to state agencies and counties where the species is thought to occur
and invite those governments to submit comments on the proposal
 Give notice, if practical, to foreign countries where the species occurs or whose
citizens harvest the species on the high seas
 Notify relevant professional societies
 Publish a summary of the regulation local y where the species is found
 Upon request, hold a public hearing77
Alternatively, a warranted but precluded finding means the Services wil not propose to list the
species at that time and the species instead becomes a candidate species (see “Candidate Species
and Their Conservation” for more information).78 The ESA requires the Services to reevaluate
candidate species annual y until a listing rule is proposed or a not warranted finding is made. (See
Figure 2.)
Rulemaking
The Services initiate an Administrative Procedure Act (APA) rulemaking to list a species.79 To
issue a new rule (e.g., a listing rule) under the APA, the Services must publish notice of the
proposed rule in the Federal Register, provide a period for the public to comment on the

74 FWS, National Listing Workplan, May 2019, at https://www.fws.gov/endangered/esa-library/pdf/5-
Year%20Listing%20Workplan%20May%20Version.pdf .
75 FWS, National Listing Workplan, May 2019, at https://www.fws.gov/endangered/esa-library/pdf/5-
Year%20Listing%20Workplan%20May%20Version.pdf .
76 ESA §4(b)(3), 16 U.S.C. §1533(b)(3).
77 ESA §4(b)(5), 16 U.S.C. §1533(b)(5).
78 See “Candidate Species and T heir Conservation” section in this report.
79 5 U.S.C. §§551 et seq.
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proposed rule and submit data, and publish the final rule with an explanation of its basis and
purpose.80 The Services also may al ow for public hearings on the proposed rule.81
A species is listed, reclassified, or delisted through a final rule published in the Federal Register.
In accordance with the Services’ regulations, the rule must contain a summary of comments and
recommendations received in response to the proposed rule, summaries of the data on which the
rule is based, the relationship of the data to the final rule, and a summary of the factors affecting
the species, among other things.82 If a state agency submits comments disagreeing with a
proposed rule and the Secretary finalizes the rule in conflict with state comments, then the
Secretary is to provide the state agency with a justification for adopting a rule not consistent with
state comments.83
Candidate Species and Their Conservation
A candidate species is “any species being considered by the Secretary for listing as an
endangered or threatened species, but not yet the subject of a proposed rule.”84 FWS elaborates on
this definition by stating that candidate species are those for which the relevant Service has
sufficient information to propose the species as threatened or endangered, but developing a
proposal for listing is precluded by other, higher-priority listing activities, often referred to as
warranted but precluded.85 As noted, candidate species may result from either a Service-initiated
review of a species or the petition process. Candidate species have no statutory protection. The
status of candidate species must be reviewed annual y until one of the Services issues a proposed
rule for listing the species or the Services determine that listing is no longer warranted.
While a species is a candidate for listing, federal agencies and other entities may undertake
strategic activities to improve its status to avoid a listing proposal at some future date. For
example, federal agencies may develop a candidate conservation agreement with FWS or NMFS
to take specified actions to conserve a species.86 Nonfederal landowners may pursue a candidate
conservation agreement with assurances (CCAA).87 Under a CCAA, a landowner may agree to
carry out certain actions intended to conserve the species, with the assurance that, as long as the
agreed actions are carried out, the landowner wil not be required to change those activities if any
candidate species covered by the CCAA is subsequently listed as threatened or endangered.
According to FWS, early conservation of candidate species general y increases management
options and flexibility for landowners, lowers the cost of recovery for the species, and reduces the
likelihood that more restrictive land use measures wil be necessary in the future (i.e., if the
species continues to decline and is listed).88

80 5 U.S.C. §553.
81 5 U.S.C. §553.
82 50 C.F.R. §424.18.
83 50 C.F.R. §424.18(c).
84 50 C.F.R. §424.02(b).
85 FWS, “ Candidate Species: Section 4 of the Endangered Species Act ,” October 2017. Hereinafter cited as FWS,
“Candidate Species.”
86 For a library of policies concerning candidate conservation, see FWS, “Endangered Species Act Document Library,”
at https://www.fws.gov/endangered/esa-library/index.html#cc_policy.
87 See CRS Report R44592, Sage-Grouse Conservation: Background and Issues, by M. Lynne Corn, Katie Hoover, and
Carol Hardy Vincent , for an example of the use of candidate conservation agreement s and candidate conservation
agreement s with assurances in the conservation of a species.
88 FWS, “Candidate Species.”
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The Secretary must monitor the status of a candidate species and, if any emergency poses a
significant risk to the wel -being of the species, promptly list it.89 Some steps in the normal listing
process may be skipped for these emergency listings.
Section 4(d) Rules
Section 4(d) al ows the Secretary to extend certain protections that apply to endangered species to
threatened species. The act protects endangered species by prohibiting certain acts that may affect
them (see “ESA Section 9: Prohibitions”). For example, no person may import, export, sel , or
take (e.g., harm, hunt, harass, kil ) an endangered species. However, those protections are not
automatical y extended to threatened species in statute. Instead, Section 4(d) of the ESA
authorizes the Secretary to promulgate special regulations “as he deems necessary and advisable”
to conserve threatened species.90 Rules issued pursuant to this authority are known as 4(d) rules
or, alternatively, as special rules or species-specific rules. In a 4(d) rule, the Secretary may
prohibit nearly any act on a threatened species prohibited by ESA Section 9(a)(1) or (a)(2) for an
endangered species. Accordingly, protections for a particular threatened species can be tailored to
promote the conservation of the species and target specific threats to the species. Under the ESA,
the Services are not statutorily required to promulgate a 4(d) rule for every threatened species.
Historical y, the two Services have taken different approaches to extending prohibitions to
threatened species. In 1975, FWS promulgated a regulation known as the blanket 4(d) rule, which
extended nearly al of the prohibitions provided for wildlife species listed as endangered to
wildlife species listed as threatened, unless the Service promulgated a species-specific 4(d) rule; a
similar rule for plants was issued in 1977.91 These blanket 4(d) rules historical y provided de
facto protections to FWS-listed threatened species, unless a species-specific 4(d) rule superseded
the blanket rule for that species. NMFS never established a blanket 4(d) rule and has extended
prohibitions to threatened species on a case-by-case basis through species-specific 4(d) rules.
Without the blanket 4(d) rule, there are no de facto protections for NMFS-listed threatened
species without species-specific 4(d) rules.
In August 2019, FWS modified its regulations to no longer employ the blanket 4(d) rule for
species listed as threatened after the revised regulation became effective on September 26, 2019.92
Beginning September 27, 2019, species newly listed or reclassified as threatened were no longer
protected under the blanket 4(d) rule and did not have any de facto protections in the absence of a
species-specific 4(d) rule. Instead, these species had protective regulations only if FWS
promulgated a species-specific 4(d) rule, similar to how NMFS regulates threatened species. This
provision is not retroactive, so the blanket 4(d) rule continues to apply to species listed or

89 ESA §4(b)(3)(C)(iii), 16 U.S.C. §1533(b)(3)(C)(iii). T he Services determine what constitutes an emergency on a
case-by-case basis. For example, FWS issued an emergency rule to list the Columbia Basin distinct population segment
of the pygmy rabbit (Brachylagus idahoensis) as endangered in 2001, stating as reasons for the emergency listing that
“the immediate concerns for the Columbia Basin pygmy rabbit are associated with the population’s extremely small
size, history of fragmentation and extirpation, and the recent, dramatic decline in its distribution and abundance.” 66
Federal Register 59734, 59745, November 30, 2001.
90 ESA §4(d), 16 U.S.C. §1533(d).
91 T he blanket 4(d) protections for wildlife were implemented pursuant to FWS, 40 Federal Register 44425, September
26, 1975, as amended at FWS, 43 Federal Register, 18181, April 28, 1978; FWS, 44 Federal Register 31580, May 31,
1979; FWS, 70 Federal Register 10503, March 4, 2005. T he blanket 4(d) protections for plants were implemented
pursuant to FWS, 42 Federal Register 32380, June 24, 1977, as amended at FWS, 50 Federal Register 39691,
September 30, 1985.
92 84 Federal Register 44753.
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reclassified as threatened on or before September 26, 2019, that were not the subject of a species-
specific rule. However, FWS may supersede existing blanket 4(d) rule protections by
promulgating a species-specific 4(d) rule for a species listed before the regulation became
effective. FWS’s rationale for changing its approach is that eliminating the blanket 4(d) rule more
closely aligns FWS policy with that of NMFS and that species-specific 4(d) rules incentivize
conservation, reduce the need for permitting for certain actions, and streamline Section 7
consultation under ESA.93
FWS states that while it expects to promulgate a 4(d) rule concurrently with listing or
reclassifying a species as threatened, it did not find it necessary to require the simultaneous
promulgation of such a rule.94 Some have raised concerns about the 2019 regulations by arguing
that if 4(d) rules are not issued for threatened species in a timely manner or at al , the species
could be negatively affected. Others contend the effect of this rule change on species depends on
how often FWS issues 4(d) rules and how soon after listing these rules are issued.95 Under the
ESA, there is no timeline or deadline for issuing a 4(d) rule.
Experimental Populations
In 1982, Congress added experimental populations to the ESA to al ow the Services to release or
introduce individuals of a species listed as threatened or endangered outside of the species’
current range.96 An experimental population consists of the population introduced to an area, as
wel as any offspring arising solely from that population. As of October 2020, 147 experimental
populations had been designated and released by the Services under the ESA since 1982.
To qualify as an experimental population, a population must meet two criteria:
1. The Services must have authorized the release of the population.
2. The population must be wholly separate geographical y from other populations of
that species.97
Congress required the geographic separation so the introduced experimental population could be
distinguished from the natural population of the species and the natural population could be
protected from the introduced population.98 FWS has interpreted the requirement that the
populations be “wholly geographical y separate” to apply to populations of the species rather than
to individuals. For example, FWS used this interpretation when it authorized introducing
experimental populations of the gray wolf into Montana, Wyoming, and Idaho; this interpretation
al owed the agency to reintroduce the gray wolf into parts of these three states even as FWS

93 84 Federal Register 44754-44755.
94 84 Federal Register 44754-44755.
95 Environmental Policy Innovation Center, Guide to the Revised Endangered Species Regulations, at 2019, at
http://policyinnovation.org/wp-content/uploads/2020/01/ESA-final-rules-analysis.pdf.
96 P.L. 97-304 §6(6), 96 Stat. 1424; ESA §10(j), 16 U.S.C. §1539(j). Experimental population designations are
sometimes referred to as Section 10(j) rules.
97 Plants are eligible for reintroduction as experimental populations, but to date no plants have been designated as such.
98 “Joint Explanatory Statement of the Committee of Conference,” Conference Report on H.R. 6133, Congressional
Record, daily edition, September 17, 1982, pp. 24157 -24158.
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acknowledged that lone wolves might disperse to the area from a population in northern
Montana.99 When this rule was chal enged, a court upheld FWS’s interpretation.100
The Secretary determines whether each experimental population is essential or nonessential to the
survival of the species; this determination in turn affects the way the experimental population is
treated. An essential experimental population is one whose loss likely would result in appreciably
reducing the likelihood of the survival of the species in the wild. Al other populations are
nonessential experimental populations. As of this report’s publication, no experimental
populations have been designated as essential.
Because the ESA’s provisions apply somewhat differently to experimental populations than to
listed populations, the authority to release experimental populations gave the Services an
opportunity to release a population of a listed species with potential y fewer restrictions on
federal and private actions in the area.101 For example, regardless of whether the species is listed
as threatened or endangered, al essential experimental populations are regulated as threatened
species. As with threatened species, acts with respect to an essential experimental population are
prohibited only to the extent the Secretary orders in a species-specific 4(d) rule.102
For the purpose of requirements under Section 7 of the ESA (see “Section 7 Consultation Process
and Biological Opinions,” below), nonessential experimental populations are treated in the same
manner as candidate species, except when the experimental population occurs on lands of the
National Wildlife Refuge System or the National Park System.103 As such, federal agencies must
confer with the Secretary regarding any actions that might jeopardize the continued existence of
the species, but the Services need not engage in full Section 7 consultation or refrain from
irreversibly or irretrievably committing agency resources to the action unless the action takes
place on national wildlife refuges or in national parks. In addition, the Services cannot designate
critical habitat for nonessential experimental populations.
Critical Habitat
One of the ESA’s purposes is to conserve the “ecosystems upon which endangered species and
threatened species depend,” which includes their habitat.104 The loss or alteration of habitat is a
factor for listing species.105 The ESA directs the Services to designate critical habitat for listed
species and requires that federal agencies not destroy or adversely modify that habitat through
their actions.106

99 59 Federal Register 60253-60254; 59 Federal Register 60267-60269.
100 Wyo. Farm Bureau Fed’n v. Babbitt, 199 F.3d 1224, 1234, 1237 (10 th Cir. 2000).
101 T hough the Services had preexisting authority to release listed species prior to the inclusion of the authority related
to experimental populations, a court, reviewing the statute’s legislative history, concluded that Congress added this
section to address the Services’ frustration with political opposition to such reintroduction efforts borne from “fears
experimental populations would halt development projects.” Wyo. Farm Bureau Fed’n, 199 F.3d at 1231-32 (citing
H.R. Rep. No. 97-567, at 8 (1982)).
102 T he blanket 4(d) rule did not apply to experimental populations. See 83 Federal Register 35176.
103 ESA §10(j)(C)(i), 16 U.S.C. §1539(j)(C)(i).
104 ESA §2(c), 16 U.S.C. §1531(c).
105 D. M. Evans et al., “Species Recovery in the United States: Increasing the Effectiveness of the Endangered Species
Act,” Issues in Ecology, vol. 20 (Winter 2016). Hereinafter cited as Evans, “Species Recovery.”
106 ESA §4(a)(3)(A), 16 U.S.C. §1533(a)(3)(A) and ESA §7(a)(2), 16 U.S.C. §1536(a)(2).
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The ESA defines critical habitat to include geographic areas occupied or not occupied by the
species at the time of listing.107 Areas occupied by the species at the time of listing must have
physical and biological features that (1) are essential to the conservation of a species and (2) may
require certain management considerations or protection.108 Areas not occupied by the species at
the time of listing may be designated as critical habitat if the Secretary determines that such
additional areas are “essential for the conservation of the species.”109 Of particular relevance to
unoccupied areas, the Supreme Court concluded in Weyerhaeuser Co. v. U.S. Fish and Wildlife
Service that an area must be habitat for a species in order to be designated as critical habitat.110 In
response to the Court’s decision, the Services issued a final rule in December 2020 defining
habitat in the ESA implementing regulations.111 Furthermore, pursuant to regulations
promulgated in an August 2019 final rule, the Services may designate unoccupied areas as critical
habitat only if they determine that occupied areas alone are inadequate to conserve the species
and that the unoccupied areas contain one or more physical or biological features essential to the
species’ conservation.112 In general, critical habitat cannot include the entire geographical area
that a listed species could occupy, except in circumstances determined by the Secretary.113
The Secretary must designate critical habitat concurrently with listing a species “to the maximum
extent prudent and determinable.”114 If the species’ critical habitat is not determinable at the time
of listing, the Secretary may postpone designation for up to one year; after that year, the Secretary
must designate critical habitat to the maximum extent prudent based on the available
information.115 The Services’ regulations identify certain circumstances in which the Secretary
may determine that designating critical habitat is not “prudent,” including the following:
 The designation of critical habitat for a listed species would result in a greater
risk of the species being threatened by takings (e.g., if critical habitat is known,
then poachers would have a better idea of where the species resides).
 The present or threatened destruction or alteration of habitat is not a threat to the
species, or threats to the species stem solely from causes that cannot be addressed
through habitat management under Section 7 consultation.
 Areas within U.S. jurisdiction provide negligible conservation value for the
species because it resides primarily outside of U.S. jurisdiction.
 No areas meet the definition of critical habitat.
 The Secretary otherwise determines the designation of critical habitat would not
be prudent based on the best scientific data available.116

107 ESA §3(5), 16 U.S.C. §1532(5).
108 ESA §3(5), 16 U.S.C. §1532(5).
109 ESA §3(5), 16 U.S.C. §1532(5).
110 139 S. Ct. 361, 368 (2018).
111 FWS and NOAA, “Regulations for Listing Endangered and T hreatened Species and Designating Critical Habitat,”
85 Federal Register 81411, December 16, 2020. FWS issued a final rule in December 2020 that also responded, in part,
to the Weyerhauser opinion by clarifying the process by which FWS would exclude areas from being designated as
critical habitat. FWS, “Regulations for Designating Critical Habitat,” 85 Federal Register 82376, December 18, 2020.
112 50 C.F.R. §424.12. FWS and NOAA, “Endangered and T hreatened Wildlife and Plants; Regulations for Listing
Species and Designating Critical Habitat,” 84 Federal Register 45020, August 27, 2019.
113 ESA §3(5)(C), 16 U.S.C. §1532(5)(C).
114 ESA §4(a)(3)(A), 16 U.S.C. §1533(a)(3)(A).
115 ESA §4(b)(6)(C), 16 U.S.C. §1533(b)(6)(C).
116 50 C.F.R. §424.12.
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As of October 2020, the Services have designated critical habitat for approximately 1,000 listed
species, or roughly 60% of the 1,666 listed domestic animal and plant species.117 Critical habitat
size varies considerably by species. For example, FWS designated more than 9 mil ion acres of
critical habitat for the Indiana bat and the Mexican spotted owl, whereas FWS designated 21
acres of critical habitat for the Leon Springs pupfish.118
Designation of Critical Habitat
The Secretary designates critical habitat based on the best scientific data available after
considering potential economic, national security, and other relevant impacts that may arise from
designating areas as critical habitat.119 Unlike listing decisions where the Secretary cannot
consider economic factors, the Secretary must consider economic factors when designating
critical habitat. The Secretary may exclude any area from designation as critical habitat if the
benefits of excluding the area outweigh the benefits of designating it as critical habitat, unless the
best available scientific and commercial data indicate that failing to designate such area as critical
habitat could result in the species’ extinction.120
Revisions to Critical Habitat Regulations in 2019 Rules
In August 2019, the Services promulgated a final rule—effective September 26, 2019—addressing the designation
of critical habitat. The Services amended the list of circumstances under which the Services might find it prudent
not to designate critical habitat. The revised regulations replaced the circumstance that designating critical habitat
would not benefit the species with four other circumstances. For example, the Secretary could determine that
designating critical habitat is not prudent because no areas meet the definition of critical habitat or there are no
habitat-based threats to the species (e.g., the conservation of a species threatened solely by il egal trade may not
effectively be addressed through habitat management).
The final rule also clarified when the Secretary may designate unoccupied areas as critical habitat. Under the ESA,
unoccupied areas must be essential to the species’ conservation to be critical habitat. The final rule specified that
for unoccupied areas to be deemed essential, the Secretary must find that the species’ occupied habitat at the time
of listing is inadequate to ensure the species’ conservation. The Secretary also must determine that it is reasonably
certain the unoccupied area wil contribute to the species’ conservation and that the unoccupied area contains at
least one physical or biological feature essential to the species’ conservation, as defined in the regulation.
Source: FWS and National Oceanic and Atmospheric Association (NOAA), “Endangered and Threatened
Wildlife and Plants: Regulations for Listing Species and Designating Critical Habitat,” 84 Federal Register 45020-
45053, August 27, 2019; FWS, “Endangered and Threatened Wildlife and Plants: Regulations for Designating
Critical Habitat,” 85 Federal Register 55398-55407, September 8, 2020.
The Secretary can revise critical habitat designations independently at any time or pursuant to a
petition. For petition-initiated requests, the ESA contains timelines for addressing revisions to
critical habitat. As with petitions for listing or delisting, the Secretary, to the maximum extent
practicable, has 90 days from receiving a petition to revise critical habitat to determine whether
the petition contains sufficient scientific information to show that a revision may be warranted.

117 T he information at FWS, “ECOS – T hreatened & Endangered Species Active Critical Habitat Report ,” at
https://ecos.fws.gov/ecp/report/table/critical-habitat.html, is updated daily. For marine species, see ESA T hreatened and
Endangered Species at https://www.fisheries.noaa.gov/species-directory/threatened-endangered.
118 FWS, “ECOS – T hreatened & Endangered Species Active Critical Habitat Report ,” at https://ecos.fws.gov/ecp/
report/table/critical-habitat.html.
119 ESA §4(b)(2), 16 U.S.C. §1533(b)(2).
120 ESA §4(b)(2), 16 U.S.C. §1533(b)(2).
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The Secretary has 12 months from receiving the petition to make a final determination on how to
proceed with the requested revision and publish the finding in the Federal Register.121
The ESA exempts Department of Defense land from being designated as critical habitat in certain
situations. The National Defense Authorization Act for Fiscal Year 2004 (P.L. 108-136) amended
the ESA to specify that the Secretary shal not designate critical habitat on lands controlled by the
Department of Defense if those lands are subject to an Integrated Natural Resource Management
Plan (INRMP) under the Sikes Act (16 U.S.C. §670a).122 For the provision to apply, the Secretary
must determine the INRMP provides “a benefit” to the lands that otherwise might have been
designated as critical habitat.123 The ESA also directs the Secretary to consider national security
when designating critical habitat. According to legislative history, Congress added these
provisions in response to assertions that designating critical habitat on some military lands was
interfering with military training and readiness activities.124

121 ESA §4(b)(3)(D), 16 U.S.C. §1533(b)(3)(D).
122 ESA §4(a)(3)(B), 16 U.S.C. §1533(a)(3)(B). An Integrated Natural Resource Management Plan is a planning
document that provides Department of Defense installations guidance to implement landscape -level management
actions to conserve natural resources in collaboration with various stakeholders. T he authority for conducting these
plans is under t he Sikes Act (16 U.S.C. §670(a)-670(f)).
123 ESA §4(a)(3)(B)(1), 16 U.S.C. §1533(a)(3)(B)(1). T he military remains subject to the ESA’s other provisions,
including those on consultation and taking.
124 For example, see U.S. Congress, House Committee of the Wh ole House on the State of the Union, National Defense
Authorization Act for Fiscal Year 2003, Conference Report to Accompany H.R. 4546, 107th Cong., 2nd sess., November
12, 2002, H.Rept. 107-772 (Washington: GPO, 2002), p. H8452.
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Conservation Value of Designating Critical Habitat
There is an ongoing debate as to the conservation value of designating critical habitat under the ESA. Some
stakeholders contend that critical habitat offers little protection for a species beyond the other ESA protections
available to listed species (e.g., prohibited acts under Section 9 and the consultation requirements under Section
7). Thus, in their view, the expense of designation, which may arise from complying with consultation under ESA
Section 7 (see “Section 7 Consultation Process and Biological Opinions” in this report) and the perception of a
smal margin of additional conservation benefit make critical habitat requirements a poor use of budgetary
resources. In summary, some stakeholders view critical habitat as a regulatory burden of the ESA rather than a
conservation benefit that supplements the ESA’s prohibition on taking certain listed species.
In contrast, some observers argue that critical habitat designation provides an added conservation benefit,
particularly when it includes areas not currently occupied by the species. They assert the fol owing potential
benefits of designating critical habitat:

Designation of critical habitat may provide additional protection for listed species in the context of federal
actions. Federal agencies must consider whether their actions are likely to destroy or adversely modify
critical habitat under the Section 7 consultation provisions. If critical habitat were not designated, Section 7
consultations would be limited to whether actions jeopardize a species’ continued existence.

Designation of critical habitat requires the Secretary to consider what habitat is essential for conservation of
the species and the economic and other effects of designating critical habitat. Analyzing the economic effects
of designation might inform landowners on how to manage their lands to support the species and reduce
economic costs.

Critical habitat might inform landowners where listed species may be located, al owing landowners to avoid
taking such species and incurring the associated penalties.

Critical habitat designation might encourage landowners to modify land uses that go beyond statutory
requirements.

The process of designating critical habitat might yield scientific information about the species that benefits
habitat conservation and recovery planning and provides information for permitting incidental take.

Critical habitats may serve as connecting corridors between populations, areas for existing populations to
expand into, or areas in which new populations may be reintroduced. In addition, unoccupied habitat might
be important for species that migrate or are forced from their current habitat due to environmental changes,
such as changes to climate (e.g., increased drought) or the ecosystems in which the species resides (e.g., sea
level rise and saltwater intrusion).
Sources: R. J. Scarpel o, “Statutory Redundancy: Why Congress Should Overhaul the Endangered Species Act to
Exclude Critical Habitat Designation,” Boston Col ege Environmental Affairs Law Review, vol. 30, no. 399 (2003), pp.
399-431; A. N. Hagen and K. E. Hodges, “Resolving Critical Habitat Designation Failures: Reconciling Law, Policy,
and Biology,” Conservation Biology, March 27, 2006, pp. 356-366; K. Suckling and M. Taylor, “Critical Habitat and
Recovery: A Legal, Case Study, and Quantitative Review,” in D. D. Goble, J. M. Scott, and F. W. Davis, eds., The
Endangered Species Act at 30: Renewing the Conservation Commitment (Washington, DC: Island Press), 2005.
Recovery of Listed Species
To guide recovery efforts, the ESA requires the Secretary to develop recovery plans for the
conservation and survival of listed species, unless the Secretary finds that developing a recovery
plan would not benefit the species.125 Recovery plans aim to identify the listed species’ condition
and threats the species faces (i.e., conduct a species status assessment) and to provide a vision for
and pathway toward the species’ recovery (i.e., recovery implementation strategy). The Services’
recovery planning guidance notes that “recovery recommendations are based on resolving the
threats to the species and ensuring self-sustaining populations in the wild.”126

125 ESA §4(f), 16 U.S.C. §1533(f).
126 NMFS, Interim Endangered and Threatened Species Recovery Planning Guidance Version 1.4 , July 2018.
Hereinafter cited as NMFS, Recovery Planning Guidance.
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A 1988 ESA amendment added requirements for recovery plan contents.127 The law specified that
each plan is to include three elements, to the maximum extent practicable:
1. A description of management actions needed to accomplish a plan’s goal for the
conservation and survival of the species
2. Objective, measurable criteria that, when met, would lead to downlisting or
delisting the species
3. The estimated time and cost of carrying out measures to achieve the plan’s
goal128
Overal , the Services have stated that recovery plans are guiding documents that are not binding
on federal agencies or other entities to implement.129 The Services use a species status assessment
(SSA), often created during the listing process, to inform the species recovery plan.130 The
Services use the best available science about a species to evaluate the species’ present and
potential future threats. An SSA assesses a species’ ability to maintain self-sustaining populations
over time.131 The Services use the three principles of conservation biology to conduct this
assessment: resilience, redundancy, and representation.132 FWS explains the principles as follows:
Representation describes the ability of a species to adapt to changing environmental
conditions, which is related to distribution within the species’ ecological settings.
Resiliency describes the ability of the species to withstand stochastic disturbance events,
which is associated with population size, growth rate, and habitat quality. Redundancy
describes the ability of a species to withstand catastrophic events, which is related to the
number, distribution, and resilience of populations. Together, the 3Rs, and their core
autecological parameters of abundance, distribution and diversity, comprise the key
characteristics that contribute to a species’ ability to sustain populations in the wild over
time. When combined across populations, they measure the health of the species as a
whole.133
The ESA requires the Services to provide the public with an opportunity to review and comment
on each new or revised recovery plan before final approval. Further, FWS has stated that its
policy is to solicit scientific peer review of recovery plans from three independent reviewers.134
The Services’ guidance provides a time frame for completing recovery plans. (See Table 1.)

127 P.L. 100-478.
128 ESA §4(f)(1)(B), 16 U.S.C. §1533(f)(1)(B).
129 NOAA, Recovery of Species Under the Endangered Species Act, July 10, 2020, at https://www.fisheries.noaa.gov/
national/endangered-species-conservation/recovery-species-under-endangered-species-act#:~:text=
Are%20Recovery%20Plans%3F-
,A%20recovery%20plan%20serves%20as%20a%20road%20map%20for%20species,support%20recovery%20of%20a
%20species.
130 Most listing, reclassification, and delisting decisions are accompanied by an SSA. T he SSA ideally is created during
the initial listing stage but can be initiated at any time, according to FWS. FWS, Species Status Assessm ent
Fram ework: An Integrated Analytical Fram ework for Conservation, Version 3.4 , August 2016, at https://www.fws.gov/
endangered/improving_esa/pdf/SSA%20Framework%20v3.4-8_10_2016.pdf. Hereinafter cited as FWS, Species
Assessm ent Fram ework. NOAA conducts population viability analyses to assess the population status of the species
that it covers.
131 FWS, “ Species Status Assessment Framework: An Integrated Framework for Conservation,” August 2016, at
https://www.fws.gov/endangered/improving_esa/pdf/SSA_Fact_Sheet -August_2016.pdf.
132 FWS, Species Assessment Framework.
133 FWS, Species Assessment Framework.
134 FWS, Delisting a Species: Section 4 of the Endangered Species Act, April 2011, at https://www.fws.gov/
endangered/esa-library/pdf/delisting.pdf. Hereinafter cited as FWS, Delisting a Species. T he ESA does not require this
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Table 1. Time Frame for Recovery Plan Development for FWS and NMFS
(policy guidance; not mandated in law)
Time Frame
Action
60 days from date of listing
Recovery outline completed and submitted
90 days from date of listing
Recovery outline approved
18 months from date of listing
Draft recovery plan completed, published in the Federal
Register for public comment, and distributed for peer
review
30 months from date of listing
Final recovery plan completed and approved
Sources: NMFS, Interim Endangered and Threatened Species Recovery Planning Guidance, Version 1.4, last updated
July 2018. (FWS has adopted these guidelines.)
The Services must provide a report to Congress on the status of recovery plan development and
implementation for al listed species every two years.135 As of October 2020, there were more
than 600 draft and final recovery plans for 1,666 species listed in the United States.136 According
to one study, as of January 2018, almost one-third of species that had been listed for more than
2½ years did not have a recovery plan.137 The study states that the main reason for not completing
recovery plans is inadequate funding for recovery planning.138
Under some circumstances, the Services may decide not to prepare a recovery plan for a listed
species. For example, the Services may decide not to prepare recovery plans for species that the
Services determine wil not receive a conservation benefit from the recovery plan; that is
expected to be delisted due to extinction or an error in listing; or whose range is entirely in a
foreign country (i.e., foreign species).139
The creation and implementation of recovery plans for listed species have generated discussion
over the plans’ usefulness for identifying when a species is recovered and can be delisted.140
Although the ESA requires recovery plans to include objective and measurable criteria for
delisting to the maximum extent practicable, the act does not require the Services to base delisting
decisions on meeting those recovery plan criteria—delisting decisions are based on a status
review pursuant to the ESA definitions and factors.141 Some stakeholders suggest that recovery
plans create false expectations and inconsistencies in delisting decisions.142 In 2019, the
Department of the Interior (DOI) responded to this concern by setting an agency goal to provide
clarity as to when a listed species can be downlisted or delisted.143 To facilitate attaining this goal,

form of review.
135 ESA §4(f)(3), 16 U.S.C. §1533(f)(3). See, for example, Conservation Cong. v. Finley, 774 F.3d 611, 620 (9th Cir.
2014); Friends of Blackwater v. Salazar, 691 F.3d 428, 429 (D.C. Cir. 2012); Fund for Animals v. Rice, 85 F.3d 535,
547 (11th Cir. 1996).
136 T he information at FWS, “Environmental Conservation Online System (ECOS) – Listed Species Summary,” at
https://ecos.fws.gov/ecp/report /boxscore, is updated daily. Some recovery plans cover more than one listed species.
137 Jacob W. Malcom and Li Ya-Wei, “Missing, Delayed, and Old: T he Status of ESA Recovery Plans,” Conservation
Letters, vol. 11, no. 12601 (2018), pp. 1 -9. Hereinafter cited as Malcom and Li, “ Missing, Delayed, and Old.”
138 Malcom and Li, “Missing, Delayed, and Old.”
139 NMFS, Recovery Planning Guidance, p. 2.2.1.
140 Evans, “Species Recovery.”
141 50 C.F.R. §424.11(e). For example, see Defenders of Wildlife v. Hall, 565 F. Supp. 2 d 1160, 1170 (D. Mont. 2008).
142 50 C.F.R. §424.11(e).
143 DOI, Ensure Clear, Quantitative Criteria for Threatened and Endangered Species Recovery Plans; DOI, Agency
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DOI stated it would require 100% of FWS-promulgated recovery plans to include quantitative
criteria that specify when a species has recovered.144
Delisting, Uplisting, and Downlisting
The processes for delisting, uplisting, or downlisting a listed species are general y the same as the
processes for listing species and use the same criteria (i.e., the definitions of endangered and
threatened species and the five listing factors under Section 4).145 As with listing decisions, the
Services must make the determination to delist, uplist, or downlist a species “solely on the basis
of the best scientific and commercial data available,” without considering possible economic or
other effects.146 The Services’ regulations state they wil delist a species if they find the species is
extinct, does not meet the definition of an endangered or threatened species, or does not meet the
definition of a species (e.g., taxonomic revision).147 The Secretary may initiate delisting or
reclassifying a species independently or may act on a petition for any change in a species’ listing
status.
The ESA mandates the Secretary review the status of each listed species at least once every five
years to determine whether the species should be delisted, uplisted, or downlisted.148 For species
with recovery plans, this five-year review may include assessing whether the species has met the
plan’s recovery goals. However, the Services are not bound to delist or downlist a species that
attains its recovery goals, nor are they prevented from downlisting or delisting a species that has
not met its recovery goals.149
After a species is delisted, the ESA requires the Services, in cooperation with the states in which
the species is found, to monitor the species’ status for at least five years.150 To implement this
requirement, the Services prepare a delisting monitoring plan, which is peer reviewed and subject
to public comment.151 Monitoring al ows the Services to assess whether the species remains
recovered (i.e., not endangered or threatened) without the ESA’s protection. The ESA also
requires the Secretary to exercise emergency authority to relist a delisted species when necessary
“to prevent a significant risk to the wel being” of the species.152 As of October 2020, no species
had been relisted on an emergency basis under this authority.

Priority Goal Action Plan, 2019, at https://assets.performance.gov/APG/Interior/
FY2019_June_Interior_Ensure_Clear_Quantitative_Criteria_for_Threatened_and_Endangered_Species_Recovery_Pla
ns.pdf.
144 DOI, Ensure Clear, Quantitative Criteria for Threatened and Endangered Species Recovery Plans.
145 ESA §4(c), 16 U.S.C. §1533(c).
146 ESA §4(b)(1)(A), 16 U.S.C. §1533(b)(1)(A); 50 C.F.R. §424.11(b).
147 50 C.F.R. §424.11(e).
148 ESA §4(c), 16 U.S.C. §1533(c) and 50 C.F.R. §424.21.
149 See, for example, Friends of Blackwater v. Salazar, 691 F.3d 428, 436 (D.C. Cir. 2012).
150 ESA §4(g), 16 U.S.C. §1533(g).
151 FWS, Delisting a Species, and NOAA, Delisting Species Under the Endangered Species Act, December 27, 2019, at
https://www.fisheries.noaa.gov/national/endangered-species-conservation/delisting-species-under-endangered-species-
act.
152 ESA §4(b)(7), 16 U.S.C. §1533(b)(7).
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ESA Section 5: Land Acquisition
Section 5 of the ESA authorizes the acquisition of land to conserve (i.e., recover) endangered and
threatened species. Approximately half of the species listed under the ESA have at least 80% of
their habitat on private lands, according to FWS.153 The act directs the Secretary of the Interior
and the Secretary of Agriculture (through the National Forest System) to establish a program to
conserve fish, wildlife, and plants, including species listed under the ESA.154 The Secretaries may
use several existing authorities, listed in the act, to achieve these purposes. The ESA also
authorizes the Secretaries to acquire lands and waters through purchase, donations, or other
means. Money from the Land and Water Conservation Fund (LWCF) may be appropriated for
these acquisitions.155 The LWCF is a federal fund derived primarily from receipts from offshore
oil and gas leases; it is used for land acquisitions by the four agencies charged with managing
most federal lands, among other things.156
FWS reports expenditures for listed species annual y and includes expenditures for land
acquisition. The last annual expenditure report was published for FY2017;157 this report lists
federal agencies’ land acquisition expenditures that are “reasonably identifiable to specific
individual species.” In FY2017, federal agencies spent approximately $51.7 mil ion and states
spent approximately $5.0 mil ion to acquire land for listed species and potential y other purposes.
Three federal agencies spent the majority of funds to acquire land to conserve listed species: FWS
spent approximately $21.1 mil ion; the U.S. Department of Agriculture spent $19.9 mil ion; and
the Bureau of Reclamation spent $9.1 mil ion.158 The greatest amount of funds spent to acquire
lands for a single species in FY2017 was approximately $11.0 mil ion for the wood stork
(Mycteria americana).
ESA Section 6: Cooperation with States
Section 6 of the ESA requires the Secretary to cooperate with the states to the maximum extent
practicable in conserving federal y protected species.159 FWS and courts have recognized the
states’ “key role” in regulating wildlife and catalyzing conservation efforts by landowners and
communities on private land.160 Section 6 enables the Secretary to facilitate state conservation
programs and to direct federal funding toward such efforts.161

153 FWS, Our Endangered Species Program and How It Works with Landowners, July 2009, at https://www.fws.gov/
endangered/esa-library/pdf/landowners.pdf.
154 ESA §5(a), 16 U.S.C. §1534(a).
155 ESA §5(b), 16 U.S.C. §1534(b).
156 T he four agencies are FWS, Bureau of Land Management, and National Park Service, all in DOI, and the Forest
Service in the Department of Agriculture. For more on the fund, see CRS Report RL33531, Land and Water
Conservation Fund: Overview, Funding History, and Issues, by Carol Hardy Vincent .
157 FWS, Federal and State Threatened and Endangered Species Expenditures FY2017 , 2018, at https://www.fws.gov/
endangered/esa-library/pdf/2017-Expenditures-Report.pdf. Hereinafter cited as FWS, Federal and State Expenditures.
158 FWS, Federal and State Expenditures.
159 ESA §6(a), 16 U.S.C. §1535(a).
160 FWS, “Grants: Overview,” updated January 30, 2020, at https://www.fws.gov/endangered/grants/; Gibbs v. Babbitt,
214 F.3d 483, 499 (4th Cir. 2000).
161 ESA §6, 16 U.S.C. §1535.
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The ESA authorizes the Secretary to enter into agreements with states to assist with state
conservation efforts.162 The Secretary may enter into agreements with states, referred to as
management agreements, to administer and manage any area created to conserve listed species. In
addition, the Secretary is required to enter into a cooperative agreement with any state that
establishes and maintains an “adequate and active” state program to conserve listed species that
the Secretary determines meets certain statutory criteria.163
Management Agreements
The Secretary may enter into management agreements with states for the administration and
management of areas established for the conservation of species listed under the ESA.164
Cooperative Agreements
A cooperative agreement between the Secretary and a state facilitates the state establishing and
maintaining its own program to conserve species listed under the ESA. To initiate the process, the
state submits a plan for the program to the Secretary. To qualify for a cooperative agreement, the
state program must include the following elements:165
 The state agency that is carrying out the program (e.g., a state’s fish and wildlife
agency) has the authority to conserve resident fish and wildlife species that are
listed under the federal or state endangered species act.
 The state has established acceptable conservation programs, consistent with the
ESA, for conserving all resident listed species that the Secretary has deemed
endangered or threatened under the ESA.
 The state agency is authorized to investigate the status and requirements for
resident species’ survival.
 The state agency is authorized to establish programs to conserve resident listed
species, including through land acquisition.
 The state provides for public participation in designating resident species as
endangered or threatened.
Similar requirements apply to cooperative agreements with states that address the conservation of
plant species.166
The ESA requires states to enter into such cooperative agreements to be eligible for federal
funding. The Secretary is authorized to provide funds to any state that has entered into a
cooperative agreement to assist with implementing the state’s program to conserve species listed
under the ESA or with monitoring candidate and delisted species, including land acquisition and
planning assistance.167 The states general y must provide at least 25% of the program costs

162 ESA §6, 16 U.S.C. §1535.
163 ESA §6(c)(1), 16 U.S.C. §1535(c)(1).
164 ESA §6(b), 16 U.S.C. §1535(b).
165 ESA §6(c)(1), 16 U.S.C. §1535(c)(1). T he Secretary has 120 days to after receiving a proposed state program to
determine whether the program is in accordance with the ESA.
166 ESA §6(c)(2), 16 U.S.C. §1535(c)(2).
167 ESA §6(d), 16 U.S.C. §1535(d).
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through matching funds (i.e., the federal component cannot exceed 75% of the cost), though the
federal component may be greater for certain multistate conservation agreements.168
The 1988 ESA amendments created a fund—known as the Cooperative Endangered Species
Conservation Fund (CESCF)—to provide funding for state grants, including land acquisition and
planning assistance.169 Although the amount of money deposited into the fund is authorized
according to requirements set in statute, money from the fund can be disbursed only through
discretionary appropriations.170 Congress can appropriate funds from the CESCF to address state
programs under cooperative agreements. The ESA requires that certain mandatory funding be
deposited into the CESCF; the amounts deposited into the CESCF are equal to (1) 5% of the total
amounts deposited in the Wildlife and Sport Fish Restoration accounts each fiscal year and (2) the
amount by which the balance of fines, penalties, and forfeited property for violations of the ESA
and the Lacey Act (P.L. 100-478) exceeds $500,000.171
Outside of cooperative and management agreements, cooperation and consultation between the
federal and state governments occurs in several other instances. For example, the federal
government is required to consult with state governments before acquiring any land or water for
the conservation of listed species.172 Table 2 shows other instances of federal-state cooperation
and consultation under the ESA.
Table 2. Selected Examples of Federal-State Cooperation Under the ESA
ESA Process
Description of Federal Cooperation with States
Listing and Critical
Works with state experts to develop a scientific foundation for listing, delisting, and
Habitat
reclassifying decisions and critical habitat designations
Provides notice to state agencies of any proposed listing or critical habitat rule in
accordance with the ESA and works with states on future listing and critical habitat plans
Candidate Species
Uses states’ expertise and solicits their information to determine which species should
be included on the list of candidate species
Works with states on conservation planning to reduce threats to candidate and listed
species
Works with states to implement candidate conservation agreements with assurances to
provide nonfederal landowners incentives to conserve candidate species
Consultation
Informs state agencies of federal agency actions that are likely to adversely affect listed
species and critical habitat, and col ects information from states to help in the
consultation process required under Section 7 of the ESA
Requests updated information, including scientific and commercial data, from the state
on the species or habitat that could help in preparing a final biological opinion
Habitat
Uses the states’ expertise in al aspects of the habitat conservation planning process for
Conservation
species under states’ jurisdiction
Planning
Col aborates with states to work efficiently on permitting activities related to listed
species

168 ESA §6(d), 16 U.S.C. §1535(d)(2)(i).
169 P.L. 100-478.
170 ESA §6(i), 16 U.S.C. §1535(i).
171 Per ESA §6(i), 16 U.S.C. §1535(i), an amount equal to 5% of the funds deposited into the Federal Aid to Wildlife
Restoration Fund (the program that administers this fund is also known as Pittman -Robertson; 16 U.S.C. §§669 et seq.)
and the Federal Aid to Sport Fish Restoration Fund (the pr ogram that administers this fund is also known as Dingell-
Johnson; 16 U.S.C. §§777 et seq.) is deposited into the Cooperative Endangered Species Conservation Fund.
172 ESA §6(a), 16 U.S.C. §1535(a).
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ESA Process
Description of Federal Cooperation with States
Recovery
Uses the states’ expertise in al aspects of the recovery planning process for species
under states’ jurisdiction, including implementing recovery plans
Uses states’ expertise and authority in designing monitoring programs for species that
have been delisted
Works with states to design and encourage the use of safe harbor agreements to assist
in the recovery of listed species
(Safe harbor agreements are voluntary agreements between the Services and nonfederal
landowners that provide nonfederal landowners assurances the Services wil not impose
restrictions on their land if a landowner conducts conservation actions that benefit listed
species or species that might be listed in the future)
Source: FWS and National Oceanic and Atmospheric Association (NOAA), “Revised Interagency Cooperative
Policy Regarding the Role of State Agencies in Endangered Species Act Activities,” 81 Federal Register 8663-8665,
February 22, 2016.
To al ow for a continuing state role in endangered species conservation, the ESA’s preemption of
state law is limited. The ESA voids any state regulation that addresses the import or export of, or
interstate or foreign commerce in, listed species and either (1) permits actions the ESA prohibits
or (2) prohibits actions the ESA al ows (e.g., in an exemption or permit).173 The act otherwise
al ows states to retain and enforce laws or regulations that aim to conserve listed species. Further,
any state law or regulation that addresses taking listed species may be more restrictive than ESA
and the accompanying regulations—but not less.174
Most states have enacted laws aiming to protect endangered or threatened species.175 Forty-four
states have statutes that al ow the state government to identify species in danger of extinction and
provide some form of protection for these species.176 Of the other six states, Alabama, West
Virginia, and Wyoming do not have any statutes providing for identifying or conserving

173 ESA §6(f), 16 U.S.C. §1535(f).
174 ESA §6(f), 16 U.S.C. §1535(f).
175 State endangered species acts may include federally listed species and additional species not listed under the federal
ESA. T hree states have no provisions (Alabama, West Virginia, and Wyoming), and several states have varied
protections.
176 ALASKA STAT. §§16.20.180 – 16.20.270; ARIZ. REV. STAT. ANN. §§17-268, 17-296 – 17-298.01, 17-314; CAL. FISH
& GAME CODE §§1900 – 1913, 2050 – 2089.26; COLO. REV. STAT. §33-2-101 – 33-2-107; CONN. GEN. STAT. ANN.
§§26-303 – 26-316; DEL. CODE. ANN. tit. 7 §§601 – 605; FLA. STAT. §§379.2291, 379.411, 581.185; GA. CODE ANN.
§§27-3-130 – 27-3-133; HAW. REV. STAT. ANN. §§195d-1 – 195d-32; 520 ILL. COMP. STAT. ANN. 10/1 – 10/11; IND.
CODE ANN. §§14-22-34-1 – 14-22-34-21; IOWA CODE ANN. §§481b.1 – 481b.10; KAN. STAT. ANN. §§32-957 – 32-962;
KY. REV. STAT. ANN. §§146.601 – 619, 150.183; LA. STAT. ANN. §§56:1901 – 56:1907; ME. STAT. tit. 12 §§6971–
6978, 12801–12810; MD. CODE ANN., NAT. RES. §§10-2A-01 – 10-2A-09, 4-2A-01 – 4-2A-09; MASS. GEN. LAWS ANN.
ch. 131A §§1-7; MICH. COMP . LAWS ANN. §§324.36501 – 324.36507; MINN. STAT. §§84.0894 – 84.0895, 97A.501;
MISS. CODE ANN. §§49-5-101 – 49-5-119; MO. ANN. STAT. §252.240; MONT. CODE ANN. §§87-5-101 – 87-5-132; NEB.
REV. STAT. ANN. §§37-801 – 37-811; NEV. REV. STAT. ANN. §503.584 – 503.589; N.H. REV. STAT. ANN. §§212-A:1 –
212-A:15, 217-A:1 – 217-A:12; N.J. STAT. ANN. §§23:2A-1 – 23:2A-13, 13:1B-15.151 – 13:1B-15.158; N.M. STAT.
ANN. §§17-2-37 – 17-2-46, 75-6-1; N.Y. ENV’T CONSERV. LAW §§9-1503, 11-0535; N.C. GEN. STAT. ANN. §§106-
202.12 – 106-202.22, 113-331 – 113-350; N.D. CENT. CODE ANN. §§20.1-01-02, 20.1-02-05; OHIO REV. CODE ANN.
§§1518.01 – 1518.05, 1518.99, 1531.25 – 1531.26, 1531.99; OKLA. STAT. tit. 29 §§2-109, 2-135, 5-402, 5-412, 5-412.1,
7-502, 7-601 – 7-602; OR. REV. STAT. ANN. §§496.171 – 496.192, 498.026, 564.010 – 564.994; 30 PENN. STAT. & CONS.
STAT. ANN. §2305; 32 PENN. STAT. & CONS. STAT. ANN. §5307; 34 PENN. STAT. & CONS. STAT. ANN. §§102, 925, 2167,
2924; 20 R.I. GEN. LAWS ANN. §§20-37-1 – 20-37-5; S.C. CODE ANN. §§50-1-270, 50-15-10 – 50-15-90; S.D. CODIFIED
LAWS §§34A-8-1 34A-8-13; TENN. CODE ANN. §§70-8-101 – 70-8-112, 70-8-301 – 70-8-314; TEX. PARKS & WILD.
CODE ANN. §§68.001 – 68.021, 88.001 – 88.012; VT. STAT. ANN. tit. 10 §§4518, 5401 – 5410; VA. CODE ANN. §§3.2-
1000 – 3.2-1011, 29.1-563 – 29.1-570; WASH. REV. CODE ANN. §§77-08-010, 77-12-020, 77-15-120, 77-15-130, 77-15-
135, 77-15-420; WIS. STAT. ANN. §§29.604, 29.983, 169.01, 169.30.
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endangered or threatened species. Arkansas declares a public policy of “promot[ing] sound
management, conservation, and public awareness of Arkansas’ rich diversity of native plant and
nongame animals,” including species, subspecies, and populations that are “rare, threatened,
endangered or are of special significance to the state.”177 Idaho and Utah define endangered and
threatened species under state law as including only those species identified as such under the
federal ESA.178 Idaho does not provide any further protections for listed species beyond the
federal ESA. Utah al ows certain state entities to “make determinations concerning the
management, protection, and conservation of plant species” listed or proposed for listing under
the federal ESA on state and school or institutional trust lands.179 Utah does not provide any
additional protections for listed fish, wildlife, or plants beyond the federal ESA.
ESA Section 7: Interagency Consultation
Section 7 consultation under the ESA is the process federal agencies use to interact with the
Services to address the conservation of listed species. Under Section 7(a)(1), federal agencies are
required to use their authorities to carry out programs for the conservation of listed species under
the ESA. The Services note that this provision supports a proactive conservation planning process
by federal agencies that wil enable the agencies to plan their actions and programs to al ow for
the conservation and recovery of listed species.180
Section 7(a)(2) requires federal agencies to ensure their discretionary actions, or the actions of
nonfederal parties granted approvals, permits, or funding by federal agencies, are “not likely to
jeopardize the continued existence” of any endangered or threatened species or “adversely modify
critical habitat.”181 Federal agencies undertaking actions, whether directly or through federal
approvals, permits, or funding for nonfederal parties, must consult with FWS or NMFS, as
appropriate, if those actions might affect a listed species or designated critical habitat.182 This
process is referred to as Section 7 consultation. Federal actions mandated by statute (i.e., that are
not discretionary) do not require Section 7 consultation.
Section 7 Consultation Process and Biological Opinions
The Section 7 consultation requirements apply to federal agency actions, including actions on
federal land and actions on private land with a federal nexus. The Services’ joint regulations on
Section 7 consultations define an agency action as
All activities or programs of any kind authorized, funded, or carried out, in whole or in
part, by Federal agencies in the United States or upon the high seas. Examples include, but
are not limited to:
(a) actions intended to conserve listed species or their habitat;

177 ARK. CODE ANN. §15-45-301. T he statute establishes a Nongame Conservation Committee that may expend funds
collected from voluntary checkoff designations from state income tax refunds “for the purpose of protecting,
preserving, and restoring the nongame resources of the state.” ARK. CODE ANN. §15-45-303.
178 IDAHO CODE ANN. §36-2401; UTAH CODE ANN. §23-13-2.
179 UTAH CODE ANN. §§53C-2-202 & 65A-2-3.
180 50 C.F.R. §402.01 and 84 Federal Register 44976-45018.
181 ESA §7(a)(2), 16 U.S.C. §1536(a)(2).
182 50 C.F.R. §402.02. Action includes any activity authorized, funded, or carried out by a federal agency, including
permits and licenses.
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(b) the promulgation of regulations;
(c) the granting of licenses, contracts, leases, easements, rights-of-way, permits, or grants-
in-aid; or
(d) actions directly or indirectly causing modifications to the land, water, or air.183
Federal agencies must determine whether their proposed actions might affect listed species or
designated critical habitat (i.e., whether the listed species or critical habitat may be present in the
action area).184 If the agency determines the action is likely to affect a species or critical habitat,
then the agency must consult with the Services on the action’s effects. Consultation usual y is
initiated by the action agency but may be initiated at the request of an FWS Regional Director or
NMFS’s Assistant Administrator for Fisheries.185
The federal action agency must complete a biological assessment (BA) if listed species may be
present in the area that the action would affect.186 The BA describes the proposed action and its
likely effect on listed species. It also lists activities the agency plans to undertake to mitigate any
adverse effects of the action. The BA must be based on “the best scientific and commercial data
available.”187 Action agencies use the BA to determine whether formal consultation (i.e., a request
for consultation from the agency to the Services that culminates in a biological opinion) is
necessary.188
To determine whether formal consultation might be needed, a federal action agency can engage in
informal consultation with the Services. (See Figure 3.) Informal consultation is an umbrel a
term used to describe al of the correspondence and discussions between an agency and the
Services regarding the proposed action.189 These interactions may be used to avoid the need for
formal consultation. For example, the action agency, in coordination with any nonfederal
applicant (e.g., permit applicant), might work with the Services on the design of the proposed
action during informal consultations to eliminate the potential for adverse effect on the species or
critical habitat to avoid the need for formal consultation.190 If the federal action agency
determines during the informal consultation process that the action is not likely to adversely
affect the listed species or designated critical habitat, the agency can request a written
concurrence from the applicable Service; if the Service concurs, the consultation is finished. The
Services are required to respond to this request with either concurrence or nonconcurrence within
60 days, unless the time limit is mutual y extended for a period not exceeding 120 days from the
date of the request.191 Informal consultations under the ESA outnumber formal consultations. In a
2015 study that analyzed consultations from 2008 to 2015, 81,461 informal consultations were

183 50 C.F.R. §402.02.
184 If the agency determines its proposed action will not affect a listed species or critical habitat, then the agency is not
required to undergo consultation. T he agency could be subject to penalties for violating prohibitions under the ESA if
its determination is found to be incorrect.
185 50 C.F.R. §402.14, and see the definition of Director in §402.02.
186 ESA §7(c), 16 U.S.C. §1536(c).
187 ESA §7(a)(2), 16 U.S.C. §1536(a)(2).
188 50 C.F.R. §402.2 (definition of formal consultation); 50 C.F.R. §402.12(a).
189 FWS, “ Consultations: Frequently Asked Questions,” June 10, 2020, at https://www.fws.gov/endangered/what-we-
do/faq.html#:~:text=
Informal%20consultation%20is%20an%20optional,no%20specified%20timeframe%20for%20completion .
190 See 50 C.F.R. §402.13 for more information.
191 50 C.F.R. §402.13.
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completed, compared with 6,829 formal consultations.192 This study also reported that informal
consultations under Section 7 took an average of 13 days and formal consultations took an
average of 62 days.193
Figure 3. Informal and Formal Consultation Under the ESA

Source: Congressional Research Service.
Note: Services = U.S. Fish and Wildlife Service and National Marine Fisheries Service.
If the agency requests formal consultation, the ESA has a defined process to be completed under a
specified timeline. (See Table 3.) The agency sends the BA to the appropriate Secretary, where
the appropriate Service analyzes the assessment. If the Secretary finds the action would neither
jeopardize any listed species nor adversely modify critical habitat, the Secretary issues a
biological opinion (BiOp) to that effect. The BiOp includes a written incidental take statement
(ITS).194 Incidental take is the take of a listed species as a result of an otherwise lawful action. An
ITS states the amount of take of a listed species that is anticipated from the proposed action and
provides the agency with an exemption from the prohibitions on take under Section 9 of the ESA

192 J. W. Malcom and Ya-Wei Li, “Data Contradict Common Perceptions About a Controversial Provision of the U.S.
Endangered Species Act,” Proceedings of the National Academy of Sciences, vol. 112, no. 52 (December 29, 2015).
Hereinafter cited as Malcom and Li, “Data Contradict Common Perceptions.”
193 Malcom and Li, “Data Contradict Common Perceptions.”
194 ESA §7(b)(4), 16 U.S.C. §1536(b)(4).
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for the expected level of take. This exemption is contingent on the agency complying with any
reasonable and prudent measures and the terms and conditions included in the ITS.195
Alternatively, if the proposed action is judged to jeopardize listed species or adversely modify
critical habitat, the Secretary must suggest any reasonable and prudent alternatives (RPAs) in the
issued BiOp that minimize harm to the species. A BiOp with RPAs also contains an ITS that sets
limits on take for listed species. If no RPAs are feasible, then the agency proposing the action
must (1) forgo the action, (2) modify the action and reinitiate consultation for the revised action,
(3) risk violating the ESA, or (4) obtain a formal exemption from an Endangered Species
Committee (ESC).196 The great majority of Section 7 consultations result in no jeopardy opinions,
and nearly al of the rest identify RPAs that permit the action agencies to go forward with the
proposed projects.197
The Secretary general y must conclude consultation and issue a BiOp within 90 days of receiving
an action agency’s BA for a wholly federal action, unless the Secretary and the federal agency
mutual y agree to a longer period.198 For consultations involving a nonfederal party (e.g., permit
applicant), the 90-day period may be extended up to an additional 60 days without the nonfederal
party’s permission; the Services and action agency need only provide the nonfederal party with an
explanation for the delay and the estimated time frame for completion.199 The Services and action
agency must obtain the nonfederal party’s permission to extend the consultation beyond 150 days
from its initiation.200 Pursuant to federal regulations, the action agency and the Services may enter
into an agreement to conduct an expedited consultation under Section 7 with an alternative
accelerated timeline established by the action agency and the Services.201 In general, the Services
complete formal consultations pursuant to the given timelines; however, some consultations may
take a year or more.202
BiOps may be revised through a reinitiation of formal consultation. After a consultation is
complete, federal agencies may be required to reinitiate consultation with the Services when
certain circumstances arise. Specifical y, reinitiation of consultation is required when

195 16 U.S.C. §1536(b)(4). Reasonable and prudent measures are distinct from reasonable and prudent alternatives that
may be provided by the Secretary if the action is likely to jeopardize listed species or adversely modify critical habitat.
Reasonable and prudent m easures “ refer to those actions the Director believes necessary or appropriate to minimize the
impacts, i.e., amount or extent, of incidental take.” “ Reasonable and prudent alternatives refer to alternative actions
identified during formal consultation that can be implemented in a manner consistent with the intended purpose of the
action, that can be implemented consistent with the scope of th e Federal agency’s legal authority and jurisdiction, that
is economically and technologically feasible, and that the Director believes would avoid the likelihood of jeopardizing
the continued existence of listed species or resulting in the destruction or adverse modification of critical habitat.” 50
C.F.R. §402.02.
196 16 U.S.C. §1536(g); 50 C.F.R. §402.15; 50 C.F.R. Subchapter C; FWS and NMFS, Endangered Species
Conservation Handbook: Procedures for Conducting Consultation and Conference Activities Under Sec tion 7 of the
Endangered Species Act, March 1998, at https://www.fws.gov/endangered/esa-library/pdf/esa_section7_handbook.pdf,
p. 2-11. For more information, see CRS Report R40787, Endangered Species Act (ESA): The Exem ption Process, by
Pervaze A. Sheikh. See section on Exemptions for Section 7 Consultation in this report for more information.
197 Malcom and Li, “Dat a Contradict Common Perceptions,” pp. 15844-15849.
198 ESA §7(b)(1), 16 U.S.C. §1536(b)(1); 50 C.F.R. §402.14(e). FWS and NMFS begin the 90-day clock when they
receive a complete biological assessment (BA) with all the information needed for consultation; action agencies are
often asked for more information than the data submitted in the original BA. Action agencies often object to the delays;
the Services respond that consultation requires adequate data about the project.
199 ESA §7(b)(2), 16 U.S.C. §1536(b)(2).
200 ESA §7(b)(2), 16 U.S.C. §1536(b)(2).
201 50 C.F.R. §402.14(l).
202 Malcom and Li, “Data Contradict Common Perceptions.”
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“discretionary Federal involvement or control over the action has been retained or is authorized
by law” and one or more of the following triggering events occurs:
 The amount or extent of taking specified in an incidental take statement is
exceeded.
 New information on the species or action reveals there is an effect on the species
or critical habitat that was not considered in the BiOp.
 The action is sufficiently modified so there is an effect on species and critical
habitat that was not considered in the BiOp.
 A new species is listed or critical habitat is designated that may be affected by the
action.203
Reinitiated consultation follows the same procedures and timelines as formal consultation.
Section 7 consultation also can be conducted at the programmatic level, often referred to as a
programmatic consultation. Programmatic consultations al ow federal agencies to consult with
the Services on multiple, frequently occurring, or routine actions in a particular geographic area
or on proposed programs, policies, or regulations that would provide a framework for future
actions.204 Individual projects conducted under a program covered by a programmatic BiOp
general y stil require a separate consultation under Section 7; however, with a programmatic
BiOp in place, this process may be streamlined.
One study found that between 2000 and 2017, the species that were most frequently the subject of
Section 7 consultations included Chinook salmon (Oncorhynchus tshawytscha); steelhead trout
(Oncorhynchus mykiss); Coho salmon (Oncorhynchus kisutch); and several species of sea turtles,
such as the green sea turtle (Chelonia mydas) and the loggerhead sea turtle (Caretta caretta).205
The study also determined that the U.S. Army Corps of Engineers conducted more Section 7
consultations than any other federal agency, more than triple the number completed by the U.S.
Forest Service, which had the second-most consultations. The three project types associated with
the most Section 7 consultations during the study period were waterways, transportation, and
restoration.206
Section 7 Consultation and Proposed Species
Section 7 requires federal agencies to confer with the appropriate Secretary on any federal agency action that is
likely to jeopardize the continued existence of any species proposed to be listed or to destroy or adversely modify
critical habitat proposed to be designated for such species (ESA §7(a)(4), 16 U.S.C. §1536(a)(4)). Proposed species
are “any species of fish, wildlife or plant that is proposed in the Federal Register to be listed under section 4 of the
[Endangered Species] Act.” However, agencies need not limit commitments of resources for the agency action. As
a result of the rulemaking process and limited agency resources, a species may be proposed for listing for months
or years before the species is listed or determined to no longer warrant listing. During that time, federal agencies
and private parties may undertake actions that affect the proposed species. The ESA does not extend any of the
prohibited acts for endangered species to proposed species, so nonfederal parties (e.g., private landowners, state
governments, or nonprofits) general y may engage in any activities or projects that have no federal nexus.
Implementing regulations under 50 C.F.R. §402.10 state that an action agency may hold a conference with the
Services on any action that is likely to jeopardize a proposed species or to destroy or modify its proposed critical

203 50 C.F.R. §402.16.
204 50 C.F.R. §402.13(l).
205 M. J. Evans, J. W. Malcom, and Y. W. Li, “Novel Data Show Expert Wildlife Agencies Are Important to
Endangered Species Recovery,” Nature Communications, vol. 10 (August 1, 2019). Hereinafter cited as Evans,
Malcom, and Li, “Novel Data.”
206 Evans, Malcom, and Li, “Novel Data.”
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habitat. The conference is designed to assist the federal agency and the applicant (if any) in identifying and
resolving potential conflicts at an early stage in the planning process. The conference process that applies to
species proposed for listing is distinct from the consultation process that applies to listed species. The conference
is intended to be less formal and to permit the Services to advise a federal agency on ways to minimize or avoid
adverse effects on a proposed species. A federal agency may, however, choose to undertake the more extensive
and formal consultation process even at the proposed listing stage to avoid duplication of effort later.
For more information on conference requirements for proposed species, see FWS and NMFS, Consultation
Handbook: Procedures for Conducting Consultation and Conference Activities Under Section 7 of the Endangered Species
Act, March 1998.
Exemptions for Section 7 Consultation
If the Services cannot identify any RPAs for a project to avoid jeopardizing listed species or
adversely modifying designated critical habitat and if other required conditions are met, an action
may be eligible to receive a formal exemption from the requirement that the action not jeopardize
listed species or adversely modify critical habitat.207 In addition, any action covered by a formal
exemption is deemed to not result in take of a listed species.208 If an agency wants to obtain a
formal exemption, the agency (or the affected governor[s] or license applicant[s]) may apply to
the Secretary, who passes on the application to an ESC for an exemption.209 Exemptions are
available for specific actions (e.g., water withdrawals) rather than for al actions related to a
particular species (e.g., Delta smelt). An ESC, which decides whether to provide an exemption for
the action, is composed of six specified federal officials and one individual from each affected
state.210 Five members or their representatives need to be present for a quorum; only members—
not their representatives—count toward a quorum if the committee is voting, because only
members can vote. At least five votes are required to al ow an exemption.211
Under Section 7(g), to be eligible for consideration of an exemption, the Secretary must
determine within 20 days, or a time period otherwise agreeable to the Secretary and the applicant,
that the applicant
 completed consultation requirements “in good faith and made a reasonable and
responsible effort to develop and fairly consider modifications or reasonable and
prudent alternatives”;
 conducted any required BAs; and
 “to the extent determinable ... refrained from making any irreversible or
irretrievable commitment of resources.”212

207 ESA §7(h), 16 U.S.C. §1536(h).
208 ESA §7(o)(1), 16 U.S.C. §1536(o)(1).
209 ESA §7(g), 16 U.S.C. §1536(g).
210 T he six federal officials are the Secretaries of the Interior (chair), Agriculture, and the Army; the Chair of the
Council of Economic Advisors; and the Administrators of NOAA and the Environmental Protection Agency. 16 U.S.C.
§1536(e)(3).
211 In the event that more than one state is affected by the action, the regulations provide that the states collectively cast
one vote. 50 C.F.R. §453.05.
212 ESA §7(g)(3), 16 U.S.C. §1536(g)(3). Such “irreversible or irretrievable commitment[s] of resources” are those that
would foreclose the formulation or implementation of RPAs that would avoid jeopardizing the species and/or adversely
modifying critical habitat. ESA §7(d), 16 U.S.C. §1536(d).
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These qualifying requirements ensure the exemption process is meaningful and consideration of
the issues wil not be preempted by actions already taken. Additional requirements for an
application are contained in the relevant regulations.213
The ESC shal grant an exemption for the project or activity if, based on the evidence, the ESC
determines that
(i) there are no reasonable and prudent alternatives to the agency action;
(ii) the benefits of such action clearly outweigh the benefits of alternative courses of action
consistent with conserving the species or critical habitat, and such action is in the public
interest;
(iii) the action is of regional or national significance; and
(iv) neither the federal agency concerned nor the exemption applicant made any
irreversible or irretrievable commitment of resources prohibited by subsection (d) of this
section.214
There have been three completed applications for an exemption under this process (two granted)
and three other instances in which applications were filed but the applications were withdrawn or
abandoned.215
The ESA also provides alternative avenues for granting exemptions under certain circumstances.
Specifical y, exemptions may be approved under alternative procedures when the action concerns
international treaty obligations,216 national security,217 and presidential y declared disasters.218 The
ESA does not have a general provision that al ows exemptions in other emergency conditions.
ESA Section 9: Prohibitions
Section 9 of the ESA enumerates various acts that are prohibited with respect to endangered
species. For threatened species not covered by FWS’s blanket 4(d) rule, the Services may apply
Section 9 prohibitions to such threatened species through a species-specific 4(d) rule. Absent a
species-specific 4(d) rule, the Section 9 prohibited acts do not extend to threatened species.219
The Section 9 prohibitions include the following:
 Importing or exporting endangered species into or out of the United States
 Taking endangered species within the United States or U.S. territorial seas and
taking such species on the high seas

213 50 C.F.R. parts 450-453.
214 ESA §7(h)(1)(A), 16 U.S.C. §1536(h)(1)(A).
215 For more information, see CRS Report R40787, Endangered Species Act (ESA): The Exemption Process, by
Pervaze A. Sheikh.
216 ESA §7(i), 16 U.S.C. §1536(i).
217 ESA §7(j), 16 U.S.C. §1536(j).
218 ESA §7(p), 16 U.S.C. §1536(p). However, 50 C.F.R. §13.4 states that in emergency conditions, the FWS Director
“may approve variations from the requirements of this part [the general permit procedures] when he finds that any
emergency exists and that the proposed variations will not hinder effective administration of [the subchapter on
permits], and will not be unlawful.”
219 In the absence of a species-specific 4(d) rule for threatened species listed by FWS before September 26, 2019, the
blanket 4(d) rule extended essentially the same protections and prohibitions to those species as apply to endangered
species.
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 Possessing, sel ing, or transporting any unlawfully taken endangered species
 Delivering, receiving, transporting, or sel ing in interstate or foreign commerce
any endangered species
 Violating any regulation promulgated by FWS or NMFS pertaining to any
endangered or threatened species220
Similar prohibitions apply to endangered plants, except the prohibitions most similar to the take
prohibitions general y apply only to endangered plant species located in areas under federal
jurisdiction.221
The ESA also prohibits attempting to commit, soliciting another to commit, or causing to be
committed any prohibited act.222 The ESA’s prohibitions apply broadly to any person (as defined
by the act) subject to the jurisdiction of the United States.223 Sections 9 and 10 of the ESA al ow
for certain exceptions from the prohibitions.224
Import and Export Provisions Under Section 9 of the ESA
The ESA general y requires any person who engages in the business of importing or exporting fish, wildlife, or
plants to obtain permission from the appropriate Secretary. The ESA does not specify that the species must be
listed, thus making the law broadly applicable to al species, with some exceptions. Those persons who are
required to receive permission must keep records on their imports and exports; provide access to their place of
business for inspections; file required reports with the Secretary; and use certain ports designated by the
Secretary, unless the Secretary deems it appropriate and consistent with the ESA to permit importation or
exportation elsewhere.
Source: ESA §9(d)-(f), 16 U.S.C. §1538(d)-(f).
ESA Section 10: Exceptions
Section 10 of the ESA authorizes the Secretary to issue a permit to exempt certain actions from
ESA prohibitions. Eligible actions include taking species for scientific purposes, enhancing the
survival of listed species, and incidental taking of listed species during otherwise lawful
actions.225 The following sections discuss these exemptions.
Permits for Scientific Purposes and Enhancing the Survival of
Species
Section 10(a)(1)(A) authorizes the Secretary to issue permits to carry out acts otherwise
prohibited by Section 9 of the ESA for scientific purposes and to “enhance the propagation and
survival” of listed species; these permits may be used to establish experimental populations.226
Scientific permits issued by the Services may authorize take of listed species to study the biology
and long-term survival needs of a listed species, among other things. The Services also issue

220 ESA §9(a), 16 U.S.C. §1538(a).
221 ESA §9(a)(2), 16 U.S.C. §1538(a)(2).
222 ESA §9(g), 16 U.S.C. §1538(g).
223 ESA §9(a), 16 U.S.C. §1538(a).
224 ESA §§9(b) and 10, 16 U.S.C. §§1538(b) and 1539.
225 ESA §10, 16 U.S.C. §1539(a).
226 ESA §10(a)(1), 16 U.S.C. §1539(a)(1).
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recovery permits under this same authority. Recovery permits are issued to assist in the recovery
of listed species and may include exemptions from prohibitions of take.227 Some activities that
might be authorized under a recovery permit include genetic studies, abundance surveys, and
telemetric monitoring (i.e., tracking species using sensors) of listed species.
The Services issue enhancement of survival permits (enhancement permits) for activities that
provide a conservation benefit for listed species or unlisted species in the event they become
listed in the future. For example, enhancement permits are used to approve activities in
conjunction with a candidate conservation agreement or a safe harbor agreement (see textbox
below).
Safe Harbor Agreements
Because many listed species inhabit private lands, the Services created policies that encourage private landowners’
involvement in the conservation of these species. To incentivize landowners to aid in species conservation, the
Services may use safe harbor agreements (SHAs). SHAs are voluntary agreements between the Services and
nonfederal landowners that provide nonfederal landowners assurances that the Services wil not require changes
in management activities on their land if additional listed species enter into their property or if the distribution of
listed species increases on their property if a landowner conducts conservation actions that benefit listed species
or species that might be listed in the future. The assurance is provided by an Enhancement of Survival Permit
issued to the property owner. The permit authorizes incidental take of listed species from actions taken by the
landowner in the SHA.
Some conservation activities that might be covered under SHAs include restoring habitat for species; reducing
habitat fragmentation; and creating buffers for habitat, such as vegetative buffers for streams, among others. An
SHA benefits landowners by ensuring potential restrictions on land use or activities wil not be applied if newly
listed species inhabit their lands or if existing listed species move onto their land. This assurance is provided by an
enhancement permit issued to the landowner. The permit can authorize incidental take of species that may result
from conservation activities included in the SHA.
Source: FWS, “Safe Harbor Agreements: Frequently Asked Questions,” January 2020, at https://www.fws.gov/
endangered/landowners/landowners-faq.html.
Enhancement permits can be issued for several other activities, including captive breeding
programs that aim to improve the survivorship, reproduction, genetic vitality, and management of
populations. Enhancement permits also can be used to exhibit living listed species to educate the
public on the species’ conservation needs and ecological roles.228 Zoos, for example, may obtain
such permits to conserve listed species.229
Enhancement permits sometimes are issued to import and export listed species. An enhancement
permit may be used to import sport-hunted trophies of foreign species listed under the ESA into
the United States. These enhancement permits may be justified based on the incentives al owing
such imports to provide for increasing the survival of the species in its native habitat. For
example, if trophy hunters are al owed to harvest a limited number of animals, and if funds
generated by the hunters’ activities (e.g., through permits or taxes) are transferred to a
conservation program that supports a population of the same species, then the limited take of
individuals through hunting could enhance the species’ survival by providing an incentive for
conservation.

227 FWS, Recovery 10(a)(A)(1) Permits Program, April 23, 2020.
228 A. Haas, “Interpreting ‘Enhancement of Survival’ in Granting Section 10 Endangered Species Act Exemptions to
Animal Exhibitors,” Pace Environmental Law Review, July 2015, pp. 956-982. Hereinafter cited as A. Haas,
“Enhancement of Survival.”
229 A. Haas, “Enhancement of Survival.”
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The ESA states that the Secretary may grant permits under Section 10(a)(1)(A) if the Secretary
finds that permits were applied for in good faith, wil not disadvantage endangered species, and
wil be consistent with the purposes and policy of the ESA.230
Permits for Incidental Taking of Species and Habitat Conservation
Plans
For actions by nonfederal parties that might result in take of a listed species but have no federal
nexus (e.g., a loan or permit), the Secretary may issue permits to al ow incidental take of listed
species for otherwise lawful actions.231 To obtain an incidental take permit (ITP), a nonfederal
entity must submit a permit application and a habitat conservation plan (HCP), under Section
10(a)(1)(B) of the ESA.232 The HCP describes the anticipated effects of the nonfederal applicant’s
action on listed species,233 as wel as the steps to be taken to minimize and mitigate that impact,
funding for the mitigation, alternatives that were considered and rejected, and any other measures
the Secretary may require. HCPs also must comply with other policies by including biological
goals and outcomes for the species covered by the HCP, adaptive management provisions,234
monitoring protocols, permit duration, and public participation in the process. The permit
applicant must use the best available science when creating HCPs and ITPs, and in some cases
HCPs are reviewed by independent scientists.235
Once the permit application and draft HCP are completed, they general y are submitted to the
Services along with an implementation agreement. The Secretary evaluates the permit application
(including the HCP) and determines if it meets and abides by the following criteria specified
under the ESA:
 The taking of species wil be incidental.
 The applicant wil minimize and mitigate the action’s effects on species to the
maximum extent practicable.
 The applicant wil ensure that adequate funding of the mitigation measures is
required.
 The taking of the species wil not appreciably reduce the survival and recovery of
the species in the wild.
 Any other measures prescribed by the Secretary.236

230 ESA §10(d), 16 U.S.C. §1539(d).
231 ESA §10(a), 16 U.S.C. §1539(a).
232 ESA §10(a)(2)(A), 16 U.S.C. §1539(a)(2)(A). Also, see 50 C.F.R. §17.3, which defined conservation plan as “the
plan required by section 10(a)(2)(A) of the ESA that an applicant must submit when applying for an incidental take
permit. Conservation plans also are known as ‘habitat conservation plans’ or ‘HCPs.’”
233 ESA §10(a)(2)(A), 16 U.S.C. §1539(a)(2)(A).
234 Adaptive management is the process of incorporating new scientific and programmatic information into the
implementation of a project or plan to ensure the activity’s goals are being reached efficiently. It promotes flexible
decision-making to modify existing activities or create new activities if new circumstances arise (e.g., new scientific
information) or if projects are not meeting their goals.
235 FWS, Habitat Conservation Plans Under the Endangered Species Act, April 2011, at https://www.fws.gov/
endangered/esa-library/pdf/hcp.pdf.
236 ESA §10(a)(2)(B), 16 U.S.C. §1539(a)(2)(B).
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Because the issuance of an ITP is considered a federal action by the Services, FWS or NMFS
must complete an intra-Service consultation subject to Section 7 and issue a BiOp assessing the
effects of the ITP on the listed species and critical habitat. 237 Upon completion of the Section 7
consultation, an ITP al ows nonfederal entities or persons to legal y proceed with a project that
incidental y takes listed species as specified under the ITP. The permit holder also benefits from
the No Surprises regulation;238 under this regulation, private landowners are assured that if
unforeseen circumstances arise, FWS wil not require an additional commitment of resources to
address species in an HCP without the landowner’s consent.239 This policy was created to
incentivize private landowners to conserve species and their habitat using Section 10 permits. The
actions agreed to in an HCP are made binding through the ITP. Typical y, ITPs have an expiration
date; however, mitigation under the HCP can be in perpetuity. If the terms of the ITP are violated,
the action could result in il egal take under Section 9 of the ESA.
Al applications for exceptions or permits under Section 10 must be published in the Federal
Register and open for comments for 30 days (this period may be waived if the listed species is
threatened and no alternatives are available to the applicant). In addition, any information
received as part of the application must be made public.240
Comparison of Section 10 and Section 7 Consultation
Permitting under Section 10 and consulting under Section 7 lead to an ITP and an ITS,
respectively, which al ow applicants to proceed with projects or actions that affect listed species
without violating the take prohibitions. Table 3 summarizes some similarities and several
differences between the processes under Section 10 and Section 7. The comparison below is not
comprehensive but focuses on key aspects of the two processes under the ESA.
Table 3. Comparison of Section 7 Consultation and Section 10 Permitting
Under the ESA
Characteristic
Section 7 Consultation
Section 10 Permitting
Applicants
Federal agencies or in some cases
Nonfederal entities that are proposing actions
nonfederal agencies that have been assigned
with no federal nexus.
as an applicant under various authorities.
Applicable
Federal actions or nonfederal actions that
Nonfederal entities that believe their
Actions
have a federal nexus.
otherwise lawful activities wil result in the
incidental take of a listed species under the
ESA.
Applicable
Section 7 consultation is initiated when a
Section 10 permit is sought when actions are
Biological
federal agency determines a project or
likely to result in take of a listed species and any
Conditions
action might jeopardize species listed under
taking is incidental to carrying out the
the ESA or adversely modify designated
otherwise lawful activity. This applies only to
critical habitat. Consultation applies to
wildlife, since there is no prohibition on take
plants, fish, and wildlife.
for plants.

237 FWS and NOAA, Habitat Conservation Planning and Incidental Take Permit Processing, FWS and NOAA
Handbook, December 21, 2016, p. 3-27, at https://www.fws.gov/endangered/esa-library/pdf/HCP_Handbook.pdf.
238 50 C.F.R. §17.3, §17.22(b)(5) and §17.32(b)(5).
239 50 C.F.R. §17.3, §17.22(b)(5) and §17.32(b)(5).
240 ESA §10(d), 16 U.S.C. §1539(d).
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Characteristic
Section 7 Consultation
Section 10 Permitting
Scope
Section 7 covers a proposed project or
Section 10 permit covers a species or multiple
action and considers the effect on one or
species and the effects of actions on those
more species.
species.
Application
Agencies may consult informal y with the
The nonfederal entity applies for an incidental
Process
U.S. Fish and Wildlife Service and the
take permit (ITP) to lawful y carry out its
National Marine Fisheries Service (the
action with take of listed species.
Services) before requesting a formal
The applicant for an ITP must submit a habitat
consultation. Informal consultations entail
conservation plan (HCP) that shows the
communication with the Services about
action’s likely impact, steps to minimize and
whether formal consultation is required and
mitigate that impact, funding sources for the
whether the action may be modified to
mitigation, alternatives that were considered
avoid the need for formal consultation. A
and rejected, and any other measures the
federal agency may prepare a biological
Secretary may require.
assessment (BA) before informal
consultation and for formal consultation.

Formal consultation occurs when the action
may affect a listed species. The Services
review the BA and issue a biological opinion
(BiOp).
Time Limits
The appropriate Secretary is to complete
There are no time limits in the ESA for
consultation within 90 days, unless the
completing an HCP and issuing an ITP.
Secretary and the applying federal agency
agree to extend the time period—with
notice to or permission of any nonfederal
applicant, depending how long the extension
is.
The Secretary has 45 days after a formal
consultation to issue a BiOp.
Public Review
There is no requirement that the Services
The ESA requires a 30-day comment period on
publish a draft BiOp for public review. Draft
ITPs; however, if National Environmental
BiOps can be provided to the federal agency
Policy Act requirements are concurrently
or applicant for review.
being met, the comment period could be
longer.
Critical Habitat
The adverse modification of critical habitat
Critical habitat does not directly relate to
by an action could trigger a Section 7
Section 10 permits; however, if the ITP issued
consultation. (16 U.S.C. §1536(a)(2).)
is likely to result in the destruction or adverse

modification of critical habitat, then the
Services may require a Section 7 consultation
to issue the Section 10 permit.
Final Plan or
A BiOp is issued through formal
An HCP, submitted by the nonfederal
Opinion
consultation. (16 U.S.C. §1536(b).) A BiOp is
applicant, describes the anticipated effects of
Describing
the Secretary’s opinion on how the action
the action on species and how the effects can
Efforts or
wil affect listed species and critical habitat.
be minimized and mitigated. (16 U.S.C.
Changes to
A BiOp could find that an action would
§1539(a)(1)(A).)
Address the
neither jeopardize a species nor adversely

Species
modify critical habitat. Alternatively, if the
proposed action is judged likely to
jeopardize listed species or adversely modify
critical habitat, the Secretary must suggest
any reasonable and prudent alternatives in
the BiOp that would avoid harm to the
species.
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Characteristic
Section 7 Consultation
Section 10 Permitting
Incidental Take
An incidental take statement (ITS) is issued
An ITP is required when otherwise lawful
with a BiOp if the project or activity is
nonfederal activities result in the take of
expected to take listed species. The ITS
species. (16 U.S.C. §1539(a)(1)(B).) An HCP
specifies the terms and conditions under
must accompany an ITP.
which the federal action must proceed in
The ITP authorizes the take of the listed
order to minimize take of the listed species.
species and not the action that is being
(16 U.S.C. §1536(b)(4).)
proposed. This permit al ows the applicant to
legal y proceed with their proposed activity
with respect to the ESA.
Duration
The BiOp and the ITS can be indefinite or
Permit time is set at the time of issuance.
have a predetermined lifetime.
Permits can have long time spans, some as long
as 100 years.
Conditions for
ESA regulations require reinitiation of
Changes in the implementation of an HCP
Changes to
consultation if certain conditions arise,
might require amendments to HCPs and the
Permissible
including changes to the project or actions
ITP, among other things. ITPs also may be
Activities
associated with the project that affect listed
renewed.
species or critical habitat in ways not
anticipated in the BiOp.
No Surprises
Not applicable.
No Surprises assurances are provided to
Policy
nonfederal landowners whose land is included
in an HCP. Private landowners are assured
that if unforeseen circumstances arise, FWS
wil not require an additional commitment of
resources to address species in an HCP
without the landowner’s consent.
Decision Not to If no reasonable and prudent alternatives are
If jeopardy to a species is anticipated due to
Issue an
feasible, then the agency proposing the
the action’s effect on a species, an ITP may not
Incidental Take
action must (1) forgo the action, (2) risk
be awarded. Further, an ITP may be revoked if
Statement or
incurring penalties under the ESA, or (3)
jeopardy to a species cannot be avoided.
Permit for an
obtain a formal exemption from the
Action
penalties of the ESA.
Frequency of
Thousands of Section 7 informal and formal
As of October 2020, approximately 700 HCPs
Use
consultations have been performed.
and 865 ITPs had been approved.
Sources: CRS, with information from the ESA (P.L. 93-205, 87 Stat. 884, 16 U.S.C. §§1531-1544); FWS, Habitat
Conservation Plans Under the Endangered Species Act, April 2011, at https://www.fws.gov/endangered/esa-library/
pdf/hcp.pdf.; FWS and NOAA, Habitat Conservation Planning and Incidental Take Permit Processing, FWS and NOAA
Handbook, December 21, 2016, at https://www.fws.gov/endangered/esa-library/pdf/HCP_Handbook.pdf.; FWS
and NMFS, Consultation Handbook: Procedures for Conducting Consultation and Conference Activities Under Section 7 of
the Endangered Species Act, March 1998; FWS, “Consultation: Frequently Asked Questions,” at
https://www.fws.gov/endangered/what-we-do/faq.html.
Notes: This table is not comprehensive and represents only key comparisons between the Section 7 consulting
and Section 10 permitting processes.
ESA Section 11: Penalties and Enforcement
Section 11 of the ESA imposes civil and criminal penalties for violating the ESA or ESA permits,
certificates, or regulations.241 Any person who violates any ESA provision or any regulation,
permit, or certificate issued pursuant to the ESA may be subject to civil penalties for each
violation. Knowing violators and persons engaged in business as importers or exporters of fish,

241 ESA §11, 16 U.S.C. §1540.
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wildlife, or plants may be subject to higher civil penalties. Any person who knowingly violates
ESA statutory provisions, permits, certificates, or regulations also may be subject to criminal
fines or imprisonment upon conviction.242 Fish, wildlife, and plants connected with any such
violations and any items used to facilitate the violation (e.g., guns, traps, vehicles, or aircraft) are
subject to forfeiture.243 Violators can defend themselves against both civil al egations and
criminal charges if they can demonstrate that they violated the act believing, in good faith, that
they were protecting themselves or another person from bodily harm from any listed species.244
The ESA is enforced by the Secretary of the Interior, Commerce, Treasury, or department within
which the Coast Guard is operating. The act also contains a number of specific enforcement
authorities, such as inspection, arrest without warrant in certain instances, search, and seizure.245
The ESA provides for a reward fund that is funded by penalties, fines, or forfeited property
collected from violators.246 The ESA directs the Secretary of the Interior, Commerce, or the
Treasury, as appropriate, to pay a reward to any person who provides information that leads to an
arrest, criminal conviction, civil penalty assessment, or forfeiture of property for ESA violations.
The appropriate Secretary is to designate the amount of the award. The Secretary also may use the
reward fund to pay for temporary care of species while associated civil or criminal proceedings
are pending.
Citizen Suits
Any person may bring a lawsuit in federal district court (1) to enjoin anyone, including
governmental entities, who the person al eges to be violating any provision of the ESA or its
regulations; (2) to compel the Secretary to enforce prohibitions on taking listed species; or (3) to
compel the Secretary to perform a nondiscretionary duty under the ESA’s listing-related
provisions in Section 4.247 The person general y must provide written notice of intent to sue at
least 60 days prior to bringing the action.248 The person cannot file a suit to enjoin violations or
compel the Secretary to enforce take prohibitions if the Secretary is “diligently” pursuing an
enforcement action for those violations.249 The ESA expressly al ows the court to award litigation
costs and attorneys’ fees to any party for whom the court determines such an award is
appropriate.250
Citizen suits frequently have been used to compel agency action and direct agency resources
under the ESA. ESA citizen suits have been used to compel the Services to list, reclassify, or
delist species; chal enge delays in listing decisions; oppose listing, reclassification, or delisting
rules; address critical habitat designations and revisions; and chal enge BiOps and use of the
Section 7 consultation process.251 A subset of citizen suits has addressed deadlines under the ESA

242 ESA §11(b), 16 U.S.C. §1540(b).
243 ESA §11(e)(4), 16 U.S.C. §1540(e)(4).
244 ESA §11(a)(3), 16 U.S.C. §1540(a)(3).
245 ESA §11(d)-(f), 16 U.S.C. §1540(d)-(f).
246 ESA §11(d), 16 U.S.C. §1540(d).
247 ESA §11(g), 16 U.S.C. §1540(g).
248 ESA §11(g)(2), 16 U.S.C. §1540(g)(2).
249 ESA §11(g)(2), 16 U.S.C. §1540(g)(2).
250 ESA §11(g)(4), 16 U.S.C. §1540(g)(4).
251 U.S. Government Accountability Office (GAO), Environmental Litigation: Information on Endangered Species Act
Deadline Suits, GAO-17-304, February 2017, at https://www.gao.gov/assets/690/683058.pdf. Hereinafter cited as
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(i.e., deadline suits). The Government Accountability Office reported that most deadline suits
from 2005 to 2015 were related to the Services missing deadlines on petitions to list species under
the ESA.252 The study found that most of the suits were resolved through settlements that
established timelines for completing the listing process.
Some stakeholders assert that deadline suits can burden the Services with heavy workloads and
influence their priorities.253 Further, some contend that deadline suit settlements may result in the
Services not fully assessing the science behind listing, potential y leading to more lawsuits in the
future.254 Other stakeholders contend, in support of citizen suit provisions, that species
languishing in the listing process for years have gained ESA protection only because successful
citizen suits forced the Services to act.255 One study reported that citizen suits drive listings of
species that may be at greater risk of extinction than those proposed by FWS.256 The same study
presented data to support the thesis that citizen proposals for listings are more likely to concern
species that generate conflict with development.257
ESA Section 8: Treaties and Conventions
Implemented by the ESA
In addition to providing for listing and protecting species, the ESA is the implementing legislation
for the Convention on International Trade in Endangered Species of Wild Fauna and Flora
(CITES) for the United States.258 It is also the implementing legislation for the Convention on
Nature Protection and Wildlife Preservation in the Western Hemisphere (the Western Hemisphere
Convention) for the United States.259
CITES
CITES is an international agreement among national governments that aims to ensure the
international trade in plants and animals does not threaten their survival. CITES provides a
framework that is voluntarily adhered to by each of the 183 signatories, or parties.260 Parties to
CITES are responsible for implementing the convention in their national legislation.261 In the

GAO, Environm ental Litigation.
252 GAO, Environmental Litigation, p. 2.
253 GAO, Environmental Litigation, p. 2.
254 GAO, Environmental Litigation, p. 2.
255 GAO, Environmental Litigation, p. 2, and E. E. Puckett, D. C. Kesler, and D. N. Greenwald, “T axa, Petitioning
Agency, and Lawsuits Affect T ime Spent Awaiting Listing Under the U.S. Endangered Species Act,” Biological
Conservation, vol. 201 (2016).
256 Berry J. Brosi and Eric G. N. Biber, “Citizen Involvement in the U.S. Endangered Species Act,” Science, vol. 337
(August 17, 2012), pp. 802-803.
257 Berry J. Brosi and Eric G. N. Biber, “Citizen Involvement in the U.S. Endangered Species Act,” Science, vol. 337
(August 17, 2012), pp. 802-803.
258 T .I.A.S. 8249, as signed by the United States, March 3, 1979. See CRS Report RL32751, The Convention on
International Trade in Endangered Species of Wild Fauna and Flora (CITES) , by Pervaze A. Sheikh.
259 50 Stat. 1354; T S 981, as signed by the United States, October 12, 1940; ESA §8(a), 16 U.S.C. §1537(a).
260 For more information, see the Convention on the International T rade in Endangered Species of Wild Fauna and
Flora (CIT ES) at https://www.cites.org/eng.
261 Resolution Conf. 8.4 (Rev. CoP15) on National Laws for Implementation of the Convention, at
https://www.cites.org/sites/default/files/document/E-Res-08-04-R15_0.pdf.
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United States, the implementing legislation for CITES is the ESA. CITES paral els the ESA’s
structure by dividing its listed species into groups according to the estimated risk of extinction.
However, rather than differentiating species as threatened or endangered, as done under the ESA,
CITES uses three major categories of protected species organized into three appendixes. Species
listed under CITES are first identified as needing protection and then assessed for the risk trade
poses for the species’ survival. Approximately 5,900 species of animals and approximately
32,000 species of plants were listed under CITES as of October 2020.
Appendix I
The most stringent restrictions on trade are for species listed in Appendix I. Appendix I contains
species that are threatened with extinction, which are or may be affected by trade. CITES
general y prohibits commercial international trade in specimens of these species. Circumstances
under which these species can be traded include scientific exchange, breeding, or educational
programs. Both an import and an export permit (or reexport certificate) are required for the
limited trade al owed for species in Appendix I.262 For example, al eight species of Pangolin, a
smal , scaly anteater living in parts of Africa and Asia, are listed in Appendix I. They were listed
in 2017 due to declines in their populations. Pangolins are considered one of the most trafficked
mammals in the world because of high demand for their scales for use in traditional Chinese
medicine and their meat, which is considered a delicacy in several countries.263
Appendix II
Appendix II contains species that are not necessarily threatened with extinction but require
controlled trade to prevent population declines. Trade in Appendix II species is less restrictive
than trade in Appendix I species, and exchange is permitted for commercial purposes if trade wil
not be detrimental to the species in the wild. Trade of Appendix II species requires only an export
permit from the country of origin, unless the importing country has imposed additional
requirements, which is al owed under CITES.264
Appendix III
Appendix III species are listed because at least one country has requested that other countries
assist it in regulating trade of that species. International trade of Appendix III species may require
one of the following three documents: (1) export permit, granted for a species coming from the
country that listed it; (2) reexport permit, granted for an Appendix III species being exported from
a country that previously imported it; or (3) certificate of origin, for Appendix III specimens that
are being exported from a country other than the listing country.265

262 A reexport certificate is granted for an Appendix I species being exported from a country that previously imported
it. For example, if the United States imported a species from Kenya, where it was listed originally, then exported the
species, a reexport permit would be necessary. T his also would include items subsequently converted to manufactured
goods.
263 United Nations Office on Drugs and Crime et al., World Wildlife Crime Report 2020: Trafficking in Protected
Species, May 2020.
264 Article IV of CIT ES.
265 Article V of CIT ES.
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CITES Implementation
In CITES, the signatory parties agreed to regulate trade through a series of import and export
permits corresponding to the degree of protection afforded the species.266 The ESA makes
violating CITES a violation of U.S. law if committed within the jurisdiction of the United
States.267 The enforcement of CITES is the responsibility of the party countries.268 CITES does
not provide any enforcement authority. Parties are required to “take appropriate measures” to
prohibit trade that violates the treaty, as wel as to provide for penalties for violations and the
confiscation and, where feasible, return of il egal y traded specimens.269
Article VIII lists other enforcement activities, including (1) designation of ports of entry and exit
for species; (2) care for living specimens; (3) maintenance of detailed rec ords on the import and
export of listed species; and (4) preparation of a biennial report on the regulatory measures taken
to enforce the treaty’s provisions. Party countries also are al owed to adopt stricter domestic
measures than provided in the convention.270 Several countries have done so, including countries
within the European Union and the United States through the enactment and implementation of
the ESA.
The administration of CITES is handled by the Secretariat, and every two to three years the
Parties convene at the Conference of the Parties (COP) to consider proposals for listing and other
actions. The Secretariat is housed within the United Nations Environment Programme in Geneva,
Switzerland, and is funded by parties through a trust fund. The Secretariat has a broad range of
duties, including organizing meetings of the parties, preparing reports on the meetings, and
publishing annual status reports. The Secretariat also is responsible for undertaking scientific and
technical studies that wil contribute toward implementing CITES. At the COP, the parties vote on
adopting amendments to Appendixes I and II, review the convention’s progress in meeting its
goals, and make recommendations for improving CITES. Taking actions on substantive proposals
or making major procedural changes usual y requires a two-thirds vote by the parties; however,
many other decisions are made by consensus.271
CITES Scientific and Management Authorities
Under CITES, each signatory agrees to designate one or more scientific authorities and
management authorities to assist with implementing and enforcing the treaty’s provisions.
Pursuant to the ESA, the Secretary of the Interior is designated as the management authority and
the scientific authority for CITES in the United States. Under the ESA, these authorities are

266 Articles III-V of CIT ES.
267 ESA §9(c), 16 U.S.C. §1538(c).
268 Article VIII of CIT ES.
269 Article VIII of CIT ES. T he parties to the convention adopted a resolution directing the Secretariat to review national
laws to assess implementation of the convention. Resolution Conf. 8.4 (Rev. CoP15) on National Laws for
Implementation of the Convention, https://cites.org/eng/res/08/08-04R15.php. T his resolution directs the Secretariat to
identify parties whose domestic measures do not (1) designate a Management and Scientific Authority (see section on
CIT ES Scientific and Management Authorities below for more information); (2) prohibit trade of species in violation of
the Convention; (3) penalize violations; and (4) authorize for the confiscation of species illegally traded or possessed.
Parties that do not have sufficient measures to implement CIT ES can be subject to a temporary suspension of trade of
CIT ES-listed species until adequate measures are enacted, according to the resolution.
270 Article VII of CIT ES.
271 GAO, Protected Species: International Convention and U.S. Laws Protect Wildlife Differently, GAO-04-964,
September 2004.
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delegated to FWS.272 The functions of scientific authorities are defined in part by CITES and the
party. Among other things, scientific authorities are required to do the following:
 Provide scientific advice and recommendations on the application of CITES
programs and documents.
 Evaluate the status of CITES-listed species within their countries and assess the
status of species listed under CITES.
 Determine whether imports or exports of species listed under CITES wil have a
harmful effect on their conservation status.
 Recommend whether import restrictions for a species should be proposed
because trade may have a negative effect on the species’ status in the wild or
because the introduction of the species into the country would present an
ecological threat to native species.273
The Secretary of the Interior is required to base import and export determinations upon “the best
available biological information,” although population estimates are not required.274
The ESA also designated the Secretary of the Interior, again exercised through FWS, as the
management authority for the United States under CITES.275 The management authority must (1)
review applications for CITES permits; (2) communicate with the Secretariat on scientific,
administrative, and enforcement issues; (3) monitor trade of species listed under CITES and
report trade and other issues to the Secretariat; and (4) represent the United States at the
Conference of the Parties.276
Convention on International Trade in Endangered Species of Wild Fauna and
Flora (CITES) and the ESA
The ESA implements CITES in the United States. The ESA and CITES lists are overlapping but not identical, with
many species included in both lists.
Although there are similarities between CITES and the ESA in listing and protecting species, several fundamental
differences exist. The ESA and CITES have similar rationales for listing species; namely, that there is a threat t o the
survival of the species. However, under CITES, this threat is specifical y associated with the harvesting of the
species or their parts for international trade, although other parameters may be considered. Under the ESA,
consideration of the threat to survival is broader and includes factors such as habitat loss, disease, and predation
in addition to trade and consumption.
Species listed under both lists do not have equal levels of protection. For example, the Saiga antelope (Saiga
tatarica mongolica) is listed under Appendix II in CITES and is listed as endangered under the ESA. These listings
carry different requirements for importing a trophy. Species that are not prohibited for trade under CITES but are
listed as threatened or endangered under the ESA can be imported to the United States if the importer meets the
requirements under Section 10 or a Section 4(d) rule (if threatened) of the ESA. For example, Section 10 permits
have been issued for the import of endangered giant pandas, cheetahs, and Asian elephants for scientific research
but general y not for incidental take.
Species do not receive equivalent protection if they are listed as endangered under the ESA versus being listed in
Appendix I of CITES. CITES al ows for the trade in endangered species, if trade is not detrimental to the species’
survival. To receive an import permit, the ESA requires that the import of the endangered species have a net
result of enhancing the survival of the species. For example, cheetahs are an Appendix I species under CITES and
are listed as endangered under the ESA. Under CITES, some countries have al owed the limited trade of sport-

272 ESA §8(a), 16 U.S.C. §1537(a).
273 50 U.S.C. §23.6.
274 16 U.S.C. §1537a(c)(2).
275 ESA §8A(a), 16 U.S.C. §1537a(a).
276 50 U.S.C. §23.6.
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hunted cheetahs, because it was shown that this trade would not be a detriment to the population. Under the
ESA, however, FWS has not issued permits for importing sport-hunted cheetah trophies, because their take has
not been shown to enhance the species’ survival in its range country.
However, both the ESA and CITES al ow limited take of endangered species in some cases where the objective is
scientific research, conservation, or education. The ESA further al ows the issuance of permits for incidental take
during otherwise lawful actions. Many have suggested these fundamental differences between regulation under
CITES and under the ESA demonstrate that the ESA is stricter than CITES with regard to species protection.
Sources: Government Accountability Office (GAO), Protected Species: International Convention and U.S. Laws Protect
Wildlife Differently, GAO-04-964, September 2004; CRS Report RL32751, The Convention on International Trade in
Endangered Species of Wild Fauna and Flora (CITES), by Pervaze A. Sheikh.
Western Hemisphere Convention
In 1942, the Convention on Nature Protection and Wild Life Preservation in the Western
Hemisphere (the Western Hemisphere Convention) entered into force.277 The convention is a
multilateral treaty that addresses trade and migratory bird protection, as wel as protection of at-
risk species and preservation of natural landscapes.278 Twenty-two countries in the Western
Hemisphere, including the United States, are signatories to the convention. The ESA implements
the convention and directs the Secretary to cooperate with the Secretary of State and other
Secretaries, as appropriate, in its implementation.279
Through the Western Hemisphere Convention, the United States aims to establish various
categories of nature reserves, regulate international wildlife trade with other signatories, and
protect wildlife. The treaty does not have monitoring requirements and requires no actions by
parties, and the parties do not meet. To some extent, the Western Hemisphere Convention’s goals
have been subsumed under those of the ESA and other international treaties, particularly with
respect to wildlife conservation.
Appropriations for the ESA
Although the ESA states that “al Federal departments and agencies shal seek to conserve
endangered species and threatened species,”280 the ESA, as noted, is primarily administered by
two agencies: FWS and NMFS. As such, these agencies receive the majority of funding
appropriated to administer the ESA, though other agencies also may receive funding for ESA-
related activities.
Not al funding for the ESA is specified as individual line items within the appropriations for
FWS or NMFS, which can make it difficult to ascertain the exact amount of funding directed to
implementing the ESA. Although the authorization for funding under the ESA expired on October

277 56 Stat. 1354; T reaty Series 981. T he treaty is located at https://www.fws.gov/migratorybirds/pdf/T reaties-
Legislation/T reay-WesternHemisphere.pdf.
278 56 Stat. 1354; T reaty Series 981.
279 ESA §8A(c); 16 U.S.C. §1537a(e).
280 16 U.S.C. §1531(c).
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1, 1992,281 Congress has appropriated funds in each succeeding fiscal year. ESA prohibitions and
penalties remain in effect regardless of the status of authorization of appropriations.282
U.S. Fish and Wildlife Service
FWS is the primary agency administering the ESA for terrestrial, freshwater, and catadromous
species. According to FWS, the agency undertakes ESA activities related to the following:
 Candidate conservation
 Consultations
 Grant making
 Habitat conservation plans
 International activities
 Listing and critical habitat
 Recovery
 Work with tribes283
FWS general y receives annual discretionary appropriations through the Interior, Environment,
and Related Agencies appropriations law for each fiscal year. The funding for FWS’s ESA-related
activities general y is provided in two accounts: the Resource Management appropriations
account and the Cooperative Endangered Species Conservation Fund (CESCF) appropriations
account (see Table 4). Within the Resource Management account, ESA-related funding is
provided under the Ecological Services activity, which addresses four sub-activities: listing,
planning and consultation, conservation and restoration, and recovery.284
Table 4. Enacted FWS Discretionary Appropriations for ESA-Related Activities,
FY2016-FY2021
(in thousands of nominal dol ars)
Fiscal Year
Ecological Services Activity
CESCF Appropriations
Within Resource Management
Account
Appropriations Account
FY2016
$234,006
$53,495
FY2017
$240,022
$53,495
FY2018
$247,825
$53,495
FY2019
$251,825
$45,995
FY2020
$266,012
$35,731
FY2021
$269,666
$30,840
Sources: CRS. Compiled from FY2016-FY2021 appropriations legislation and related reports.

281 ESA §15, 16 U.S.C. §1542. Under this section, authorizations for appropriations for the ESA are provide d to DOI,
the Department of Commerce, and the Department of Agriculture.
282 Because the authorization for appropriations expired in FY1992, it is sometimes said that the ESA is not authorized.
However, that does not mean that the agencies lack authority to conduct actions or that prohibitions within the act are
no longer enforceable; those statutory provisions would continue to be law even if no money were appropriated.
283 For more information, see FWS, “Endangered Species: Overview,” at https://www.fws.gov/endangered/about/
index.html.
284 T his organization of sub-activities began in FY2016 and continues today.
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Notes: For the Ecological Services Activity, funding levels for appropriations for the entire activity are provided.
The amounts listed under the Cooperative Endangered Species Conservation Fund (CESCF) account include
funding provided through the discretionary appropriations process and any rescissions stipulated in those
appropriations laws.
National Marine Fisheries Service
NMFS is the primary agency implementing the ESA for most marine and anadromous species.
According to NMFS, the agency’s ESA-related activities include but are not limited to the
following:
 Listing species under the ESA and designating critical habitat
 Developing protective regulations
 Developing and implementing recovery plans
 Monitoring and evaluating the status of listed species
 Providing grants to states and tribes for species conservation
 Consulting on federal actions that may affect a listed species or its designated
critical habitat
 Entering bilateral and multilateral agreements with other nations to encourage
conservation
 Issuing permits that authorize scientific research to learn more about listed
species or activities that enhance the propagation or survival of listed species285
NMFS general y receives discretionary appropriations in annual Commerce, Justice, Science, and
Related Agencies appropriations laws. NMFS’s funding for ESA activities general y is included
in two discretionary accounts within the appropriations for the National Oceanic and Atmospheric
Administration: Operations, Research, and Facilities (ORF) and the Pacific Coastal Salmon
Recovery Fund (PCSRF) (see Table 5). Within ORF, appropriations for ESA activities may be
included within multiple appropriations line items in the Protected Resources Science and
Management activity and the Enforcement activity, both of which may include non-ESA-related
funding, as wel . The PCSRF supports West Coast Pacific salmon recovery efforts by providing
grants to the states of Washington, Oregon, Idaho, Nevada, California, and Alaska and to
federal y recognized tribes of the Columbia River and Pacific Coast.286 Grants are used for the
conservation of salmon and steelhead trout populations that are listed or at risk of being listed as
threatened or endangered.
Table 5. NMFS ESA Funding for FY2016-FY2021
(in thousands of nominal dol ars)
Fiscal Year
Estimated ESA Appropriations
PCSRF
FY2016
$142,459
$65,000
FY2017
$146,160
$65,000
FY2018
$148,727
$65,000
FY2019
$153,495
$65,000

285 For more information, see NMFS, “Endangered Species Conservation,” at https://www.fisheries.noaa.gov/topic/
endangered-species-conservation.
286 16 U.S.C. §3645(d)(2).
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Fiscal Year
Estimated ESA Appropriations
PCSRF
FY2020
$156,811
$65,000
FY2021
$162,199
$65,000
Sources: CRS. Data compiled from NOAA Budget Office, emails to CRS, May 14, 2020, and March 2, 2021, and
relevant Commerce and Justice, Science, and Related Agencies Appropriations bills and reports.
Note: The Pacific Coastal Salmon Recovery Fund (PCSRF) is an appropriations account and is specified in the
annual appropriations legislation.
Concluding Remarks
The ESA and its predecessors have been in place since 1966. Since enactment, these acts have led
to the listing of more than 2,400 species as threatened or endangered, including species in the
United States and U.S. territories and in foreign countries.287 As of October 2020, 2,361 species
were listed, the majority of which (71%) were listed in the United States (the remaining 29%
were foreign species).288 Of the total, 79% were listed as endangered and 21% were listed as
threatened. (See Figure 1.)
As of October 2020, 91 species have been delisted under the ESA since it was enacted in 1973,
which is approximately 3.7% of the total number of species ever listed under the act. FWS
provided several justifications for delisting, as follows:
 Approximately 65% delisted due to recovery
 Approximately 15% delisted due to new information, changes in the law, or
improved scientific understanding of the species
 Approximately 12% deemed extinct and delisted
 Approximately 8% delisted due to scientific reclassification of the species289
Delisting a species took 25.4 years on average, though the time required ranged from 3.6 years to
52.9 years. When considering only those 59 species delisted solely due to recovery, delisting a
species took an average of 30.6 years and ranged from 8.2 years to 52.9 years. In addition, of the
currently listed species, 53 listed species have been reclassified from either endangered to
threatened (downlisted; 43 species) or from threatened to endangered (uplisted; 10 species).290
A long-standing question is whether the ESA effectively achieves its purposes as outlined in the
act. Various stakeholders have offered different interpretations on this issue. Some have offered as
evidence of the act’s success the very low rate of extinction for those species listed under the

287 T his number is based on the sum of currently listed species and those species that have been delisted. See FWS,
Environmental Conservation Online System, “Listed Species Summary (Boxscore),” as of October 23, 2020, at
https://ecos.fws.gov/ecp/report/boxscore. T his number does not account for those species listed due to “ similarity of
appearance” and includes some species that are counted more than once due to multiple listings for the same species
(e.g., those species with multiple listed distinct population segments). Also see FWS, Environmental Conservation
Online System, “Delisted Species,” at https://ecos.fws.gov/ecp/report/species-delisted. T his list may not include species
that have been delisted since the list was last updated.
288 FWS, Environmental Conservation Online System, “Listed Species Summary (Boxscore), ” as of October 2020, at
https://ecos.fws.gov/ecp/report/boxscore.
289 FWS, Environmental Conservation Online System, “Reclassified Species,” as of October 2020, at
https://ecos.fws.gov/ecp/report/boxscore. Hereinafter cited as FWS, “ Reclassified Species.”
290 FWS, “Reclassified Species.”
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ESA.291 Stakeholders routinely have supported this position by stating that since the ESA’s
enactment, less than 1% of listed species have become extinct (11 species have been delisted due
to extinction, according to FWS) or, conversely, that over 99% of listed species have successfully
been conserved. Other stakeholders have suggested the ESA has been ineffective at
conservation,292 positing that recovery is an integral component of success as presumed by the
definition of conservation included in the act—“to bring any endangered or threatened species to
the point at which the measures provided in [the ESA] are no longer necessary.”293 To support this
position, they highlight that only a smal number of species have been delisted due to recovery
(59 species, according to FWS). FWS has recognized both of the above stakeholder positions in
defining success under the ESA, while acknowledging that the ESA is “also seen as one of the
most controversial” laws.294
In addition to addressing whether the ESA has been successful at conserving species, various
stakeholders have raised numerous other issues related to the act, including the following:
 The ESA’s effects on private property and landowners295
 The ability to conserve species before it is necessary to list them296
 The cost of listing species and the resulting economic impacts297
 The availability of funding for the ESA298
 Incentives for conservation under the ESA299
 States’ role in conserving listed species
 Delays in listing, delisting, and reclassification of species under the ESA300
 Litigation related to the ESA

291 For example, see Center for Biological Diversity, “T he Endangered Species Act: A Wild Success,” at
https://www.biologicaldiversity.org/campaigns/esa_wild_success/.
292 For example, see Competitive Enterprise Institute, “Four Reasons the Endangered Species Act Desperately Needs
Reform,” August 8, 2018, at https://cei.org/blog/four-reasons-endangered-species-act-desperately-needs-reform.
293 16 U.S.C. §1532(3).
294 FWS, Endangered Species, “Defining Success Under the Endangered Species Act,” at https://www.fws.gov/
endangered/news/episodes/bu-04-2013/coverstory/index.html.
295 For example, see Jonathan Wood, Property and Environment Research Center, “Endangered Species Depend on
Private Land, So Why T reat Landowners as the Enemy?,” August 6, 2017, at https://www.perc.org/2017/08/06/
endangered-species-depend-on-private-land-so-why-treat-landowners-as-the-enemy/.
296 For example, see David Festa, Environmental Defense Fund, “T rump’s ESA Overhaul Won’t Give Americans What
T hey Want. Here’s What Will,” July 26, 2018, at http://blogs.edf.org/growingreturns/2018/07/26/trump-endangered-
species-act-overhaul-reform/.
297 For example, Robert Gordon, Competitive Enterprise Institute, “‘Whatever the Cost ’ of the Endangered Species
Act, It’s Huge,” August 21, 2018, at https://cei.org/content/whatever-cost-endangered-species-act-its-huge.
298 For example, Stephanie Kurose, “Fund Endangered Species Act, It’s Saved 99 Percent of Wildlife on the Brink,”
Hill, May 23, 2019, at https://thehill.com/opinion/energy-environment/445309-fund-endangered-species-act-its-saved-
99-percent -of-wildlife-on.
299 For example, American Farm Bureau Federation, “T he Endangered Species Act ,” at https://www.fb.org/issues/
regulatory-reform/the-endangered-species-act/https://www.fb.org/issues/regulatory-reform/the-endangered-species-act/
.
300 For example, Emily E. Puckett, Dylan C. Kesler, and D. Noah Greenwald, “T axa, Petitioning Agency, and Lawsuits
Affect T ime Spent Awaiting Listing Under the US Endangered Species Act,” Biological Conservation, vol. 201 (2016),
pp. 220-229. Also, Holly Doremus and Joel E. Pagel. “ Why Listing May Be Forever: Perspectives on Delisting Under
the U.S. Endangered Species Act ,” Conservation Biology, vol. 15, no. 5 (2001), pp. 1258-1268.
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Given the perennial nature of these issues and the controversial nature of the ESA, these issues
are routinely of concern to Members of Congress.
Author Information

Pervaze A. Sheikh
R. Eliot Crafton
Specialist in Natural Resources Policy
Analyst in Natural Resources Policy

Erin H. Ward

Legislative Attorney

Disclaimer
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under the direction of Congress. Information in a CRS Report should n ot be relied upon for purposes other
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