COSEWIC wildlife species assessment: quantitative criteria and guidelines
Table 2. Committee on the Status of Endangered Wildlife in Canada (COSEWIC) quantitative criteria and guidelines for the status assessment of wildlife species
COSEWIC’s revised criteria to guide the status assessment of wildlife species. These were in use by COSEWIC by November 2001, and are based on the revised International Union for Conservation of Nature (IUCN) Red List categories (IUCN 2001). Some minor changes to definitions were made in 2011 and 2014 to make COSEWIC criteria more consistent with IUCN criteria. An earlier version of the quantitative criteria was used by COSEWIC from October 1999 to May 2001 (Original quantitative criteria) For definitions of terms, see COSEWIC’s Glossary of Definitions and Abbreviations. This table is a short-hand reminder, for more fulsome guidance on applying these criteria see the latest IUCN Redlist guidelines.
|A1. An observed, estimated, inferred or suspected reduction in total number of mature individuals over the last 10 years or 3 generations, whichever is the longer, where the causes of the reduction are: clearly reversible and understood and ceased, based on (and specifying) any of the following1 :||Reduction of ≥ 70%||Reduction of ≥ 50%|
|(a) direct observation|
|(b) an index of abundance appropriate to the taxon|
|(c) a decline in index of area of occupancy, extent of occurrence and/or quality of habitat|
|(d) actual or potential levels of exploitation|
|(e) the effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites.|
|A2. An observed, estimated, inferred or suspected reduction in total number of mature individuals over the last 10 years or 3 generations, whichever is the 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) any of (a) to (e) under A1.||Reduction of ≥ 50%||Reduction of ≥ 30%|
|A3. A reduction in total number of mature individuals, projected or suspected to be met within the next 10 years or 3 generations, whichever is the longer (up to a maximum of 100 years), based on (and specifying) any of (b) to (e) under A1.||Reduction of ≥ 50%||Reduction of ≥ 30%|
|A4. An observed, estimated, inferred, projected or suspected reduction in total number of mature individuals over any 10 year or 3 generation period, whichever is longer (up to a maximum of 100 years in the future), where the time period must include 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) any of (a) to (e) under A1.||Reduction of ≥ 50%||Reduction of ≥ 30%|
|B1. Extent of occurrence estimated to be||< 5,000 km²||< 20,000 km²|
|B2. Index of area of occupancy estimated to be||< 500 km²||< 2,000 km²|
|and (for either B1 or B2) estimates indicating at least two of a - c:|
|a. Severely fragmented or known to exist at:||≤ 5 locations||≤ 10 locations|
|b. Continuing decline, observed, inferred or projected, in any of (i) extent of occurrence, (ii) index of area of occupancy, (iii) area, extent and/or quality of habitat, (iv) number of locations or subpopulations, (v) number of mature individuals.|
|c. Extreme fluctuations in any of (i) extent of occurrence, (ii) index of area of occupancy, (iii) number of locations or subpopulations, (iv) number of mature individuals.|
|C. Total number of mature individuals estimated to be:||< 2,500||< 10,000|
|and one of either C1 or C2:|
|C1. An estimated continuing decline in total number of mature individuals of at least:||20% within 5 years or two generations, whichever is longer, up to a maximum of 100 years in the future||10% within 10 years or three generations, whichever is longer, up to a maximum of 100 years in the future|
|C2. A continuing decline, observed, projected, or inferred, in numbers of mature individuals
and at least one of the following:
|a.(i) No subpopulation estimated to contain
|> 250 mature individuals||> 1000 mature individuals|
|a.(ii) one subpopulation has
|≥ 95% of all mature individuals||100% of all mature individuals|
|b. There are extreme fluctuations in number of mature individuals.|
|D. Total number of mature individuals very small or restricted in the form of either of the following:|
|D1. Population estimated to have||< 250 mature individuals||< 1000 mature individuals|
|D2. For threatened only: Canadian population with a very restricted index of area of occupancy (typically < 20 km²) or number of locations (typically ≤ 5) such that it is prone to the effects of human activities or stochastic events within a very short time period (1-2 generations) in an uncertain future, and is thus capable of becoming extinct, extirpated or critically* endangered in a very short period of time.||Does not apply||Index of area of occupancy typically
< 20 km²
Number of locations typically ≤ 5
|E. Quantitative analysis (population projections) showing the probability of extinction or extirpation in the wild is at least||20% within 20 years or 5 generations, whichever is longer, up to a maximum of 100 years||10% within 100 years|
*critically endangered (used only to inform application of D2)
COSEWIC procedures do not allow for a possible status of Critically Endangered; however, these criteria are useful in understanding whether or not a taxon is facing the extremely high risk of extinction in the wild required by D2. Criteria thresholds for Critically Endangered are defined in IUCN (2014). Threshold changes from Endangered are as follows:
A1, ≥ 90% population reduction.
A2, A3 or A4, ≥80% population reduction
B1, EOO < 100 km2
B2, IAO < 10 km2
- Severely fragmented or Number of locations is changed to = 1
C Criterion: Number of mature individuals < 250
C1, an estimated continuing decline in total number of mature individuals of at least 25% in 3 years or 1 generation whichever is longer
C2, a continuing decline, observed, projected, or inferred, in numbers of mature individuals and at least one of the following:
(i) No subpopulation estimated to contain more than 50 mature individuals, or
(ii) At least 90% of mature individuals in one subpopulation
D1 Criterion: Population estimated to have < 50 mature individuals
E Criterion: Quantitative analysis (population projections) showing the probability of extinction or extirpation in the wild is at least 50% within 10 years or 3 generations, whichever is longer, up to a maximum of 100 years
Those wildlife species that are particularly sensitive to human activities or natural events but are not endangered or threatened wildlife species.
Wildlife species may be classified as being of Special Concern if:
- the wildlife 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 wildlife species as Threatened; or
- the wildlife species may become Threatened if factors suspected of negatively influencing the persistence of the wildlife species are neither reversed nor managed with demonstrable effectiveness; or
- the wildlife species is near to qualifying, under any criterion, for Threatened status; or
- the wildlife species qualifies for Threatened status but there is clear indication of rescue effect from extra-limital subpopulations.
Examples of reasons why a wildlife species may qualify for "Special Concern":
- a wildlife species that is particularly susceptible to a catastrophic event (e.g., a seabird population near an oil tanker route); or
- a wildlife species with very restricted habitat or food requirements for which a 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; or
- a recovering wildlife species no longer considered to be Threatened or Endangered but not yet clearly secure.
Examples of reasons why a wildlife species may not qualify for "Special Concern":
- a wildlife species existing at low density in the absence of recognized threat (e.g., a large predatory animal defending a large home range or territory); or
- a wildlife 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 Extinct or Extirpated
A wildlife species may be assessed as extinct or extirpated from Canada if:
- there exists no remaining habitat for the wildlife species and there have been no records of the wildlife species despite recent surveys; or
- 50 years have passed since the last credible record of the wildlife species, despite surveys in the interim; or
- there is sufficient information to document that no individuals of the wildlife 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 wildlife 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 wildlife 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.
(1) Whereas (a) and (b) are methods to determine the decline in number of mature individuals and (d) and (e) are potential causes, all of (a) through (e) that indicate and/or contribute to the reduction should be stated. In addition, to use (c), there must be a reason to infer or suspect that a decline in IAO, EOO, or quality of habitat will lead to a decline in number of mature individuals that is in excess of the thresholds.