A guide to regulatory status and rarity ranking codes

Introduction

This guide provides summary explanations of endangerment categories used by the U.S. Fish and Wildlife Service and the Oklahoma Department of Wildlife Conservation to designate the status of federal and state threatened or endangered or candidate species.

Prepared by the staff of the Oklahoma Natural Heritage Inventory, the guide also includes rarity rankings for plant and animals species and ecological communities in Oklahoma. These rankings have no regulatory stature: we use them to help decide priorities for biological research and for recommending species and communities for conservation in the state. Rarity ranks provide an index of the biological conservation status for species and natural communities in Oklahoma.

Federal and State Endangered Species Categories

The following status categories are utilized by the U.S. Fish and Wildlife Service and Oklahoma Department of Wildlife Conservation, respectively.

U.S. Fish and Wildlife Species Endangerment Categories

Status	Description
LE	Listed endangered
LT	Listed threatened
PE	Proposed endangered
PT	Proposed threatened
EX	Believed to be extirpated in Oklahoma
SA	Endangered or threatened due to similarity of appearance to other listed species.
C	Candidate (The Service has enough information to list species as threatened or endangered, but this action is precluded by other listing activities)

Oklahoma Department of Wildlife Conservation Species Endangerment Categories

Status	Description
LE	Listed endangered
LT	Listed threatened

Global and State Rarity Ranking

Species and natural communities occurring in Oklahoma receive two ranks: a global (G) rank reflecting its rarity throughout the world (assigned by NatureServe) and a state (S) rank reflecting its rarity within Oklahoma (assigned by ONHI biologists). Taken together, these ranks serve as an index of biological status, but the ranks are subject to change with new information. Natural Heritage rarity rankings have no regulatory stature: they are intended for information only.

Global and State Rank Categories

Rank	Description
GX SX	Presumed extinct (species): Not located despite intensive searches and virtually no likelihood of rediscovery. Eliminated (ecological communities): Eliminated throughout its range, with no restoration potential due to extinction of dominant or characteristic species.
GH SH	Possibly extinct or extirpated (species): Missing; known from only historical occurrences but still some hope of rediscovery. Presumed eliminated: (Historical, ecological communities)-Presumed eliminated throughout its range, with no or virtually no likelihood that it will be rediscovered, but with the potential for restoration, for example, American Chestnut (Forest). Its presence may not have been verified in the past 20-40 years. A species or community could become SH without such a 20-40 year delay if the only known occurrences in the state were destroyed or if it had been extensively and unsuccessfully looked for. The SH rank is reserved for species or communities for which some effort has been made to relocate occurrences, rather than simply using this status for all elements not known from verified extant occurrences.
G1 S1	Critically imperiled: At very high risk of extinction due to extreme rarity (often 5 or fewer populations), very steep declines, or other factors such as very steep declines, making it especially vulnerable to extirpation from the state.
G2 S2	Imperiled: At high risk of extinction due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors making it especially vulnerable to extirpation from the state.
G3 S3	Vulnerable: At moderate risk of extinction due to a restricted range, relatively few populations (often 80 or fewer), recent and widespread declines, or other factors making it vulnerable to extirpation.
G4 S4	Apparently secure: Uncommon but not rare; some cause for long-term concern due to declines or other factors.
G5 S5	Secure: Common; widespread and abundant.
G#G# S#S#	Range rank: A numeric range rank (e.g., G2G3; S2S3) is used to indicate the range of uncertainty in the status of a species or community. Ranges cannot skip more than one rank (e.g., GU or SU should be used rather than G1G4 or S1S4).
GU SU	Unrankable: Currently unrankable due to lack of information or due to substantially conflicting information about status or trends. Whenever possible, the most likely rank is assigned and the question mark qualifier is added (e.g., G2?; S2?) to express uncertainty, or a range rank (e.g., G2G3; S2S3) is used to delineate the limits (range) of uncertainty.
GNR SNR	Unranked: Global or state rank not yet assessed.
GNA SNA	Not applicable: A conservation status rank is not applicable because the species is not a suitable target for conservation activities.
?	Inexact or uncertain numeric rank: Denotes inexact numeric rank (e.g., G2?; S2?).
Q	Questionable taxonomy: Taxonomic distinctiveness of this entity at the current level is questionable; resolution of this uncertainty may result in change from a species to a subspecies or hybrid, or the inclusion of this taxon in another taxon, with the resulting taxon having a lower-priority conservation priority.
C	Captive or cultivated only: At present extant only in captivity or cultivation, or as a reintroduced population not yet established.
B	Breeding (state only): Conservation status refers to the breeding population of the species in the state.
N	Nonbreeding (state only): Conservation status refers to the non-breeding population of the species in the state.
M	Migrant (state only): Migrant species occurring regularly on migration at particular staging areas or concentration spots where the species might warrant conservation attention. Conservation status refers to the aggregating transient population of the species in the state.
T	Infraspecific taxon (trinomial; global only): The status of infraspecific taxa (subspecies or varieties) are indicated by a "T-rank" following the species' global rank.