Species of Concern Definitions
SPECIES OF CONCERN TERMS & DEFINITIONS


Montana Species of Concern

The term "Species of Concern" includes taxa that are at-risk or potentially at-risk due to rarity, restricted distribution, habitat loss, and/or other factors. The term also encompasses species that have a special designation by organizations or land management agencies in Montana, including: Bureau of Land Management Special Status and Watch species; U.S. Forest Service Sensitive and Watch species; U.S. Fish and Wildlife Service Threatened, Endangered and Candidate species.

Status Ranks (Global and State)

The international network of Natural Heritage Programs employs a standardized ranking system to denote global (G -- range-wide) and state status (S) (NatureServe 2003). Species are assigned numeric ranks ranging from 1 (critically imperiled) to 5 (demonstrably secure), reflecting the relative degree to which they are “at-risk”. Rank definitions are given below. A number of factors are considered in assigning ranks -- the number, size and distribution of known “occurrences” or populations, population trends (if known), habitat sensitivity, and threat. Factors in a species’ life history that make it especially vulnerable are also considered (e.g., dependence on a specific pollinator).

For example, Clustered lady's slipper (Cypripedium fasciculatum) is ranked G4 S2. Globally the species is apparently secure, while in Montana it is imperiled because of rarity, or because of other factors making it demonstrably vulnerable to extirpation.

RANKS
Code
Definition
G1 S1
At high risk because of extremely limited and/or rapidly declining numbers, range, and/or habitat, making it highly vulnerable to global extinction or extirpation in the state.
G2 S2
At risk because of very limited and/or declining numbers, range, and/or habitat, making it vulnerable to global extinction or extirpation in the state.
G3 S3
Potentially at risk because of limited and/or declining numbers, range, and/or habitat, even though it may be abundant in some areas.
G4 S4
Uncommon but not rare (although it may be rare in parts of its range), and usually widespread. Apparently not vulnerable in most of its range, but possibly cause for long-term concern.
G5 S5
Common, widespread, and abundant (although it may be rare in parts of its range). Not vulnerable in most of its range.
 
OTHER CODES AND MODIFERS
Code
Definition
X
 Presumed Extinct—Species believed to be extinct throughout its range. Not located despite intensive searches of historical sites and other appropriate habitat, and virtually no likelihood that it will be rediscovered.
H
 Possibly Extinct—Species known from only historical occurrences, but may nevertheless still be extant; further searching needed.
U
 Unrankable—Species currently unrankable due to lack of information or due to substantially conflicting information about status or trends.
HYB
 Hybrid—Entity not ranked because it represents an interspecific hybrid and not a species.
##
 Range Rank—A numeric range rank (e.g., G2G3) used to indicate uncertainty about the exact status of a taxon.
T
 Infraspecific Taxon (trinomial) —The status of infraspecific taxa (subspecies or varieties) are indicated by a "T-rank" following the species' global rank.
?
 Inexact Numeric Rank—Denotes inexact numeric rank
Q
 Questionable taxonomy that may reduce conservation priority—Distinctiveness of this entity as a taxon at the current level is questionable; resolution of this uncertainty may result in change from a species to a subspecies or hybrid, or inclusion of this taxon in another taxon, with the resulting taxon having a lower-priority (numerically higher) conservation status rank.
C
 Captive or Cultivated Only—Species at present is extant only in captivity or cultivation, or as a reintroduced population not yet established.
A
 Accidental—Species is accidental or casual in Montana, in other words, infrequent and outside usual range. Includes species (usually birds or butterflies) recorded once or only a few times at a location. A few of these species may have bred on the one or two occasions they were recorded.
Z
 Zero Occurrences—Species is present but lacking practical conservation concern in Montana because there are no definable occurrences, although the taxon is native and appears regularly in Montana.
P
 Potential—Potential that species occurs in Montana but no extant or historic occurrences are accepted.
R
 Reported—Species reported in Montana but without a basis for either accepting or rejecting the report, or the report not yet reviewed locally. Some of these are very recent discoveries for which the program has not yet received first-hand information; others are old, obscure reports.
SYN
 Synonym—Species reported as occurring in Montana, but the Montana Natural Heritage Program does not recognize the taxon; therefore the species is not assigned a rank.
*
 A rank has been assigned and is under review. Contact the Montana Natural Heritage Program for assigned rank.
B
 Breeding—Rank refers to the breeding population of the species in Montana.
N
 Nonbreeding—Rank refers to the non-breeding population of the species in Montana.
 
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