The International Union for the Conservation of Nature (IUCN) Red List of Threatened Species is a global index of plant and animal species that have been evaluated depending on their conservation status.
Animals and plants are assessed on whether they are Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern or Data Deficient. Species are entered into these categories and reviewed periodically based on surviving populations and genetic diversity.
As a general guide, the categories mean:
Extinct: beyond any reasonable doubt the last individual of a species has died.
Extinct in the Wild: the species only survives in cultivation or captivity.
Critically Endangered: the species faces an extremely high risk of extinction in the wild based on any of a number of categories — population reduction rate in the past decade; extent of occurrence and fragmentation; the current overall population and estimated declining population; and a 50% or greater probability of the species becoming extinct within a decade.
Endangered: the species faces a very high risk of extinction in the wild based on similar categories to those above.
Vulnerable: the species faces a high risk of extinction in the wild based on any of similar but less extreme categories.
Near Threatened: the species does not qualify for Critically Endangered, Endangered or Vulnerable now but is close to qualifying or is likely to qualify in the near future.
Least Concern: the species is widespread and abundant.
Data Deficient: there is inadequate information to assign the species to a category.
Not Evaluated: a species has not been evaluated against any of the criteria.
For more in-depth information and to search for animals and plants on the Red List, please visit www.iucnredlist.org.
Information provided is sourced and adapted from IUCN Red List of Threatened Species, www.iucnredlist.org.