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BC Conservation Status Ranks

Last updated on June 24, 2026

BC conservation status ranks reflect the risk of extirpation of species and ecological communities that occur in B.C. and can inform conservation action and natural resource decision making.

The BC Conservation Data Centre (BC CDC) conducts conservation status assessments to determine conservation status ranks. Lower numeric ranks indicate higher risk of extirpation relative to higher ranks. For example, a species ranked S1 is more at risk of extirpation than a species ranked S2.

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Conducting conservation status assessments

We assess the conservation status of species and ecological communities by evaluating their rarity, trends in rarity and condition, and the specific threats they face. We follow conservation status assessment methodology and standards established by NatureServe – a network of professionals who use science inform conservation.

Assessments occur on a rotating basis. Given the large number of species and ecological communities, we assess a limited number of groups each year. As a result, there may be a gap of several years between reassessment of any given species or ecological community.

The conservation status ranks of some species groups are provided by the national General Status Program.

Conservation status ranks form the basis of the BC Red, Blue, and Yellow list. However, not all species and ecological communities are assigned to one of these lists. For example, some species may be designated as “Not Reviewed” until their conservation status rank provided by the General Status program has been reviewed. Other species not listed include introduced or exotic species, as well as those with a high level of uncertainty in their conservation status. Read about the BC Red, Blue, and Yellow List.
 

Access and learn about conservation status ranks

Use BC Species & Ecosystem Explorer to find conservation status ranks of species and ecological communities in B.C. The prefix to the number rank indicates the geographic level at which the rank is applied. Learn what the ranks mean below.

 

Type of Rank

 Definition
S Subnational ranks assigned and maintained by the B.C. Conservation Data Centre
N National ranks assigned by national and international conservation authorities
G Global ranks assigned by national and international conservation authorities
View the complete list of NatureServe ranks
 
Rank Definition
X Presumed extirpated
H Historical (species) / possibly extirpated (ecological communities)
1 Critically imperiled
2 Imperiled
3 Special concern, vulnerable to extirpation or extinction
4 Apparently secure, with some cause for concern
5 Demonstrably widespread, abundant and secure
NA Not applicable
NR Not yet assessed
U Unrankable
## Range Rank—Used to indicate the range of uncertainty about conservation status (e.g. S2S3) For further information about these uncertainty rank modifiers see explanation below
? Inexact or Uncertain—Denotes inexact or uncertain numeric rank
View the complete list of NatureServe ranks

How is uncertainty expressed in ranks?

Point Spread DiagramOpen image in new window

What do the ranges and question marks mean? This graphic shows examples of how we arrive at the various conservation status ranks depending on the results obtained when applying the values to each of the factors. Conservation status assessments often include one or more status factors that are assigned a range of values to capture uncertainty, due to information that is not precise enough to allow the selection of a single value. In these cases, the low and high values of the range rating are carried through all steps in the assessment process, resulting in a range in calculated status rank. In these cases, the low and high scores at the ends of the range are evaluated according to the point spread criteria in the first column of the table to determine the final calculated conservation status rank. 

 

 

Why do conservation status ranks change?

Changes in conservation status rank may reflect real increases or decreases in the risk of extirpation due to factors such as population trends, habitat loss, or recovery efforts. However, a change in conservation status rank doesn’t always mean a species or ecological community is more, or less, at risk of extirpation. Rank shifts can occur for reasons unrelated to the actual condition, including:

  • Improved Knowledge: New inventories or research can uncover information that already existed but was previously unknown, leading to a revised understanding of a conservation status.
  • Taxonomic Updates: Changes in classification—such as splitting one species into several or lumping multiple species together—can alter how ranks are assigned.
  • Methodology Changes: Updates to NatureServe’s ranking criteria (e.g., factor weighting) may result in rank adjustments.

 

The BC Red, Blue and Yellow List simplifies the conservation status rank to a three-colour scale, where Red is the most at risk, followed by Blue, and then Yellow.

Data about species and ecosystems in B.C. can be found using these online tools:

Contact information

Please contact the Conservation Data Centre for more information.

Office
250-356-0928
Email
cdcdata@gov.bc.ca