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Endangered vs.Threatened

A species can be listed and thereby made
eligible for the protections of
the ESA if it is determined by FWS
(or NMFS) to be either “endangered”
or “threatened.”
An “endangered” species is defined by the ESA as a “species which is in danger of extinction throughout all or a significant portion of its range.”
To understand this definition, it is essential to understand how “species” is defined, what it means to be “in danger of extinction,” and what a “significant portion” of a species’ range is.
“Species” is defined to include “any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature.” Thus, something less that an entire species can be listed as “endangered.” Any “subspecies,” as defined by the taxonomists, and any “distinct population segment” of vertebrate fish or wildlife, can be listed if it satisfies the criteria of what it means to be “endangered.”
What it means to be “in danger of extinction”is not defined by the ESA. It has also not been defined by regulation. There is no one-size-fits all definition that could be uniformly applied across all species. What it means to be “in danger of extinction”—i.e., the precise combination of facts that will add up to a finding of endangerment–varies from species to species, and is dependent on the unique life history and ecology of the species, the nature of the threats it faces, and its ability to respond to the threats. FWS’s listing decisions are therefore necessarily “contextual and fact-dependent,” rather than mere rote applications of the law.
FWS has stated in court that implicit in all of its listing decisions is a general understanding that “in danger of extinction” means “currently on the brink of extinction in the wild.” Thus, there is a crucial temporal component to the phrase “in danger of extinction.” To FWS, the phrase “clearly connotes an established, present condition,” as opposed to “a predicted or expected future condition.”FWS has further stated that:
to be currently on the brink of extinction in the wild does not necessarily mean that extinction is certain or inevitable, or even that it is more likely than not. Rather, a species can be on the brink of extinction indefinitely without becoming extinct. Ultimately, whether a species is currently on the brink of extinction in the wild, and the timing of the extinction event itself, depends on the life history and ecology of the species, the nature of the threats, and the species’ response to those threats.
FWS has also identified four fact patterns, which it calls Categories, that typically add up to a finding of “endangerment.”
Category 1– Category 1 consists of species that face a catastrophic threat from which the risk of extinction is imminent and certain.
FWS considers a catastrophic threat to be an event or condition, natural or man-caused, that is both imminent and certain and that will result in the complete extinction of a species. In such situations, due to the severity, certainty, and timing of the threat, other considerations are largely irrelevant.
Category 2 – Category 2 consists of species that are narrowly restricted endemics that, as a result of their limited range or population size, are vulnerable to extinction from elevated threats.
For purposes of this category, an endemic is a species that is rare in its natural state –i.e., a species that in its natural state consists of a very small population and/or inhabits a very small range. Due to its rarity, or the restricted limit of its range, such a species can be vulnerable to extinction as a result of exposure to even a small increase or change in the nature of the threats it is facing.

Category 3 – Category 3 consists of species that were formerly widespread in their distribution, but that have been reduced to such critically low numbers or restricted ranges that they are at a high risk of extinction due to threats that would not otherwise have imperiled the species.
This category applies to species that were at one time quite abundant in their natural state across a large range, but that have been reduced to such small numbers, or such a limited range, that they now face a high risk of extinction from threats that would not normally have imperiled their existence in their former state. Put another way, this category applies to species that have become, in effect, “narrowly restricted endemics.”FWS describes the species that have fallen into this category as species that have “suffered [such] catastrophic range reductions and population crashes that … their extinction seems all but certain,” or as species whose “distributions and populations [have been] so severely curtailed that on-going threats and chance events [have] resulted in them being currently on the brink of extinction.”
Category 4– Category 4 consists of species with relatively widespread distribution that have nevertheless suffered, or are suffering, major reductions in their numbers, range, or both, as a result of factors that have not been abated.
This category applies to species that still inhabit a relatively wide range, and may still consist of a large population, but which have suffered such significant reductions in their numbers or range from conditions that still persist that it is likely that if those conditions go unabated, the species will become extinct.
FWS explains that “[t]hreatened species typically have some of the characteristics of the fourth category …, in that they too have generally suffered some recent decline in numbers, range, or both, but to a less severe extent than endangered species.” “Whether a species [that falls into Category 4] is ultimately an endangered species or a threatened species depends on the specific life history and ecology of the species, the nature of the threats, and population numbers and trends,” and that “[e]ven species that have suffered fairly substantial declines in numbers or range are sometimes listed as threatened rather than endangered,” depending on other relevant factors.

A species is “endangered” if it is “in danger of extinction throughout all or a significant portion of its range.” What constitutes a “significant portion” of a species’ range is not defined by the ESA or in its implementing regulations, and it has been the subject of considerable controversy.
In December 2011, FWS and NMFS published a “Draft Policy on Interpretation of the Phrase “Significant Portion of its Range in the Endangered Species Acts’ Definitions of “Endangered Species” and “Threatened Species.” 76 FR 76987. While the Draft Policy has not been adopted in final form, it provides the best indication available of how FWS and NMFS view the issue.
The Draft Policy has four components.
First, it defines “significant as follows: A portion of the range of a species is ‘significant’ if its contribution to the viability of the species is so important that without that portion, the species would be in danger of extinction.
Second, it defines “range” as follows: The range of a species is considered to be the general geographical area within which that species can be found at the time FWS or NMFS makes any particular status determination. …. Lost historical range is relevant to the analysis of the status of the species, but it cannot constitute a significant portion of a species’ range.
Third, it reconciles the “significant portion of the range” language with the authority to list “distinct population segments” as follows: If the species is not endangered or threatened throughout all of its range, but it is endangered or threatened within a significant portion of its range, and the population in that significant portion is a valid “distinct population segment,” FWS and NMFS will list the “distinct population segment” rather than the entire taxonomic species or subspecies.
Fourth, it states that the “phrase ‘significant portion of its range’ … provides an independent basis for listing: thus there are two situations (or factual bases) under which a species would qualify for listing: a species may be endangered or threatened throughout all of its range; or a species may be endangered or threatened in only a significant portion of its range.” “If a species is found to be endangered or threatened in only a significant portion of its range, the entire species is listed as endangered or threatened , respectively, and the Act’s protections apply across the species’ entire range.”
A species is “threatened” if it “is likely to become an endangered species with the foreseeable future throughout all or a significant portion of its range.” Thus, there is significant overlap between the definition of “endangered” and the definition of “threatened” The only difference is that to be “endangered,” a species must be “in danger of extinction” now, while to be “threatened,” a species must be likely to become “in danger of extinction” in the “foreseeable future.”
Neither the ESA nor its implementing regulations defines what is meant by the “foreseeable future.” However, a January 16, 2009 M-Opinion (M-37021) by the Solicitor of the Department of the Interior provides detailed guidance. Click here for the M-Opinion.
The Guidance states that the following principles, among others, should govern FWS’s determination of the “foreseeable future”:
1. The “foreseeable future” is to be determined on the facts applicable to the species being considered for listing.
2. FWS has broad discretion in determining the “foreseeable future” for a particular species.
3. The determination must be based on the best scientific and commercial data available concerning the future population trends and threats to the species.
4. The determination must be based on the reliable predictions that can be made from the data, and not on speculation. “Reliable” does not mean “certain”; it means sufficient to provide a reasonable degree of confidence in the prediction, in light of the conservation purposes of the ESA.
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