Within only about 2 percent of the world's total land surface, India is known to have over 7.5% of the species of animals that the world holds. The Zoological Survey of India (ZSI), with its headquarters in Kolkata and 16 regional stations is responsible for surveying the faunal resources of India. Possessing a tremendous diversity of climate and physical conditions, India has great variety of fauna, numbering 92,037 species, of which insects alone include 61,375 species. It is estimated that about two times that number of species still remain to be discovered in India alone.
The mammals include the majestic elephant, the gaur or Indian bison - the largest of existing bovines, the great Indian rhinoceros, the gigantic wild sheep of the Himalayas, the swamp deer, the thamin spotted deer, nilgai, the four-horned antelope, the Indian antelope or black-buck - the only representatives of these genera. Among the cats, the tiger and lion are the most magnificent of all; other splendid creatures such as the clouded leopard, the snow leopard, the marbled cat, etc., are also found. Many other species of mammals are remarkable for their beauty, colouring, grace and uniqueness. Several birds, like pheasants, geese, ducks, mynahs, parakeets, pigeons, cranes, hornbills and sun birds inhabit forests and wetlands.
Rivers and lakes harbour crocodiles and gharials, the latter being the only representative of crocodilian order in the world. The salt-water crocodile is found along the eastern coast and in the Andaman and Nicobar Islands. A project for breeding crocodiles, started in 1974, has been instrumental in saving the crocodile from extinction.
The great Himalayan range has a very interesting variety of fauna that includes the wild sheep and goats, markhor, ibex, shrew and tapir. The panda and the snow leopard are found in the upper reaches of the mountains.
Depletion of vegetative cover due to expansion of agriculture, habitat destruction, over-exploitation, pollution, introduction of toxic imbalance in community structure, epidemics, floods, droughts and cyclones, contribute to the loss of flora and fauna. More than 39 species of mammals, 72 species of birds, 17 species of reptiles, three species of amphibians, two species of fish, and a large number of butterflies, moth, and beetles are considered vulnerable and endangered.
Source: India Book 2020 - A Reference Annual