Rarity Ranking Definitions

Four rarity rankings are provided for each species where available and general ranking descriptions, including from Harms (2003) and COSEWIC (year 2006), are provided below.

Harms' Ranking System Based on: V. Harms (2003). Checklist of the Vascular Plants of Saskatchewan and the Provincially and Nationally Rare Native Plants in Saskatchewan. Extension Division, University of Saskatchewan.

Vern Harms is a well-known taxonomist in Canada. He is an Emeritus professor in the Department of Biology at the University of Saskatchewan and a previous curator of SASK Herbarium. He developed the "Checklist of the Vascular Plants of Saskatchewan and the Provincially and Nationally Rare Native Plants in Saskatchewan," in which he ranks plant species according to their rarity. His opinion is highly regarded among the members of the plant community and thus, his rankings are used in our Virtual Gallery of Species at Risk in Saskatchewan.

EXT?: Species ranked as extirpated have been previously recorded in the province but apparently no longer exist here.

END: Endangered species are critically threatened by human or natural processes throughout their entire range in Saskatchewan. There are usually less than five known sites in the province. At each site, the plants are locally sparse.

THR: Species that are threatened are imperiled by their rarity and are likely to become provincially endangered. There are between six and 15 localities of these species in Saskatchewan and plants are locally sparse at most of them.

VUL: Vulnerable species are at risk of because of low or declining numbers. There is no immediate endangerment to these species. Typically, there are between 16 and 25 known sites in Saskatchewan.
Nature Conservancy Ranking (Nature Conservancy - National Ranking; Saskatchewan Conservation Data Centre - Provincial Ranking)

The Nature Conservancy of Canada is a non-profit organization that is dedicated to the protection of biodiversity in Canada. Founded over 40 years ago, the Nature Conservancy acquires ecologically significant land through purchase, donation, or conservation easement to protect plant and animal species by preserving intact landscapes. Since 1962, Nature Conservancy has protected over 1.9 million acres of land. The Nature Conservancy provides the national and global ranking given below.

The Saskatchewan Conservation Data Centre, which was formed as a co-operative venture between Saskatchewan Environment and the Nature Conservancy, is now a partnership between Saskatchewan Environment and Nature Saskatchewan. Their mission is to gather, interpret, and distribute standardized information on the status of wild species and their communities. Their provincial rankings are provided below.

Example of a Nature Conservancy ranking: G5 N4 S2

G: Global
N: National
S: Provincial
T: Infraspecific taxa (subspecies or variety) rank
X: This symbol indicates that the species has been extirpated from a region or is extinct.
H: Only historical records of this species exist in the area and there has been no recent verification.
1: These species are critically imperiled because of extreme rarity or due to some factor of their biology or environment that make it vulnerable to extirpation or extinction. There are five or fewer occurrences, or very few (less than 1,000) individuals remaining.

2: Species ranked 2 are imperiled because of rarity of due to some factor of their biology of environment that make it vulnerable to extirpation or extinction. There are between six and 20 occurrences, or few remaining individuals (1,000 to 3,000).

3: These species are vulnerable because they are either very rare and local throughout their range, are found only within a restricted range, or are threatened by some factor of their biology or environment. When found within a restricted range, these plants may be abundant in some locations. These plants are generally rare to uncommon with between 21 and 100 occurrences or between 3,000 and 10,000 plants.

4: Species with this ranking are apparently secure. They may be rare in parts of their range, for example the periphery, but are generally uncommon and widespread. Although there is no cause for immediate concern, there is a possibility for long term concern. There are more than 100 occurrences and greater than 10,000 plants.

5: These species are secure because they are widespread and abundant. They may be rare in parts of their range but in general are very common. There are well over 100 occurrences and far greater than 10,000 plants.

?: A question mark indicates that this species is unranked at that particular level.

Q The taxonomy of these species is questionable and must be resolved before the species can be ranked.

U: These species are unrankable because of a lack of information or conflicting reports.

COSEWIC Ranking (National Ranking)

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of Canadian species, subspecies, and varieties of plants and animals that may be at risk of extinction or extirpation. The knowledge used to assign rankings is based on science as well as Aboriginal and community knowledge. The evaluation process of each species is independent and transparent. The Species at Risk Act (SARA) established in 2003 designated COSEWIC as an advisory body.

The COSEWIC ranking definitions are provided below: (http://www.cosewic.gc.ca/eng/sct0/index_e.cfm)

REP: For these species, a report is or has been prepared and the ranking is pending.

EXT?: These species have been previously recorded but apparently have been extirpated from Canada.

END: Endangered species are critically threatened and are in immediate danger of extirpation throughout all of their range in Canada. Extreme rarity of these species is primarily attributed to human activity.

THR: Threatened species are imperiled because of their rarity and are likely to become endangered in Canada if the factors causing their decline are not reversed. SPC: Species of special concern are at risk because of low or declining numbers but face no obvious or immediate threats.


NAR: These species are not at risk.

DD: There is insufficient data to rank these species.

SaR:(Species at Risk in Saskatchewan) Ranking

The Endangered Species Advisory Committee (ESAC) reviews the status assessments and advises the government on the conservation and protection of wild species at risk in Saskatchewan. They rank species on the following criteria:

EXT: These species do not exist in the wild in Saskatchewan but occur outside this province.

END: Endangered species are threatened with immediate extirpation or extinction.

THR: Threatened species are likely to become endangered if the limiting factors are not reversed.

VUL: Vulnerable species are of special concern because of low or declining numbers caused by human activities or natural events.