- FEDERAL STATUS
- 1. U.S. Fish and Wildlife Service (1993a, 1993b, 1996, 2011)
- E Endangered: taxa formally listed as endangered.
- T Threatened: taxa formally listed as threatened.
- C Candidate: taxa for which the Service has on file sufficient
information on biological vulnerability and threat(s) to support
proposals to list them as endangered or threatened species.
- 2. U.S. Forest Service (USDA Forest Service 1994, 2011)
S: Sensitive: those plant and animal species identified by the Regional Forester for
which population viability is a concern as evidenced by:
a. Significant current or predicted downward trends in population numbers or density.
b. Significant current or predicted downward trends in habitat capability that would reduce a species’ existing distribution.
- 3. Bureau of Land Management (BLM 1990)
- S: Sensitive: those species found on public lands, designated by a State Director,
that could easily become endangered or extinct in a State. The protection provided for
sensitive species is the same as that provided Candidate species.
- NATURESERVE CONSERVATION STATUS RANKS (NATURAL HERITAGE RANKS)
Documentation of the methods for developing these ranks is available at
- GLOBAL RANK (G): based on range-wide status of a species
G1 Critically imperiled globally because of extreme rarity (5 or fewer occurrences, or very few remaining individuals), or because of some factor of its biology making it especially vulnerable to extinction. (Critically endangered throughout its range).
G2 Imperiled globally because of rarity (6 to 20 occurrences) or because of other factors demonstrably making it very vulnerable to extinction throughout its range. (Endangered throughout its range).
G3 Vulnerable throughout its range or found locally in a restricted range (21 to 100 occurrences). (Threatened throughout its range).
G4 Apparently secure globally, though it might be quite rare in parts of its range, especially at the periphery.
G5 Demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery.
GX Presumed extinct
GQ Indicates uncertainty about taxonomic status.
GU Unable to assign rank due to lack of available information.
G? Indicates uncertainty about an assigned global rank.
- TRINOMIAL RANK (T): used for subspecies or varieties.
- These taxa are ranked on the same criteria as G1-G5.
- STATE RANK (S): based on the status of a species in an individual state. S ranks may differ
between Colorado and neighboring states based on the relative abundance of a species in each state.
S1 Critically imperiled in state because of extreme rarity (5 or fewer occurrences, or very few remaining individuals, or because of some factor of its biology making it especially vulnerable to extirpation from the state. (Critically endangered in state).
S2 Imperiled in state because of rarity (6 to 20 occurrences) or because of other factors demonstrably making it very vulnerable to extirpation from the state. (Endangered or threatened in state).
S3 Vulnerable in state (21 to 100 occurrences).
S? Indicates uncertainty about an assigned state rank.
SH Of historical occurrence, not documented in Colorado for 20 or more years.
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