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Critically endangered species

Critically Endangered is the highest risk category assigned by the IUCN Red List for wild species. Critically Endangered species are those that are facing a very high risk of extinction in the wild.[1] There are currently 2129 animals and 1821 plants with this assessment, compared with 1998 levels of 854 and 909, respectively.[2]

As the Red List does not consider a species extinct until extensive, targeted surveys have been conducted, species which are possibly extinct are still listed as 'Critically Endangered'. A new ideal category for 'Possibly Extinct' has been suggested by BirdLife International to categorize these taxa.

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IUCN 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):[3]

A: Occurring over less than 100 km² and two of:
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.
B: As above, but less than 10 km² (used to show differing levels of severity).
C: Declining population of less than 250 MI and either:
1. A decline of 25% over 1G/3Y;
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.

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