Sikkim has a number of rare animal species. Poor conservation practices have resulted in decimation of their populations. Of the 144 mammals known to exist in the state, 39 are regarded as endangered or rare. These include the red panda, east Himalayan tahr, musk deer, snow leopard, jungle cat, marbled cat, golden cat, leopard cat, clouded leopard, tree shrew, Tibetan wolf, red fox, Indian wild dog, hog badger, Tibetan sheep, bharal, serow and goral. Many of these rare-endangered species have been sighted in parts of Kangchendzonga National Park.

Sikkim has over 550 bird species and sub-species, ranging from the majestic bearded vulture, which has a wingspan of over 10 ft, to the tiny Olive ground warbler. Many of these species are endemic to the Eastern Himalayas and are found only in this region.Apart from comparatively common birds like dove, parrots, cuckoo, owls, kingfisher, ducks, goshawk, hawks and woodpecker, Sikkim has a variety of less common birds including Pekin robins, fly-catcher warblers, sandpipers and hornbills. Rare species of pheasants and game birds like partridge and woodcock are also found in the state. Of these, at least 11 species are found only in north Sikkim.