The International Union for Conservation and Nature (IUCN) is an international organisation that was set up in 1948. Each year it assess the threat to endangered species by counting or estimating the number of as many species as possible. This is called the Red List. The list places animals in various degrees of endangerment, according to the numbers still surviving and the potential threats to their survival.
IUCN provide the most comprehensive global accounting of endangered species, classifying vulnerable species on a spectrum that ranges from “near threatened” to “extinct,” with the “endangered” classification sitting in the middle. IUCN considers a wide range of criteria to determine whether a species qualifies as endangered, including a shrinking population, issues that prevent reproduction and vulnerability of the species’ habitat.
When discussing the IUCN Red List, the official term “threatened” is a grouping of three categories: critically endangered, endangered, and vulnerable.
• Extinct (EX) – No known individuals remaining
• Extinct in the wild (EW) – Known only to survive in captivity, or as a naturalized population outside its historic range
• Critically endangered (CR) – Extremely high risk of extinction in the wild
• Endangered (EN) – High risk of extinction in the wild
• Vulnerable (VU) – High risk of endangerment in the wild
• Near threatened (NT) – Likely to become endangered in the near future
• Least concern (LC) – Lowest risk; does not qualify for a higher risk category. Widespread and abundant taxa are included in this category
• Data deficient (DD) – Not enough data to make an assessment of its risk of extinction
• Not evaluated (NE) – Has not yet been evaluated against the criteria