NatureServe GRank/SRank Codes
List Title
NatureServe Global (G) and State (S) Conservation Status Rank List
Description
Ranks for taxa occurring in national parks provided by NatureServe
Data Source
NatureServe. 2026. NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. (Accessed: March 4, 2026).
Acknowledgement
This information is provided by NatureServe (www.natureserve.org) and its network of natural heritage member programs, a leading source of information about rare and endangered species, and threatened ecosystems.
B
Breeding
Conservation status refers to the breeding population of the species in the nation or state/province.
G1
Critically Imperiled
At very high risk of extinction due to extreme rarity (often 5 or fewer populations), very steep declines, or other factors.
G2
Imperiled
At high risk of extinction due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors.
G3
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.
G4
Apparently Secure
Uncommon but not rare; some cause for long-term concern due to declines or other factors.
G5
Secure
Common; widespread and abundant.
GH
Possibly Extinct
Missing; known from only historical occurrences but still some hope of rediscovery.
GNA
Not Applicable
A conservation status rank is not applicable because the species is not a suitable target for conservation activities.
GNR
Unranked
Global rank not yet assessed.
GU
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?) to express uncertainty, or a range rank (e.g., G2G3) is used to delineate the limits (range) of uncertainty.
GX
Presumed Extinct
Not located despite intensive searches and virtually no likelihood of rediscovery.
M
Migrant
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 nation or state/province.
N
Nonbreeding
Conservation status refers to the non-breeding population of the species in the nation or state/province.
S#?
Inexact Numeric Rank
Denotes inexact numeric rank. This designation should not be used with any of the variant national or subnational conservation status ranks or NX, SX, NH, or SH.
S#S#
Range Rank
A numeric range rank (e.g., S2S3 or S1S3) is used to indicate any range of uncertainty about the status of the species or ecosystem. Ranges cannot skip more than two ranks (e.g., SU is used rather than S1S4).
S1
Critically Imperiled
At very high risk of extirpation in the jurisdiction due to very restricted range, very few populations or occurrences, very steep declines, severe threats, or other factors.
S2
Imperiled
At high risk of extirpation in the jurisdiction due to restricted range, few populations or occurrences, steep declines, severe threats, or other factors.
S3
Vulnerable
At moderate risk of extirpation in the jurisdiction due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors.
S4
Apparently Secure
At a fairly low risk of extirpation in the jurisdiction due to an extensive range and/or many populations or occurrences, but with possible cause for some concern as a result of local recent declines, threats, or other factors.
S5
Secure
At very low or no risk of extirpation in the jurisdiction due to a very extensive range, abundant populations or occurrences, with little to no concern from declines or threats.
SH
Possibly Extirpated
Known from only historical records but still some hope of rediscovery. There is evidence that the species or ecosystem may no longer be present in the jurisdiction, but not enough to state this with certainty. Examples of such evidence include (1) that a species has not been documented in approximately 20-40 years despite some searching and/or some evidence of significant habitat loss or degradation; (2) that a species or ecosystem has been searched for unsuccessfully, but not thoroughly enough to presume that it is no longer present in the jurisdiction.
SNA
Not Applicable
A conservation status rank is not applicable because the species or ecosystem is not a suitable target for conservation activities. See http://www.natureserve.org/explorer/ranking.htm for more details.
SNR
Unranked
National or subnational conservation status not yet assessed.
SU
Unrankable
Currently unrankable due to lack of information or due to substantially conflicting information about status or trends.
SX
Presumed Extirpated
Species or ecosystem is believed to be extirpated from the jurisdiction (i.e., nation, or state/province). Not located despite intensive searches of historical sites and other appropriate habitat, and virtually no likelihood that it will be rediscovered. [Equivalent to “Regionally Extinct” in IUCN Red List terminology]
T1
Critically Imperiled
At very high risk of extinction due to extreme rarity (often 5 or fewer populations), very steep declines, or other factors.
T2
Imperiled
At high risk of extinction due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors.
T3
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.
T4
Apparently Secure
Uncommon but not rare; some cause for long-term concern due to declines or other factors.
T5
Secure
Common; widespread and abundant.
TH
Possibly Extinct
Missing; known from only historical occurrences but still some hope of rediscovery
TNA
Not Applicable
TNR
Unranked
Taxonomic rank not yet assessed.
TU
Unrankable
Currently unrankable due to lack of information or due to substantially conflicting information about status or trends.
TX
Presumed Extinct
Not located despite intensive searches and virtually no likelihood of rediscovery