Assess species extinction risk against IUCN Red List criteria thresholds including population decline, geographic range, and population size metrics
IUCN Threat Category
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Criteria Met
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Risk Score
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Assessment Confidence
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IUCN accepts assessments from SSC members, Red List Authorities, Red List Partners, and specialists with sufficient species knowledge. All assessments must follow IUCN Red List Categories and Criteria methodology.
Generation length represents the average age of reproductive maturity in a population. It's used to scale time-based measurements in red listing and varies significantly between species types.
Extent of Occurrence is the area of the smallest polygon containing all known sites, while Area of Occupancy is the area actually occupied by the species within its range.
Under criterion B, species with fewer than 5 locations may qualify for Critically Endangered status if other conditions are met, such as continuing decline or extreme fluctuations.
A population decline of ≥50% over 10 years or 3 generations (whichever is longer) may qualify a species for Endangered status under criterion A.
IUCN Red List assessments undergo rigorous review processes and are based on standardized criteria. Assessment confidence depends on data quality and availability for each species.
Yes, species can be reassessed and moved between categories as new data becomes available or their conservation status changes due to threats or conservation actions.
Completed assessments are submitted to the IUCN Red List Unit for review and potential publication on The IUCN Red List of Threatened Species database.