Fig. 11.2.

The International Union for Conservation of Nature (IUCN) has devised a classification scheme that evaluates species against objective criteria, such as population size and distribution and their trends, thus allowing them to be placed into one of the categories shown here. Species for which there is adequate information can be evaluated as at greater or lesser risk of extinction. At highest risk are species that can be presumed Extinct or are thought to be Extinct in the Wild. At lowest risk are species evaluated as being of Least Concern. Species that are not well enough known to assign to a risk category are considered Data Deficient. Species in all of these categories can be found on the IUCN Red List (http://www.iucnredlist.org/). Other species may be known but have not yet been evaluated, for example, because they have been recently described. Source: Reproduced with permission from IUCN (2012).