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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.
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. |
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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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Montana Species of Concern 
