Describe the different categories of existing animal species.

Based on the International Union for Conservation of Nature and Natural Resources
(IUCN) existing animal species can be classified as follows:
(i) Normal species: These species are considered to be normal in their population. Such species are cattle, sal, pine and rodents.
(ii) Endangered species: These are species which are in danger of extinction. The examples are black buck, crocodile, Indian wild ass, Indian rhino, lion tailed macaque, and
sangai (brow anter deer in Manipur).
(iii) Vulnerable species: These are species whose population has decreased to such a low level that they may become endangered species in future if the present negative factors continue to operate. The examples are blue sheep, Asiatic elephant, and Gangetic dolphin.
(iv) Rare species: These are rare species but can become vulnerable or endangered species if the present trend continues. Examples are the Himalayan brown bear- wild Asiatic buffalo, desert fox and hornbill.
(v) Endemic species: These species are found in some particular areas. For example, the Andaman teal, Nicobar pigeon, Andaman wild pig, and mithun in Arunachal Pradesh.
(vi)Extinct species: These species have become extinct and are not found after searches. For example, the Asiatic cheetah and pink head duck.