The World Conservation Union (IUCN)

Created in 1948, the World Conservation Union (IUCN) brings together 81 States, 113 government agencies, over 850 Non-Government Organisations, and some 10,000 scientists and experts from 181 countries in a unique worldwide partnership. The Union’s mission is to influence, encourage and assist societies throughout the world to conserve the integrity and diversity of nature and to ensure that any use of natural resources is equitable and ecologically sustainable.

The IUCN Species Survival Commission (SSC)

The Species Survival Commission (SSC) is the largest of the IUCN’s six volunteer commissions with a global membership of 7,000 experts. SSC advises the IUCN and its members on a wide range of technical and scientific aspects of species conservation and is dedicated to securing a future for biodiversity. 

The taxa assessed for the IUCN Red List are the bearers of genetic diversity and the building blocks of ecosystems, and information on their conservation status and distribution provides the foundation for making informed decisions about conserving biodiversity from local to global levels.

The IUCN Red List of Threatened Species

The IUCN Red List of Threatened Species provides taxonomic, conservation status and distribution information on taxa that have been globally evaluated using the IUCN Red List Categories and Criteria. This system is designed to determine the relative risk of extinction, and the main purpose of the IUCN Red List is to catalogue and highlight those taxa that are facing a higher risk of global extinction (i.e. those listed as Critically Endangered, Endangered and Vulnerable.

The list of threatened taxa is maintained in a searchable database by the SSC Red List Programme as part of the SSC's Species Information Service (SIS).

The Red List Categories

There are nine categories in the IUCN Red List system: Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern, Data Deficient, and Not Evaluated.

Extinct (EX)
A taxon is Extinct when there is no reasonable doubt that the last individual has died. A taxon is presumed Extinct when exhaustive surveys in known and/or expected habitat at appropriate times throughout its historic range have failed to record an individual.

Extinct in the Wild (EW)
A taxon is Extinct in the Wild when it is known only to survive in cultivation, in captivity or as a naturalized population (or populations) well outside the past range. A taxon is presumed Extinct in the Wild when exhaustive surveys in known and/or expected habitat, at appropriate times throughout its historic range have failed to record an individual.

The Threatened Categories

Critically Endangered (CR) 
A taxon is Critically Endangered when it is considered to be facing an extremely high risk of extinction in the wild.

Endangered (EN)
A taxon is Endangered when it is considered to be facing a very high risk of extinction in the wild.

Vulnerable (VU)
A taxon is Vulnerable when it is considered to be facing a high risk of extinction in the wild.

Other Categories

Near Threatened (NT)
A taxon is Near Threatened when it does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for, or is likely to qualify for, a threatened category in the near future without ongoing conservation measures.

Least Concern (LC)
A taxon is Least Concern when it has been evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened. Widespread and abundant taxa are included in this category.

Data Deficient (DD)
A taxon is Data Deficient when there is inadequate information to make a direct, or indirect, assessment of its risk of extinction based on its distribution and/or population status.

Not Evaluated (NE)
A taxon is Not Evaluated when it is has not yet been evaluated against the criteria.