The World Conservation Union (IUCN) publishes a list every year — called the Redlist — which includes all species considered Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Conservation Dependent, Near Threatened, Least Concern or Data Deficient. Species are entered into these categories and reviewed annually based on surviving populations and genetic diversity.

As a general guide, the categories mean:

• Extinct: beyond any reasonable doubt that the last individual has died.

• Extinct in the Wild: it is known only to survive in cultivation or captivity.

• Critically Endangered: considered to be facing an extremely high risk of extinction in the wild based on ANY of five categories — population reduction rate in the past decade; extent of occurrence and fragmentation; the current overall population and estimated declining population; and quantitative analysis rresults indicate the extinction probability within a decade is at least 50%.

• Endangered: considered to be facing a very high risk of extinction in the wild based on similar categories.

• Vulnerable: considered to be facing a high risk of extinction in the wild based on ANY of similar but less extreme categories.

• Near Threatened: 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: widespread and abundant species are included in this criteria.

• Data Deficient species means there is inadequate information to make a direct or indirect assessment of a species' risk of extinction.Species may be well studied and their environment well known but appropriate data on populations is lacking.