The following points highlight the ten main categories of animal species. The categories are: 1. Extinct (Ex) 2. Extinct in the Wild (EW) 3. Critically Endangered (CR) 4. Endangered (EN) 5. Vulnerable (VU) 6. Rare (R) 7. Conservation Dependent (CD) 8. Data Deficient (DD) 9. Low Risk (LR) 10. Not Evaluated (NE).
Category # 1. Extinct (Ex):
A species is considered to be extinct when last representative of it has died. It was estimated that India in the 17th century possessed about 13,000 species of mammals and birds, of which already more than 130 species have became extinct. Some extinct Indian species are Mountain quail, Pink headed duck, Lesser one-horned rhino, Jordon’s courser, Cheetah etc.
Among the plants India has already lost more than 20 wild plants, some with potential medicinal value. Examples of extinct species of plants-Coptis teeta, Dioscorea deltoidea, Drosera sp., Paphiopedilum drurui, Sarpagandha (Rauvolfia serpentina), Brahmakamal (Saussnrea lappa), Acorus calamus etc.
Category # 2. Extinct in the Wild (EW):
Any animal species which is known to survive in cultivation or in captivity or as a neutralized population is presumed to be extinct in the wild. Exhaustive surveys in known or expected habitat, at appropriate times (diurnal, seasonal or annual) have failed to record any individual.
Category # 3. Critically Endangered (CR):
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When an animal species faces high risk of extinction in the immediate future, such wild species are said to be critically endangered. The population of such species numbers less than 50 mature individuals. The pink pigeon (Columba mayri) of Mauritius is one such species whose number has dwindled to about 20 individuals.
Category # 4. Endangered (EN):
Animal Species that are in danger of imminent extinction due to unfavorable environmental or human factors are regarded as endangered. It is not critically endangered but are facing a very high risk of extinction in the wild in the near future and its population has been assessed to be less than 250 mature individuals.
A few examples are the black-winged Indonesian parrot (Eos cyanogenis), the tropical hawkbill turtle (Eretmochelys imbricata), the land snail (Partula rosea), the Mexican cactus (Aztekium ritteri), and the Malaysian slipper orchid (Paphiopedilum stonel). Among the Indian endangered species are Lion-tailed macaque, pygmy hog, Asiatic wild ass, brow antlered deer, hispid hare, Indian Rhinoceros, Asiatic lion, Great Indian bustard, musk deer etc.
Category # 5. Vulnerable (VU):
These are species that have sufficient number of individuals but are threatened with depletion due to some factor, and in the near future may represent the category of endangered species if unfavorable environmental conditions continue to operate. For example, Addax nasomaculatus (a member of Antelope family), crab-eating macaque, golden langur, blood pheasant, chinkara etc.
Category # 6. Rare (R):
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Rare species have small world population that are not at present endangered or vulnerable, but are at risk. Rare species are localised within restricted geographical areas or habitat or are thinly scattered over a more extensive range. Examples of rare species include-Indian egg-eating snake, Olive Ridley turtle, Indian pied hornbill, Crestless Himalayan porcupine, Golden cat etc.
Category # 7. Conservation Dependent (CD):
Animal Species that at present do not qualify as critically endangered, endangered, or vulnerable, are said to be conservation dependent. Such species are under the focus of a continuing habitat specific or species specific conservation programme.
It directly affects the species in question. In case of any discontinuity from this conservation programme will result in the species qualifying for any one of the above threatened categories. For example, South African white rhinoceros (Ceratotherium simum), has increased over the years due to strict protection and currently the number of members are 6,000 individuals.
Category # 8. Data Deficient (DD):
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A species is said to be data deficient when there is inadequate information or population status. For such species more information is required.
Category # 9. Low Risk (LR):
A species is at low risk when it does not qualify for any of the above categories.
Category # 10. Not Evaluated (NE):
When an animal species has not been assessed against any criteria, it is said to be not evaluated.