Environment

IUCN Red List

Also: Red List of Threatened Species, IUCN, Red Data Book

Definition

The world's most comprehensive inventory of the global extinction risk of species, maintained by the International Union for Conservation of Nature, which places species into categories from Least Concern to Extinct using standard scientific criteria.

Summary card: IUCN Red List. IUCN founded 1948; headquarters at Gland, Switzerland. Red List started in 1964. Nine categories, from Not Evaluated to Extinct. "Threatened" = Critically Endangered, Endangered, Vulnerable. Over 160,000 species assessed — Summary card © UPSCPrep.in

Background and evolution

The International Union for Conservation of Nature, founded in 1948 at Fontainebleau in France, is unusual: its members include both governments and non-governmental organisations, and it draws on thousands of volunteer scientists organised in commissions. Its Species Survival Commission began publishing lists of threatened species in 1964, initially as "Red Data Books" printed on red pages to signal danger.

The early lists relied heavily on expert opinion. In the 1990s the IUCN adopted quantitative criteria, such as the rate of population decline, the size of geographic range, the number of mature individuals and the probability of extinction, so that assessments could be repeated and compared. The current categories and criteria (version 3.1) were adopted in 2001. The list is updated several times a year.

Old painting of a Great Indian Bustard — A Great Indian Bustard painted by Robert Mabon in the early 19th century. The bird is now Critically Endangered on the IUCN Red List. Photo: Robert Mabon (Yale Center for British Art), CC0, via Wikimedia Commons.

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Last reviewed: 23 October 2026 · Original UPSCPrep.in content.