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The IUCN Red List of Threatened Species by the International Union for Conservation of Nature is the best known worldwide conservation status listing and ranking system. . Species are classified by the IUCN Red List into nine groups set through criteria such as rate of decline, population size, area of geographic distribution, and degree of population and distribution fragmenta
A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of critical depensation, a mathematical measure of biomass related to population growth rate. This quantitative metric is one ...
Extinct in the Wild (EW): captive individuals survive, and/or the species has been reintroduced outside its former natural range, but the species otherwise matches the criteria for "Extinct", such that no free-living, natural population is believed to exist. "Extirpated" is a term used for localized extinctions of extant species; it always ...
Endangered species are addressed through Canada's Species at Risk Act. A species is deemed threatened or endangered when it is on the verge of extinction or extirpation. Once a species is deemed threatened or endangered, the Act requires that a recovery plan to be developed that indicates how to stop or reverse the species' population decline. [33]
The Red List of 2012 was released 19 July 2012 at Rio+20 Earth Summit; [17] nearly 2,000 species were added, [18] with 4 species to the extinct list, 2 to the rediscovered list. [19] The IUCN assessed a total of 63,837 species which revealed 19,817 are threatened with extinction.
The species recovery score is a 0%–100% scale, with 0% being the species is extinct or extinct in the wild and 100% being fully recovered. [40] In addition, the Green Status also classifies previous and future conservation impacts with the Green Scores of Conservation Dependency, Conservation Gain, Conservation Legacy, and Recovery Potential.
The term endangered has also been used in other contexts with similar meaning but slightly different definitions. A proposal of classification of Endangered Ecosystems of the United States considered the category endangered for ecosystems evidencing 85–98% decline. [20]
Those species that are extant, yet are threatened with extinction, are referred to as threatened or endangered species. The dodo of Mauritius, shown here in a 1626 illustration by Roelant Savery, is an often-cited example of modern extinction. [25] Currently, an important aspect of extinction is human attempts to preserve critically endangered ...