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National and Subnational Conservation Status Definitions
Listed below are definitions for interpreting NatureServe conservation status ranks at the national (N-rank) and subnational (S-rank) levels. The term "subnational" refers to state or province-level jurisdictions (e.g., California, Ontario).
Assigning national and subnational conservation status ranks for species and ecological communities follows the same general principles as used in assigning global status ranks. A subnational rank, however, cannot imply that the species or community is more secure at the state/province level than it is nationally or globally (i.e., a rank of G1S3 cannot occur), and similarly, a national rank cannot exceed the global rank. Subnational ranks are assigned and maintained by state or provincial natural heritage programs and conservation data centers.
National (N) and Subnational (S) Conservation Status Ranks
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Status
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Definition
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NX
SX
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Presumed
Extirpated—Species or community is believed to be extirpated from the 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.
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NH
SH
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Possibly
Extirpated (Historical)—Species or community occurred historically in the nation or state/province, 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 NH or 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 NH or 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.
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N1
S1
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Critically
Imperiled—Critically imperiled in the nation or state/province because of extreme rarity (often 5 or fewer occurrences) or because of some factor(s) such as very steep declines making it especially vulnerable to extirpation from the state/province.
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N2
S2
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Imperiled—Imperiled in the nation or state/province because of rarity due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors making it very vulnerable to extirpation from the nation or state/province.
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N3
S3
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Vulnerable—Vulnerable in the nation or state/province due to a restricted range, relatively few populations (often 80 or fewer), recent and widespread declines, or other factors making it vulnerable to extirpation.
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N4
S4
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Apparently
Secure—Uncommon but not rare; some cause for long-term concern due to declines or other factors.
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N5
S5
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Secure—Common, widespread, and abundant in the nation or state/province.
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NNR
SNR
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Unranked—Nation or state/province conservation status not yet assessed.
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NU
SU
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Unrankable—Currently unrankable due to lack of information or due to substantially conflicting information about status or trends.
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NNA
SNA
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Not
Applicable —A conservation status rank is
not applicable because the species is not a
suitable target for conservation activities.
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N#N#
S#S#
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Range
Rank —A numeric range rank (e.g., S2S3)
is used to indicate any range of uncertainty
about the status of the species or community.
Ranges cannot skip more than one rank (e.g.,
SU is used rather than S1S4).
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Not
Provided
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Species
is known to occur in this nation or state/province.
Contact the relevant natural heritage program
for assigned conservation status.
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Contact
information for individual natural heritage programs
is available at
http://www.natureserve.org/visitLocal/index.jsp.
Breeding Status Qualifiers
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Qualifier
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Definition
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B
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Breeding—Conservation status refers to the breeding population of the species in the nation or state/province.
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N
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Nonbreeding—Conservation
status refers to the non-breeding population
of the species in the nation or state/province.
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M
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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.
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Note:
A breeding status is only used for species that have distinct breeding and/or non-breeding populations in the nation or state/province. A breeding-status S-rank can be coupled with its complementary non-breeding-status S-rank if the species also winters in the nation or state/province, 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").
Other
Qualifiers
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Rank
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Definition
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?
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Inexact
or Uncertain—Denotes inexact or uncertain numeric rank. (The ? qualifies the character immediately preceding it in the S-rank.)
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