IUCN Red List Categories

The IUCN Red List of Threatened Species is the world's main list showing how close each species is to extinction. It is managed by the International Union for Conservation of Nature (IUCN). Experts study a species and place it in one of nine categories, ranging from "Least Concern" (safe for now) to "Extinct" (gone forever). It is often called the "Barometer of Life", because it shows the health of the world's species.

Why does it exist?

Governments and conservation groups have limited money and time. They need to know which species are in the most danger so they can act first where it matters most. The Red List gives a common, scientific scale used everywhere in the world. It guides laws, trade rules, funding and the choice of protected areas.

Where did it come from?

• 1948: IUCN was founded on 5 October 1948 in Fontainebleau, France. Its headquarters is in Gland, Switzerland. It is unusual because its members include both governments and non-government organisations.
• 1964: IUCN started the Red List. Early versions were printed as Red Data Books.
• 1994: IUCN adopted the first set of clear, number-based criteria for placing species into categories.
• 2001: The current version (Categories and Criteria, Version 3.1) was adopted.
• India became a State Member of IUCN in 1969, through the Ministry of Environment.

What are the nine categories?

From most to least at risk:

1. Extinct (EX): No reasonable doubt that the last individual has died.
2. Extinct in the Wild (EW): Survives only in zoos, captivity or outside its natural range.
3. Critically Endangered (CR): Extremely high risk of extinction in the wild.
4. Endangered (EN): Very high risk of extinction in the wild.
5. Vulnerable (VU): High risk of extinction in the wild.
6. Near Threatened (NT): Close to qualifying as threatened, or likely to soon.
7. Least Concern (LC): Widespread and common; low risk for now.
8. Data Deficient (DD): Not enough information to judge its risk.
9. Not Evaluated (NE): Not yet assessed.

Only CR, EN and VU together are called "threatened" species.

How is a species placed in a category?

Experts check the species against five criteria (A to E). If it meets any one of them, it goes into the highest category it qualifies for.

• A: Population falling fast. For example, a fall of 80% or more over 10 years or three generations can mean CR; 50% or more, EN; 30% or more, VU. (Higher thresholds of 90%, 70% and 50% apply when the causes are known to have stopped.)
• B: Small and shrinking range. The area where it lives is tiny, broken into pieces, or getting smaller. For example, an extent of occurrence under 100 sq km can mean CR.
• C: Small population that is also falling. Fewer than 250 mature individuals (CR), 2,500 (EN) or 10,000 (VU), along with a continuing decline.
• D: Very small population. Fewer than 50 mature individuals (CR), 250 (EN) or 1,000 (VU).
• E: Computer analysis of extinction risk. A chance of extinction of at least 50% in 10 years or three generations (CR), 20% in 20 years or five generations (EN), or 10% in 100 years (VU).

A mature individual means an adult that can breed. Babies and very old animals that cannot breed are not counted.

Key facts and numbers

As of 2025, the Red List has assessed more than 1.6 lakh species, and more than 47,000 of them are threatened with extinction. Assessments are done by expert groups and partner bodies, and the list is updated a few times each year. IUCN also publishes a Red List Index, which shows whether species, on average, are moving towards or away from extinction over time.

In 2021, IUCN added a Green Status of Species, which measures how far a species has recovered, not just how close it is to extinction.

India and the Red List

Many Indian species are well-known Red List examples:

• Critically Endangered: Great Indian Bustard, Kashmir stag (Hangul), Malabar large-spotted civet, Namdapha flying squirrel, Jenkins's shrew, gharial
• Endangered: Bengal tiger, Asian elephant, Ganga river dolphin, red panda
• Vulnerable: Indian one-horned rhinoceros, snow leopard, sloth bear, African cheetah (the type brought to India under Project Cheetah)

Indian law uses a different list. The Wildlife (Protection) Act, 1972 places species in Schedules. Schedule I gives the highest protection. After the 2022 amendment, the Act has four schedules. A species' Red List status and its Schedule do not always match.

Commonly confused concepts

• Red List vs Red Data Book: The Red Data Book was the older printed form of the list. Today the Red List is an online database. India's Botanical Survey and Zoological Survey also publish their own Red Data Books on Indian species.
• IUCN Red List vs CITES Appendices: The Red List shows extinction risk and has no legal force. CITES (Convention on International Trade in Endangered Species, 1973) is a treaty that controls international trade. Appendix I bans commercial trade; Appendix II allows controlled trade; Appendix III lists species protected by one country that asks others for help.
• IUCN Red List vs Wildlife (Protection) Act Schedules: The Red List is a global, scientific assessment. The Schedules are Indian law, with punishments for hunting or trade.
• Extinct vs Extinct in the Wild: "Extinct" means no individual is left anywhere. "Extinct in the Wild" means some survive only in captivity.
• Endangered (IUCN category) vs "endangered" (common word): In everyday speech, "endangered" means any species at risk. In the Red List, "Endangered" is one specific category, between Critically Endangered and Vulnerable.

Issues, criticism and the way forward

• Gaps in coverage: Mammals, birds and amphibians are well assessed, but most insects, fungi and plants are not. The assessed species are a small share of all life on Earth.
• Old assessments: Many species have not been re-checked for over ten years, so their status may be out of date.
• Data Deficient species: Thousands of species are listed as Data Deficient. Some of them may in fact be threatened.
• Bias towards rich countries: Experts and funding are concentrated in richer countries, while the most species-rich regions are in the tropics.
• Way forward: IUCN aims to assess more plants, fungi and invertebrates, re-assess species regularly, train experts in developing countries, and use citizen science (data collected by ordinary people) to fill gaps.

Concepts to Know

• Extinction: When a species dies out completely and no individual is left.
• Generation: The average age of parents in a population. For long-lived animals like elephants, three generations can be several decades.
• Extent of occurrence: The total area within the outer boundary of all places where a species is found.
• Mature individual: An adult animal or plant that is able to reproduce.
• CITES: An international treaty (1973) that controls trade in wild animals and plants across borders. India is a party.
• Citizen science: Scientific data collected by ordinary people, such as birdwatchers recording sightings on mobile apps.