This glossary is intended to give the meaning of key words but does not necessarily provide a legal definition or thorough description. To locate the legal definitions of Endangered Species Act terms, please see the end of this document.*

Acronyms used below:
ESA – Endangered Species Act
FWS – U.S. Fish and Wildlife Service
NOAA Fisheries – National Oceanic and Atmospheric Administration B Fisheries (formerly National Marine Fisheries Service or NMFS)

• Endangered Species Act of 1973, as amended is Federal legislation that is intended to provide a means to conserve the ecosystems upon which endangered and threatened species depend and provide programs for the conservation of those species, thus preventing extinction of plants and animals. The law is administered by Interior Department's FWS and Commerce Department's NOAA Fisheries, depending on the species. Some relevant sections are:
  • Section 4: Part of the Endangered Species Act that addresses the listing and recovery of species and designation of critical habitat.
  • Section 6: Part of the Endangered Species Act that focuses on cooperation with the States and that authorizes FWS and NOAA Fisheries to provide financial assistance to States that have entered into cooperative agreements supporting the conservation of endangered and threatened species.
  • Section 7: Part of the Endangered Species Act that requires all Federal agencies, in consultation with FWS or NOAA Fisheries, to use their authorities to further the purpose of the ESA and to ensure that their actions are not likely to jeopardize the continued existence of listed species or result in destruction or adverse modification of critical habitat.
  • Section 8: Part of the Endangered Species Act that outlines the procedures for international cooperation.
  • Section 9: Part of the Endangered Species Act that defines prohibited actions, including the import and export, take, illegally taken possession of illegally taken species, transport, or sale of endangered or threatened species.
  • Section 10: Part of the Endangered Species Act that lays out the guidelines under which a permit may be issued to authorize prohibited activities, such as take of endangered or threatened species.
    • Section 10(a)(1)(A) Portion of section 10 that allows for permits for the taking of threatened or endangered species for scientific purposes or for purposes of enhancement of propagation or survival.
    • Section 10(a)(1)(B) Portion of section 10 that allows for permits for incidental taking of threatened or endangered species.
• Action: An activity or program of any kind authorized, funded, or carried out, in whole or in part, by a Federal agency in the United States or upon the high seas, such as: (a) an action intended to conserve listed species or their habitat; (b) the promulgation of a regulation; (c) the granting of a license, contract, lease, easement, right-of-way, permit, or grant-in-aid; or (d) an action directly or indirectly causing modification to the land, water, or air.
• Action area: All areas to be affected directly or indirectly by the Federal action and not merely the immediate area involved in the action.
• Biodiversity: The variety of life and its processes, including the variety of living organisms, the genetic differences among them, and the communities and ecosystems in which they occur.
• Biological assessment: A document prepared for the section 7 process to determine whether a proposed major construction activity under the authority of a Federal action agency is likely to adversely affect listed species, proposed species, or designated critical habitat.
• Biological opinion: A document stating the opinion of FWS or NOAA Fisheries on whether or not a Federal action is likely to jeopardize the continued existence of listed species or result in the destruction or adverse modification of critical habitat.
• Candidate Conservation Agreement (CCA): A voluntary agreement between FWS or NOAA Fisheries and other Federal or non-Federal landowners that identifies specific conservation measures that the participants of the agreement will undertake to conserve species covered by the agreement, none of which are listed under the Endangered Species Act, with the intention of preventing any need to list the species.
• Candidate Conservation Agreement with Assurances (CCAA): A voluntary agreement between FWS and a non-Federal property owner who agrees to manage lands or waters to remove threats to candidate or proposed species, with assurances that the property owner's conservation efforts will not result in future regulatory obligations that exceed those agreed to at the time the agreement is signed; it authorizes take through a section 10 permit if the species is later listed.
• Candidate species (candidate): A plant or animal species for which FWS or NOAA Fisheries has on file sufficient information on biological vulnerability and threats to support a proposal to list as endangered or threatened.
• CITES: The 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora, regulating or prohibiting international commerce of plant and animal species believed to be harmed by or that may be harmed by international trade. The authority to implement this is under section 8 of the ESA.
• Conference: The interagency cooperation process required for a Federal action that is likely to jeopardize the continued existence of a species proposed for listing or result in the destruction or adverse modification of proposed critical habitat.
• Conservation banking: A method used to offset impacts occurring elsewhere to the same listed species. A “bank” consists of non-Federal land containing natural resource values conserved and managed in perpetuity.
• Conservation recommendation: A suggestion that FWS or NOAA Fisheries may provide with a biological opinion describing discretionary conservation actions; it is advisory and does not carry any binding legal force.
• Conserve, conserving, and conservation: The use of methods and procedures necessary to bring any endangered or threatened species to the point at which the measures provided under the Endangered Species Act are no longer necessary; includes research, census, law enforcement, habitat acquisition and maintenance, propagation, live trapping, and transportation, and, in the extraordinary case where population pressures within a given ecosystem cannot be otherwise relieved, may include regulated taking.
• Consultation: The process required of a Federal agency under section 7 of the ESA when any activity authorized, carried out, or conducted by that agency may affect a listed species or designated critical habitat; consultation is with FWS or NOAA Fisheries and may be either informal or formal.
• Critical habitat: Specific geographic areas, whether occupied by a listed species or not, that are essential for its conservation and that have been formally designated by rule published in the Federal Register.
• Cumulative effects: For purposes of consultation under the ESA, the effects of future State or private activities not involving Federal activities that are reasonably certain to occur within the action area of an action subject to consultation. Cumulative effects are defined differently for purposes of the National Environmental Policy Act (NEPA).
• Delist: To remove an animal or plant species from the list of endangered and threatened wildlife and plants.
• Destruction or adverse modification of critical habitat: A direct or indirect alteration that appreciably diminishes the value of critical habitat for both the survival and recovery of a listed species.
• Distinct population segment (DPS): A subdivision of a vertebrate species that is treated as a species for purposes of listing under the Endangered Species Act. To be so recognized, a potential distinct population segment must satisfy standards specified in a FWS or NOAA Fisheries policy statement (See the February 7, 1996, Federal Register, pages 4722-4725). The standards require it to be separable from the remainder of and significant to the species to which it belongs.
• Ecosystem: A dynamic and interrelating complex of plant and animal communities and their associated nonliving (such as physical and chemical) environment.
• Ecosystem approach: A philosophy of resource management that focuses on protecting or restoring the function, structure, and species composition of an ecosystem, recognizing that all components are interrelated.
• Endangered species: An animal or plant species in danger of extinction throughout all or a significant portion of its range.
• Endemic species: A species native and confined to a certain region; generally used for species with comparatively restricted distribution.
• Enhancement of survival permit: A type of permit issued by the Service under the authority of section 10(a)(1)(A) of the Endangered Species Act. It allows an otherwise prohibited action that benefits the conservation of a listed species. These permits are issued as part of a Safe Harbor Agreement or Candidate Conservation Agreement with Assurances.
• Essential experimental population: An experimental population whose loss would appreciably reduce the prospect of survival of the species in the wild. All other experimental populations are "Anon-essential."
• Evolutionarily significant unit (ESU): A Pacific salmonid stock that is substantially reproductively isolated from other stocks of the same species and which represents an important part of the evolutionary legacy of the species. Life history, ecological, genetic, and other information can be used to determine whether a stock meets these two criteria. NOAA Fisheries uses this designation.
• Experimental population: A population (including its offspring) of a listed species designated by rule published in the Federal Register that is wholly separate geographically from other populations of the same species. An experimental population may be subject to less stringent prohibitions than are applied to the remainder of the species to which it belongs.
• Extinct species: A species that no longer exists. For ESA, a species currently believed to be extinct
• Extirpated species: A species that no longer survives in regions that were once part of its range, but that still exists elsewhere in the wild or in captivity.
• Federal action agency: Any department or agency of the United States proposing to authorize, fund, or carry out an action under existing authorities.
• Federal Register: The official daily publication for actions taken by the Federal government, such as Rules, Proposed Rules, and Notices of Federal agencies and organizations, as well as Executive Orders and other Presidential Documents.
• Formal consultation: The required process under section 7 of the ESA between FWS or NOAA Fisheries and a Federal agency or applicant conducted when a Federal agency determines its action is likely to adversely affect a listed species or its critical habitat; used to determine whether the proposed action is likely to jeopardize the continued existence of listed species or adversely modify critical habitat. This determination is stated in a biological opinion.
• Habitat: The place or environment where a plant or animal naturally lives and grows (a group of particular environmental conditions).
• Habitat Conservation Plan (HCP): A plan that outlines ways of maintaining, enhancing, and protecting a given habitat type needed to protect species; usually includes measures to minimize impacts, and may include provisions for permanently protecting land, restoring habitat, and relocating plants or animals to another area. Required before an incidental take permit may be issued.
• Harass: To intentionally or negligently, through act or omission, create the likelihood of injury to wildlife by annoying it to such an extent as to significantly disrupt normal behavior patterns such as breeding, feeding, and sheltering (defined by FWS regulation; NOAA Fisheries has not defined "Aharass" by regulation).
• Harm: To perform an act that kills or injures wildlife; may include significant habitat modification or degradation when it kills or injures wildlife by significantly impairing essential behavioral patterns including breeding, feeding, or sheltering.
• Historic range: The geographic area where a species was known to or believed to occur within historic time.
  Imperiled species see Species of concern
• Implementation schedule: An outline of actions, with responsible parties, estimated costs and timeframes, for meeting the recovery objectives described in a species' recovery plan.
• Incidental take: Take that results from, but is not the purpose of, carrying out an otherwise lawful activity.
• Incidental take permit: A permit issued under section 10(a)(1)(B) of the ESA to a non-Federal party undertaking an otherwise lawful project that might result in the take of an endangered or threatened species. Application for an incidental take permit is subject to certain requirements, including preparation by the permit applicant of a conservation plan, generally known as a "Habitat Conservation Plan" or "HCP."
• Incidental take statement: The part of a non-jeopardy biological opinion that estimates the amount or extent of incidental take of listed species likely to result from the action subject to consultation and exempts that take from section 9 take prohibitions. Per section 7(o)(2) of the ESA, actions that are conducted in conformance with the terms and conditions of an incidental take permit are exempt from the section 9(a)(1) prohibitions on take.
• Indirect effect: An effect caused by a proposed action that takes place later in time than the action, but is still reasonably certain to occur.
• Informal consultation: An optional process that includes all discussions, correspondence, etc., between FWS or NOAA Fisheries and the Federal agency or the designated non-Federal representative prior to formal consultation, if required.
• Interdependent action: An action that has no independent utility apart from the proposed action that is subject to consultation.
  Interrelated action An action that is part of a larger action, and that depends on the larger action for its justification.
• Interstate commerce permit: A permit issued under section 10(a)(1)(A) of the ESA that allows the transport and sale of federally listed species across state lines for scientific research and other activities benefiting the recovery of the species.
• Jeopardy biological opinion: A FWS or NOAA Fisheries section 7 biological opinion determining that a Federal action is likely to jeopardize the continued existence of a listed species or result in the destruction or adverse modification of critical habitat.
• Jeopardize the continued existence of: To engage in an action that reasonably would be expected, directly or indirectly, to reduce appreciably the likelihood of both the survival and recovery of a listed species in the wild by reducing the reproduction, numbers, or distribution of that species.
• Lead agency: An agency from among two or more agencies involved in a proposed Federal action that is assigned lead responsibility for a consultation. When a federal action involves more than one Federal agency, the agencies may coordinate to designate a lead agency for purposes of consultation with the FWS or NOAA Fisheries.
• Lead region: FWS region responsible for coordinating all actions taken to study, propose, list, conserve, and delist a species.
• Lead office: FWS field office responsible for coordinating all or most actions taken to study, propose, list, conserve, and delist a species. The lead office is given the lead responsibility over the entire range of a species, including anywhere it occurs in other regions.
• Listed species: A species, subspecies, or distinct population segment that has been added to the Federal list of endangered and threatened wildlife and plants.
• Listing: The formal process through which FWS or NOAA Fisheries adds species to the Federal list of endangered and threatened wildlife and plants.
• Listing priority: A number from 1 to 12 indicating the relative urgency for listing a plant or animal species as threatened or endangered, using criteria that reflect the magnitude and immediacy of threat to the species, as well as its relative taxonomic distinctness or isolation.
• Non-jeopardy biological opinion: A FWS or NOAA Fisheries section 7 biological opinion that determines that a Federal action is not likely to jeopardize the existence of a listed species or result in the destruction or adverse modification of critical habitat.
• Partner: Any entity who voluntarily participates with another on a project.
  Partnership An informal or formal effort by two or more partners to achieve a shared objective or complete a project.
• Permit: Permits enable the public to engage in legitimate wildlife-related activities that would otherwise be prohibited by law. Under ESA, a document issued by FWS or NOAA Fisheries under authority of section 10 of the ESA allowing an action otherwise prohibited under section 9. The FWS has two different programs that issue ESA permits. The Endangered Species Program issues ESA permits for native species (except for permits to import/export native species). The Division of Management Authority issues ESA permits for non-native species and also for the import/export of both non-native and native species. NOAA Fisheries issues ESA permits for marine species, and FWS/NOAA have joint responsibilities for some species such as sea turtles.
• Petition: A formal request from an interested individual to list, reclassify, or delist a species, or to revise critical habitat for a listed species under ESA. Critical habitat can be petitioned for designation under the Administrative Procedures Act.
• Primary constituent element: A physical or biological feature essential to the conservation of a species for which its designated or proposed critical habitat is based on, such as space for individual and population growth, and for normal behavior; food, water, air, light, minerals, or other nutritional or physiological requirements; cover or shelter; sites for breeding, reproduction, rearing of offspring, germination, or seed dispersal; and habitats that are protected from disturbance or are representative of the species' historic geographic and ecological distribution.
• Programmatic consultation: Consultation addressing multiple actions of an agency on a program-wide, regional, or other basis.
• Proposed species: A species of animal or plant that is proposed in the Federal Register to be listed under section 4 of the Endangered Species Act.
• Range: The geographic area a species is known to or believed to occupy.
• Reasonable and prudent alternative (RPA): A recommended alternative action 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 the Federal agency's legal authority and jurisdiction, that is economically and technologically feasible, and that FWS or NOAA Fisheries believes would not jeopardize the continued existence of listed species or the destruction or adverse modification of designated critical habitat.
• Reasonable and prudent measure (RPM): An action that FWS or NOAA Fisheries believes necessary or appropriate to minimize the impacts (the amount or extent) of incidental take caused by an action that was subject to consultation.
• Reclassify: To change a species' official status from threatened to endangered or vice-versa.
• Recovery: The process by which the decline of an endangered or threatened species is stopped or reversed, or threats to its survival neutralized so that its long-term survival in the wild can be ensured, and it can be removed from the list of threatened and endangered species.
• Recovery outline: The first FWS or NOAA Fisheries recovery document provided for a newly listed species. While brief, the document serves to direct recovery efforts pending the completion of the species' recovery plan.
• Recovery permit: A permit issued under section 10(a)(1)(A) of the Endangered Species Act for scientific research and other activities benefiting the recovery of federally listed species; allows for research pertaining to species recovery, such as taking blood samples from a peregrine falcon for genetic analysis, or conducting surveys of freshwater mussel beds to determine species status and distribution.
• Recovery plan: A document drafted by FWS, NOAA Fisheries, or other knowledgeable individual or group, that serves as a guide for activities to be undertaken by Federal, State, or private entities in helping to recover and conserve endangered or threatened species.
• Recovery priority: A rank, ranging from a high of 1C to a low of 18, whereby priorities are assigned to listed species and recovery tasks; assignment of rank is based on degree of threat, recovery potential, taxonomic distinctiveness, and presence of an actual or imminent conflict between the species and development activities.
• Recovery team: A group of people appointed by the lead FWS Regional Director/NOAA Assistant Administrator to guide the recovery of a listed species through such actions as developing a recovery plan or providing guidance on recovery implementation. Members of the recovery team generally include species experts from the FWS/NOAA, State governments, conservation organizations and the private sector, as well as stakeholders.
• Recovery unit: A management sub-unit of the listed entity, geographically or otherwise identifiable, that is essential to the recovery of the entire listed entity; conserves genetic or demographic robustness, important life history stages, or other feature for long-term sustainability of the entire listed entity. Recovery units are optional, but, where used, should collectively encompass the entire listed entity. Recovery criteria for the listed entity should address each identified recovery unit, and every recovery unit must be recovered before the species can be delisted.
• Rulemaking: The formal process of publishing a draft and final Federal regulation in the Federal Register; establishes a comment period for public input into the decision-making process. For example, plants and animals must be proposed for listing as threatened or endangered, and the resulting public comments must be analyzed, before the FWS or NOAA Fisheries can make a final decision.
• Safe Harbor Agreement (SHA): A voluntary agreement signed by FWS or NOAA Fisheries and a property owner and any other cooperator that (a) sets forth specific management activities that the non-Federal property owner will undertake or forgo to provide a net conservation benefit to species covered by the agreement, and (b) provides the property owner with the Safe Harbor assurances described within the agreement and authorized in an enhancement of survival permit.
• Scientific name: A formal Latin or latinized name applied to a taxonomic group of animals or plants. A species' scientific name is a two-part combination consisting of the genus followed by the species. The name is italicized or underlined. For example, the scientific name of the little brown bat is Myotis lucifugus. The genus name is Myotis, and the species name is lucifugus. If an animal species has been further divided into subspecies, or a plant species further divided into varieties, a third part is added to the scientific name. The Arizona bat is Myotis lucifugus occultus; "occultus" distinguishes the Arizona subspecies from other subspecies of the little brown bat.
• Scientific take permit: See Recovery permit.
• Section 4(d) rule: A regulation developed by FWS or NOAA Fisheries establishing prohibitions that apply for a threatened species. Any prohibitions adopted must be those necessary and advisable to provide for the conservation of the species.
• Similarity of appearance: A species may be treated as endangered or threatened if it resembles in appearance a species which has been listed under section 4 and enforcement personnel would have difficulty distinguishing between the listed and the unlisted species; if the effect of this difficulty is an additional threat to the listed species; and if such treatment of the unlisted species would improve protection for the listed species. A similarity of appearance listing must be formalized by rule.
• Special rule: See Section 4(d) rule
• Species: For purposes of the Endangered Species Act, this term includes any species or subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature.
• Species at risk: See Species of concern
• Species of concern: An informal term referring to a species that might be in need of con-servation action. This may range from a need for periodic monitoring of populations and threats to the species and its habitat, to the necessity for listing as threatened or endangered. Such species receive no legal protection and use of the term does not necessarily imply that a species will eventually be proposed for listing. A similar term is "species at risk," which is a general term for listed species as well as unlisted ones that are declining in population. Canada uses the term in its new "Species at Risk Act." “Imperiled species” is another general term for listed as well as unlisted species that are declining.
• Stakeholder: Any person or organization who has an interest in the actions discussed or is affected by the resulting outcomes of a project or action.
• Subspecies: A taxonomic rank below that of species, usually recognizing individuals that have certain heritable characteristics distinct from other subspecies of a species.
• Take: To harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct; may include significant habitat modification or degradation if it kills or injures wildlife by significantly impairing essential behavioral patterns including breeding, feeding, or sheltering.
• Terms and conditions: Required actions described in an Incidental Take Permit under section 10 or Incidental Take Statement intended to implement the Reasonable and Prudent Measures under section 7.
• Threatened species: An animal or plant species likely to become endangered within the foreseeable future throughout all or a significant portion of its range.
• Warranted but precluded: A 12-month petition finding that a petitioned action should be undertaken, but cannot because the resources necessary to do so are being devoted to actions with higher priority.

* Where to find the legal definitions:
Legal definitions can be found in the Endangered Species Act, and throughout its implementing regulations in the Code of Federal Regulations (CFR).

• Title 50 of the CFR is called Wildlife and Fisheries and its shorthand designation is written as: 50 CFR. Title 50 contains the regulations governing all programs of the U.S. Fish & Wildlife Service and NOAA Fisheries.
  • The 50 CFR is subdivided into nearly 700 parts, with each part covering a different general topic. For example, part 17 covers endangered and threatened wildlife and plants. Its shorthand designation is written as: 50 CFR 17.
    
    • Part 17 is further subdivided into sections, with each section covering a different specific topic. For example, section 3 contains definitions and its shorthand designation is written as: 50 CFR 17.3. This is just one of many sections in the 50 CFR that contain definitions.
    • The list of endangered and threatened wildlife is found at 50 CFR 17.11. The corresponding list of endangered and threatened plants is found at 50 CFR 17.12.