IUCN Red List

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, was founded in 1964. It is an inventory of the global conservation status and extinction risk of biological species. Countries and organizations also make Regional Red Lists, which check the risk of extinction for species within a political management unit.

The Red List aims to share science-based information about the status of species and subspecies around the world. It also draws attention to how large and important threatened biodiversity is, and it helps shape national and international policies and decisions. In addition, it gives guidance on actions that can protect biological diversity.

Several groups do most of the species assessments. These include BirdLife International, the Institute of Zoology (the research division of the Zoological Society of London), the World Conservation Monitoring Centre, and many Specialist Groups within the IUCN Species Survival Commission (SSC). Together, these organizations and groups account for nearly half of the species on the Red List.

The IUCN aims to re-evaluate the category of every species at least every ten years, and every five years if possible. This work is peer reviewed and carried out by SSC Specialist Groups, which are Red List Authorities responsible for a species, a group of species, or a specific geographic area. BirdLife International is responsible for an entire class, Aves.

As of 2023, 42,108 of the 150,388 species surveyed were considered at risk of extinction because of human activity. The main threats include overfishing, hunting, and land development.

History

At first, the Red Data Lists were made for experts and printed in a loose-leaf format that was easy to change. In 1966, conservationist Noel Simon published the first two volumes, one on mammals and one on birds. Later volumes covered reptiles and amphibians, created by René E. Honegger in 1968, and plants (angiosperms only), compiled by Ronald Melville in 1970. The last loose-leaf volume, on freshwater fishes, was published in 1979 by Robert Rush Miller. In 1969, The Red Book: Wildlife in Danger was the first attempt to reach a general audience. It focused mostly on mammals and birds, with smaller sections on reptiles, amphibians, fishes, and plants.

The 2006 Red List, released on 4 May 2006, evaluated 40,168 species as a whole, plus 2,160 additional subspecies, varieties, aquatic stocks, and subpopulations. On 12 September 2007, the World Conservation Union (IUCN) released the 2007 list. It raised the western lowland gorilla and the Cross River gorilla from endangered to critically endangered, the last category before extinct in the wild, because of Ebola virus, poaching, and other factors. Russ Mittermeier, chief of Swiss-based IUCN's Primate Specialist Group, said 16,306 species were endangered with extinction. The list also placed the Sumatran orangutan in the Critically Endangered category and the Bornean orangutan in the Endangered category. In 2008, the Blue List was released in Barcelona. It confirmed an extinction crisis, showing that at least 1,141 of the 5,487 mammals on Earth were threatened, and 836 were listed as Data Deficient. The 2012 Red List, released at the Rio+20 Earth Summit, added nearly 2,000 species and found that 19,817 of the 63,837 species assessed were threatened with extinction.

Categories

The IUCN Red List sorts species into nine groups. Scientists look at things like how fast a species is declining, how many members it has, how large an area it lives in, and how broken up its homes are. Even when good information is missing, they may use suspected or possible future threats, as long as these can reasonably be supported. Extinct means there is no reasonable doubt that the species is gone. Extinct in the wild means it survives only in captivity, in cultivation, or outside its native range, based on thorough searching. Critically endangered species are in an extremely serious state. Endangered species have a very high risk of extinction in the wild. Vulnerable species are at high risk of human-caused extinction without further human help. Near Threatened species are close to being endangered in the near future, while Least Concern species are widespread and plentiful. Data Deficient means there is not enough information to judge the risk, and Not Evaluated means the species has not yet been assessed. "Threatened" is the name for Critically Endangered, Endangered, and Vulnerable species together.

The older 1994 list had one "Lower Risk" group with three parts: Conservation Dependent, Near Threatened, and Least Concern. In the 2001 system, Near Threatened and Least Concern became their own categories, and Conservation Dependent was removed and merged into Near Threatened. BirdLife International, the Red List authority for birds, uses a "possibly extinct" (PE) tag. It recommended that PE become an official tag for Critically Endangered species, and this has now been adopted, along with a "Possibly Extinct in the Wild" tag for species with populations surviving in captivity but likely to be extinct in the wild.

Versions

The Red List has had a number of versions since 1991. They began with Version 1.0 and reached Version 3.1 in 2001.

Since 2001, all new IUCN assessments have used version 3.1 of the categories and criteria, which are the rules used to sort species by their risk of extinction.

Criticism

In 1997, the IUCN Red List was criticized for being secretive, or at least for not clearly recording where its information came from. The IUCN responded by working to improve its documentation and data quality, and by including peer reviews of species on the list. The list also accepts petitions against its classifications, based on documentation or criteria.

In 2002, an article in Trends in Ecology & Evolution suggested that the Red List and similar works can be misused by governments and other groups, who may draw unsuitable conclusions about the state of the environment or use them to affect exploitation of natural resources. In 2016, a research article in Science Advances claims there are serious inconsistencies in how the IUCN classifies species. The researchers say the process is "out-dated, and leaves room for improvement," and they stress the value of easy-to-use location data, such as satellite and aerial images. They believe combining this kind of data could greatly increase the number of species that need to be moved to a higher risk category.