Critically Endangered
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Critically Endangered

A critically endangered (CR) species is one that has been categorized by the International Union for Conservation of Nature (IUCN) as facing an extremely high risk of extinction in the wild.[1]

As of 2014, there are 2464 animal and 2104 plant species with this assessment, compared with 1998 levels of 854 and 909, respectively.[2]

As the IUCN Red List does not consider a species extinct until extensive, targeted surveys have been conducted, species that are possibly extinct are still listed as critically endangered. IUCN maintains a list[3] of "possibly extinct" CR(PE) and "possibly extinct in the wild" CR(PEW) species, modelled on categories used by BirdLife International to categorize these taxa.

International Union for Conservation of Nature definition

To be defined as critically endangered in the Red List, a species must meet any of the following criteria (A-E) ("3G/10Y" signifies three generations or ten years--whichever is longer--over a maximum of 100 years; "MI" signifies Mature Individuals):[4]

A: Population size reduction
1. If the reasons for population reduction no longer occur and can be reversed, the population needs to have been reduced by at least 90%
2. 3. and 4. If not, then the population needs to have been reduced by at least 80%
B: Occurring over less than 100 km² OR the area of occupancy is less than 10 km²
1. Severe habitat fragmentation or existing at just one location
2. Decline in extent of occurrence, area of occupancy, area/extent/quality of habitat, number of locations/subpopulations, or amount of MI.
3. Extreme fluctuations in extent of occurrence, area of occupancy, number of locations/subpopulations, or amount of MI.
C: Declining population of less than 250 MI and either:
1. A decline of 25% over 3G/10Y;
2. Extreme fluctuations, or over 90% of MI in a single subpopulation, or no more than 50 MI in any one subpopulation.
D: Numbers less than 50 MI.
E: At least 50% chance of going Extinct in the Wild over 3G/10Y.

See also

Notes

  1. ^ "IUCN RED LIST CATEGORIES AND CRITERIA" (PDF). 2000-02-09. Retrieved .
  2. ^ IUCN (2014). "Table 2: Changes in numbers of species in the threatened categories (CR, EN, VU) from 1996 to 2014 (IUCN Red List version 2014.2) for the major taxonomic groups on the Red List" (PDF). Retrieved .
  3. ^ "Summary Statistics". www.iucnredlist.org. Retrieved .
  4. ^ IUCN (February 2014). "Guidelines for Using the IUCN Red List Categories and Criteria" (PDF). Retrieved 2018.

References

External links


  This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.

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