There are 55 species of mammals, 361 species of birds, 62 species of reptiles, 21 species of amphibians and many species of insects and micro fauna. It holds the highest tiger population in Odisha, and harbours the only population of melanistic tigers in the world. Other carnivores found here are leopard, leopard cat, fishing cat, jungle cat and wolf. The active management of mugger has revived its population on the banks of the rivers Khairi and Deo.
Similipal Tiger Reserve is also home to the largest population of elephants in Odisha. The major ungulate species found here are Sambar, Chital, Barking deer, Gaur and Mouse deer.