What are the classification criteria of a threatened species?

The International Union for Conservation of Nature (IUCN) is the international authority on the conservation status of species. IUCN Red List categories and criteria are used to evaluate the extinction risk of thousands of species and subspecies. The IUCN Red List is the world’s most comprehensive information source on the global extinction risk status of animal, plant and fungus species. It is a critical indicator of the health of the world’s biodiversity.

The IUCN Red List categories are:

* Extinct (EX) - No known individuals of the species remain alive.

* Extinct in the Wild (EW) - The species survives only in captivity, with no free-ranging population left.

* Critically Endangered (CR) - The species is facing an extremely high risk of extinction in the wild.

* Endangered (EN) - The species is facing a very high risk of extinction in the wild.

* Vulnerable (VU) - The species is facing a high risk of extinction in the wild.

* Near Threatened (NT) - The species is close to meeting the criteria for a threatened category, but is not there yet.

* Least Concern (LC) - The species is widespread and abundant, with no immediate threat to its survival.

* Data Deficient (DD) - There is not enough information available to assess the status of the species.

* Not Evaluated (NE) - The species has not yet been assessed by the IUCN.

The IUCN Red List criteria are a set of objective, science-based criteria that are used to evaluate the extinction risk of species. The criteria are based on factors such as population size, range size, population decline, and fragmentation.

The IUCN Red List is an important tool for conservation planning and decision-making. It helps to identify species that are most at risk of extinction, and it provides information that can be used to develop conservation strategies for those species.