The fauna of Arunachal Pradesh is equally rich with as many as 25 species of mammals included in Schedule – I of the Wildlife (Protection) Act, 1972.
    The large herbivours of the foot-hills and adjoining plains are the elephant (Elephas maximus), gaur (Bos gaurus) and the wild buffalo (Bubalus bufalis). The fauna of Arunachal Pradesh is equally rich with as many as 25 species of mammals included in Schedule – I of the Wildlife (Protection) Act, 1972.

Arunachal Pradesh is perhaps the only State which has four major cats, i.e. tiger (Panthera tigris), leopard (Panthera pardus), clouded leopard (Neofelis nebulosa) and snow leopard (Panthera uncia). Lesser cats like the golden cat, leopard cat and the marbled cat are also found here.

Seven species of primates i.e. hoolock gibbon, slow loris, Assamese macaque, rhesus macaque, pig-tailed macaque, stump-tailed macaque, and capped langur also occur in the forests of the State. This is the only state where all the 3 goat antelopes occurring in India, i.e. serow, goral and takin are found. The highly endangered hispid hare (caprolagus hispidus) is also found in low grassy areas of the State.

Among the smaller mammals several Rodents (squirrel, porcupine and rats), Civets, mongoose, linsang, shrew and bat species are also to be found. On higher elevations, animals like goral, Himalayan black bear, red panda, are met with in various parts of the State. Over 500 bird species inhabit Arunachal Pradesh including some endangered and endemic ones like, white winged wood duck, Sclater’s Monal, Temmincks Tragopan, black necked crane, Mishmi wren and Bengal florican. The 'Mithun' (Bos Frontails) exist both in wild and semi-domesticated form. This animal has religious significance and intimate relation with socio-cultural life of the people. Traditionally, the mithun is a unit of wealth and is allowed to move freely in jungle till it is either used for food on festive occasions and marriage feasts, or for barter.

Arunachal Pradesh is also the happy home of the great Indian Hornbills-the set extraordinary bird with an inordinately large beak which is also the State bird.The white winged wood duck, a rare endangered species, has been sheltered in Namdapha National Park. Namdapha sanctuary was upgraded to the status of National park in 1983.

This is the richest State for pheasants, with some ten species occupying different altitudes from the plains to the snowy heights. The State also abounds in a variety of reptiles, amphibians, pisces and innumerable species of butterflies, moths, beetles and other insects.

         There are two national parks and nine wild life sanctuaries in the State managed by the forest department.