Table 2: COSEWIC Quantitative Criteria and Guidelines for the Status Assessment of Species
COSEWIC's revised criteria to guide the status assessment of species. These were in use by COSEWIC by November 2001, and are based on the revised IUCN Red List categories (IUCN 2001). An earlier version of the quantitative criteria was used by COSEWIC from October 1999 to May 2001 (these original criteria and the associated definitions can be viewed here). Definitions of terms are provided in Table 6.
A. Declining Total Population
Reduction in population size based on any of the following 4 options and specifying a-e as appropriate:
(A1) population size reduction that is observed, estimated, inferred, or suspected in the past 10 years or 3 generations, whichever is longer, where the causes of the reduction are clearly reversible AND understood AND ceased, based on (and specifying) one or more of a-e below.
|> 70 %||> 50 %|
|(A2) population size reduction that is observed, estimated, inferred or suspected over the last 10 years or 3 generations, whichever is longer, where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible, based on (and specifying) one or more of of a-e under A1.||> 50 %||> 30 %|
|(A3) population size reduction that is projected or suspected to be met within in the next 10 years or 3 generations, whichever is longer (up to a maximum of 100 years), based on (and specifying) one or more of b-e under A1.||> 50 %||> 30 %|
|(A4) population size reduction that is observed, estimated, inferred, projected or suspected over any 10 year or 3 generation period, whichever is longer (up to a maximum of 100 years), where the time period includes both the past and the future, AND where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible, based on (and specifying) one or more of a-e under A1.||> 50 %||> 30 %|
B. Small Distribution, and Decline or Fluctuation
|(B1) Extent of occurrence; or||< 5,000 km2||< 20,000 km2|
|(B2) Area of occupancy.|
For either of the above, specify at least two of a-c:
|< 500 km2||< 2,000 km2|
|(a) either severely fragmented or known to exist at # locations||< 5||< 10|
(b) continuing decline observed, inferred or projected in one or more of the following:
(c) extreme fluctuations in one or more of the following:
|> 1 order of magnitude||> 1 order of magnitude|
C. Small Total Population Size and Decline
|Number of mature individuals and 1 of the following 2:||< 2,500||< 10,000|
|(C1) an estimated continuing decline rate of at least: or||20% in 5 years or 2 generations (up to a maximum of 100 years in the future)||10% in 10 years or 3 generations (up to a maximum of 100 years in the future)|
|(C2) continuing decline, observed, projected, or inferred, in numbers of mature individuals and at least one of the following (a-b):|
|(a) fragmentation -- population structure in the form of one of the following:||(i) no population estimated to contain >250 mature individuals|
(ii) at least 95 % of mature individuals in one population
|(i) no population estimated to contain >1,000 mature individuals|
(ii) all mature individuals are in one population
|(b) extreme fluctuations in the number of mature individuals|
D. Very Small Population or Restricted Distribution
|(D1) Number of mature individuals; or||< 250||< 1,000|
|(D2) Applies only to threatened: Population with a very restricted area of occupancy (area of occupancy typically < 20 km2) or number of locations (typically 5 or fewer) such that it is prone to the effects of human activities or stochastic events within a very short time period in an uncertain future, and thus is capable of becoming highly endangered or even extinct in a very short time period.|
E. Quantitative Analysis
|Indicating the probability of extinction in the wild to be at least:||20% in 20 years or 5 generations, whichever is longer (up to a maximum of 100 years)||10% in 100 years|
those species that are particularly sensitive to human activities or natural events but are not endangered or threatened species.
Species may be classified as being of Special Concern if:
- the species has declined to a level of abundance at which its persistence is increasingly threatened by genetic, demographic or environmental stochasticity, but the decline is not sufficient to qualify the species as Threatened; or
- the species is likely to become Threatened if factors suspected of negatively influencing the persistence of the species are neither reversed nor managed with demonstrable effectiveness; or
- the species is near to qualifying, under any criterion, for Threatened status; or
- the species qualifies for Threatened status but there is clear indication of rescue effect from extra-limital populations.
Examples of reasons why a species may qualify for "Special Concern":
- A species that is particularly susceptible to a catastrophic event (e.g., a seabird population near an oil tanker route)
- A species with very restricted habitat or food requirements for which a potential threat to that habitat or food supply has been identified (e.g., a bird that forages primarily in old-growth forest, a plant that grows primarily on undisturbed sand dunes, a fish that spawns primarily in estuaries, a snake that feeds primarily on a crayfish whose habitat is threatened by siltation)
- A recovering species no longer considered to be Threatened or Endangered but not yet clearly secure
Examples of reasons why a species may not qualify for "Special Concern":
- A species existing at low density in the absence of recognized threat (e.g., a large predatory animal defending a large home range or territory)
- A species existing at low density that does not qualify for Threatened status for which there is a clear indication of rescue effect
Guidelines for use of Extirpated
A species may be assessed as extinct or extirpated from Canada if:
- there exists no remaining habitat for the species and there have been no records of the species despite recent surveys, or
- 50 years have passed since the last credible record of the species, despite surveys in the interim, or
- there is sufficient information to document that no individuals of the species remain alive.
Guidelines for use of Data Deficient
Data Deficient should be used for cases where the status report has fully investigated all best available information yet that information is insufficient to: a) satisfy any criteria or assign any status, or b) resolve the species' eligibility for assessment.
- Records of occurrence are too infrequent or too widespread to make any conclusions about extent of occurrence, population size, threats, or trends.
- Surveys to verify occurrences, when undertaken, have not been sufficiently intensive or extensive or have not been conducted at the appropriate time of the year or under suitable conditions to ensure the reliability of the conclusions drawn from the data gathered.
- The species' occurrence in Canada cannot be confirmed or denied with assurance.
Data Deficient should not be used if: a) the choice between two status designations is difficult to resolve by COSEWIC, or b) the status report is inadequate and has not fully investigated all best available information (in which case the report should be rejected), or c) the information available is minimally sufficient to assign status but inadequate for recovery planning or other such use.
- Date Modified: