The IUCN Red List of Threatened Species

• Buffer
• Tweet

What is the IUCN?

The IUCN Red List of Threatened Species™ is the world’s most comprehensive inventory of the conservation status of plants and animals.  The Red List evaluates the extinction risk of thousands of species, using a specific set of criteria that are relevant to all species and regions of the world.  The IUCN, or International Union for the Conservation of Nature, is the oldest and largest global environmental network, with more than 1000 government and NGO member organizations. 

The goals of the IUCN Red List are to:

• Identify and document those species most in need of conservation attention if global extinction rates are to be reduced; and
• Provide a global index of the state of change of biodiversity.

The Red List is used by agencies and individuals with interests in conserving endangered species and halting the decline of biodiversity.  These include government departments, conservation-related non-governmental organizations (NGOs), natural resource planners, educational organizations and conservation biologists.  The list provides information on how threatened a particular species is and why it is threatened, but also includes species that are not currently threatened.  This enables the Red List to provide a complete picture of the overall conservation status of particular species groups and enables biodiversity trends in particular regions of the world to be assessed. 

How is the IUCN List Compiled?

The Red List is compiled by the IUCN Species Survival Commission, a network of around 7000 species experts working in every country around the world, as well as data from partner organizations including Birdlife International, Conservation International, NatureServe, and the Zoological Society of London.  The Red List is updated at least once a year and each individual species is re-evaluated at least every 10 years.

The Red List uses an objective, scientific approach to determine extinction risk.  Species are classified into one of nine categories using criteria that can be applied consistently by different people, across all species and regions of the world.  The major criteria used are rate of decline, population size, area of geographic distribution, and degree of population and distribution fragmentation.   

Categories of the Red List:

• Extinct (EX) – No 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) – Very high risk of extinction in the wild.
• Vulnerable (VU) – High risk of extinction in the wild.
• Near Threatened (NT) – Likely to move into one of the threatened categories (CR, EN, or VU) in the near future.
• Least Concern (LC) – Lowest risk. Does not qualify for a more at 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.

Species listed in Criticially Endangered, Endangered or Vulnerable categories are together described as “threatened”. For more information on each of these categories and their criteria, see IUCN Red List Categories and Criteria version 3.1.

How Many Species Are Currently on the Red List?

The 2010 IUCN Red List (version 2010.4) contains 55,926 species, of which 18,351 (33%) are known to be threatened.  There are also 8,358 species listed as Data Deficient, some of which may also be threatened. The list includes 10,027 bird species, 5,491 mammals, 2,806 reptiles, 6,296 amphibians, 8,648 fish, 9,526 invertebrates and 12,914 plant species.    

For some taxonomic groups virtually all species have been assessed, including mammals, birds, amphibians, freshwater crabs, warm-water reef building corals, conifers and cycads.  However, data is missing for many freshwater and marine species, reptiles, invertebrates and plants, and the IUCN is prioritizing a number of new Global Species Assessment Projects to address these gaps.

Using the Red List to Assess Biodiversity Trends.

The Red List is increasingly being used as a tool to monitor changes in biodiversity across the globe and to track changes in the conservation status of particular species groups.   

In 2010 data from the Red List was used to assess the conservation status of vertebrates, by tracking how approximately 25,000 species have moved between categories over time.  The study found that on average, 50 species of mammals, birds and amphibians move closer to extinction each year because of the impacts of agricultural expansion, logging, over-exploitation and invasive alien species.  However, the study found that the rate of deterioration would have been around one-fifth as much again in the absence of successful conservation measures, which have seen 64 mammal, bird and amphibian species improve in status.  Around one-fifth of the 25,000 species are classified as threatened, including 13% of all bird species and 41% of amphibians. 

Resources About The IUCN Red List of Threatened Species

Homepage of the IUCN Red List

Background information about the IUCN Red List on the IUCN website

More information about the IUCN

More on how the Red List is being used to track vertebrate extinctions

Resource by H.Miller

I am a biologist and freelance science writer based in Wellington, New Zealand. My research interests include evolution, genetics and genomics of New Zealand’s native birds and reptiles. I also write a popular science blog at www.chickenoreggblog.wordpress.com, and in my spare time enjoy biking and hiking.

Related Research For Teachers, Students, and Kids