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NORTHERN SPOTTED OWL (Strix occidentalis caurina)

Appendix 4

COSEWIC Criteria for Endangered and Threatened Species

COSEWIC Organization and Procedures Manual

Table 2: COSEWIC Criteria for Endangered and Threatened Species
These are essentially IUCN Red List criteria (IUCN 1994) that were reviewed and evaluated by COSEWIC (COSEWIC 1999). See IUCN Red List Categories (IUCN 1994) for definitions and interpretation guidelines.
A. Declining Total Population
Population decline rate of at least:50% in 10 years or 3 generations
20% in 10 years or 3 generations

using either

(1) population reduction observed, estimated, inferred‚ or suspected in the past

or    (2) population decline projected or suspected in the future.

based on

a) direct observation

b) an index of abundance appropriate for the taxon

c) a decline in area of occupancy, extent of occurrence and/or quality of habitat

d) actual or potential levels of exploitation

e) the effects of introduced taxa, hybridisation, pathogens, pollutants, competitors or parasites

B. Small Distribution and Decline or Fluctuation
Either extent of occurrence 
or area of occupancy
and any 2 of the following 3:
<5,000 km2
<500 km2   
<20‚000 km2
<2‚000 km2
1) either severely fragmented: (isolated populations with a reduced probability of recolonization, once extinct)
or known to exist at # locations   ≤5 ≤10

(2) continuing decline in any of the following:

a) extent of occurrence

b) area of occupancy

c) area, extent and/or quality of habitat

d) number of locations or populations

e) number of mature individuals

(3) fluctuating in any of the following:

a) extent of occurrence

b) area of occupancy

c) number of locations or populations

d) number of mature individuals

any rate    






>1 order/mag    

any rate






>1 order/mag

C. Small Total Population Size and Decline
Number of mature individuals and 1 of the following 2:<2‚500     <10,000
(1) rapid decline rate of at least  20% in 5 years or  2 generations 10% in 10 years or 3 generations

(2) continuing decline and either

(a) fragmentation  

or  (b) all individuals in a single population

any rate  

all populations <250 

any rate

all populations <1‚000

D. Very Small or Restricted


(1) # of mature individuals
(2) population is susceptible    



(not applicable) 



area of occupancy <100 km2or # of locations ≤5

E. Quantitative Analysis
Indicating the probability of extinction in the wild to be at least: 20% in 20 years or   5 generations10% in 100 years

Special Concern:

Species which are particularly sensitive to human activities or natural events but are not endangered or threatened species.

Examples of reasons why a species may qualify for “Special Concern”:

  • A species that is particularly susceptible to a catastrophic event (e.g., a large seabird population near oil tanker route)
  • A conservation-dependent species that would likely become at risk if not for active protection and management (e.g., a fish or mammal species protected from over-harvest)
  • A recovering species, no longer qualifying for risk categories but not yet clearly secure, or subject to resumption of threat in future

Examples of reasons why a species may not qualify for “Special Concern”:

  • Rarity alone in the absence of recognized threat
  • Threat with little possibility of serious harm (e.g., large, fecund population subject to harvest)