Elephant is the keystone or flagship species in the forest ecosystem. In other words, the sustenance and development of the forest is hinged with the elephant. The entire system including the dependent people will have a serious setback and will be pushed to a near disaster if the population of elephants start declining. Hanuman Langur, the macaque, three deer (spotted deer, barking deer, and mouse deer), wild pig, porcupine and hare form other herbivores. Among carnivores, Panther, sloth bear, hyena, wolf, fox, jackal, mongoose(common, small, ruddy). Civets (small, palm), tree shrew and Pangolins are important.
The reptilian fauna include Bengal monitor, mud turtle, the Chameleon, Python, Cobra, Russels viper, Bamboo pit viper, Rat snake, Earth Boa etc. Mugger crocodiles (25) brought from Tikarpara were introduced in to water bodies of the sanctuary in 1992; Ambilo-3, Deras-10 and Kumarkhunti-12. Only 1 crocodile at Ambilo and 1 at Kumarkhunti have survived till date.
Avifauna can be classified in to 4 groups, viz. waterfowl & waders, raptors, ground nesting birds and song birds. Prominent ones are –
- Water fowl & waders: Dabchick, lesser Whistling teal, common Teal, Pintail, Comb duck, spot bill duck, Lapwing, River tern, Common Sandpiper, white Wagtail etc.
- Ground Nesters: Pea fowl, red Jungle fowl, red Spur fowl, grey Patridge, painted bush Quail, Stone Curlew.
- Raptors: Crested serpent eagle, Changeable hawk eagle, Osprey, Shikra, Eurasian eagle owl, Grass owl etc.
- Song birds: Rose ringed Parakeet, Indian Cuckoo, Lesser Coucal, Jungle Nightjar, Lesser pied King fisher, Blue cheeked Bee eater, Brown headed Barbet, Black headed Oriole, Indian Tree pie, Paradise Fly catcher, white rumped Shama, Black headed Munia, Eastern Skylark, small green billed Malkoha.