Heritage Rank Definitions

The Alabama Natural Heritage Program uses the Heritage ranking system developed by NatureServe and the Natural Heritage Program Network. Each element is assigned two ranks; one representing its range-wide or global status (G rank), and one representing its status in the state (S rank). Element ranks are based on many factors, the most important ones being estimated number of element occurrences, estimated abundance (number of individuals for species; area for natural communities), range, estimated adequately protected EOs, relative threat of destruction, and ecological fragility. Species with a rank of 1 are most critically imperiled; those with a rank of 5 are most secure.

Global Rank Definitions

Basic Ranks

GXPresumed 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.
GHOf historical occurrence throughout its range.
Possibly Extinct (species) - Missing; known from only historical occurrences but still some hope of rediscovery.
Presumed Eliminated - (Historic, 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.
G1Critically Imperiled - At very high risk of extinction due to extreme rarity (often 5 or fewer populations), very steep declines, or other factors.
G2Imperiled - At high risk of extinction due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors.
G3Vulnerable - At moderate risk of extinction due to a restricted range, relatively few populations (often 80 or fewer), recent and widespread declines, or other factors.
G4Apparently Secure - Uncommon but not rare; some cause for long-term concern due to declines or other factors.
G5Secure - Common; widespread and abundant.

Variant Ranks

G#G#Range Rank - A numeric range rank (e.g., G2G3) is used to indicate the range of uncertainty in the status of a species or community. A G2G3 rank would indicate that there is a roughly equal chance of G2 or G3 and other ranks are much less likely. Ranges cannot skip more than one rank (e.g., GU should be used rather than G1G4).
GUUnrankable - Currently unrankable due to lack of information or due to substantially conflicting information about status or trends.
GNRGlobal rank not yet assessed.
G#T#Infraspecific Taxon (trinomial) - The status of infraspecific taxa (subspecies or varieties) are indicated by a "T-rank" following the species' global rank. Rules for assigning T-ranks follow the same principles outlined above for global conservation status ranks. A T-rank cannot imply the subspecies or variety is more abundant than the species as a whole-for example, a G1T2 cannot occur. At this time, the T rank is not used for ecological communities.
GNANot Applicable - A conservation status rank is not applicable because the species is not a suitable target for conservation activities.

Rank Qualifiers

?Inexact Numeric Rank - Denotes some uncertainty about the numeric rank (e.g. G3? - Believed most likely a G3, but some chance of either G2 or G4).
QQuestionable 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.
CCaptive or Cultivated Only - At present extant only in captivity or cultivation, or as a reintroduced population not yet established.

State Ranking Definitions

SXPresumed Extirpated - Species or community is believed to be extirpated from Alabama. Not located despite intensive searches of historical sites and other appropriate habitat, and virtually no likelihood that it will be rediscovered.
SHHistorical (Possibly Extirpated) - Species or community occurred historically in Alabama, and there is some possibility that it may be rediscovered. 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 a nation or state/province 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.
S1Critically imperiled in Alabama because of extreme rarity (5 or fewer occurrences of very few remaining individuals or acres) or because of some factor(s) making it especially vulnerable to extirpation from Alabama.
S2Imperiled in state because of rarity (6 to 20 occurrences or few remaining individuals or acres) or because of some factor(s) making it very vulnerable to extirpation from Alabama.
S3Rare or uncommon in Alabama (on the order of 21 to 100 occurrences).
S4Apparently secure in Alabama, with many occurrences.
S5Demonstrably secure in Alabama and essentially "ineradicable" under present conditions.
SNRUnranked - State conservation status not yet assessed.
SUUnrankable - Currently unrankable due to lack of information or due to substantially conflicting information about status or trends.
SNANot Applicable - A conservation status rank is not applicable because the species is not a suitable target for conservation activities.
SAAccidental in Alabama, including species (usually birds or butterflies) recorded once or twice or only at very great intervals, hundreds or even thousands of miles outside their usual range; a few of these species may even have bred on the one or two occasions they were recorded.
SEAn exotic established in Alabama.

Breeding Status Qualifiers for Migrants

BRegularly occurring, migratory and present only during the breeding season. A rank of S3B indicates a species uncommon during the breeding season (spring/summer) in Alabama.
NRegularly occurring, usually migratory and typically non-breeding species in Alabama; this category includes migratory birds, bats, sea turtles, and cetaceans which do not breed in Alabama but pass through twice a year or may remain in winter. A rank of S2B,S5N indicated a rare breeder but a common winter resident.
MMigrant - 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.

Note: Species that have resident breeding populations that are augmented in winter by non-breeding migrants may have dual ranks, one each for the breeding (B) and non-breeding (N) components. A breeding status is only used for species that have distinct breeding and/or non-breeding populations in Alabama. A breeding-status S-rank can be coupled with its complementary non-breeding-status S-rank if the species also winters in Alabama, and/or a migrant-status S-rank if the species occurs regularly on migration at particular staging areas or concentration spots where the species might warrant conservation attention. The two (or rarely, three) status ranks are separated by a comma (e.g., "S2B,S3N" or "SHN,S4B,S1M").

Last Updated: Nov 11, 2010