The park supports exceptionally diverse wildlife populations. It harbors a total of 53 species of mammals, ca400 species of avifauna, 25 species of reptiles and amphibians and 121 species of fishes. Major findings of the bio-diversity inventory are presented separately in Basnet (1995). Checklists of mammals, birds, amphibians/reptiles and flora are presented in Annexes.

Several wildlife species found in the park are listed as protected species according to wildlife and conservation act 1973. The protected mammals in the park include tiger Panther tigris tigris, one - horned rhinocers Rhinoceros unicornis, Asiatic wild elephant Elephas maximus, swamp deer cervus duvauceli duvauceli, Gangetic dolphin Platanista gangetica, striped hyaena Hyaena hyaena, four horned antelope Tetraceros quardricornis and Chinese pangolin Manis pentadactyla. Similarly, the protected birds recorded in the park are Giant Hornbill Buceros bicornis, Black Stork Ciconia nigra, Sarus Crane Grus antigone, Bengal Flerican Eupodtis bengalensis, and Lesser Florican Sypheotides indica. Gharial gangeticus and phyton molurus are reptiles in the similar category. In addition, large population of spotted deer, hogs deer, barking deer and wild boar together with avian - herpeto fauna and invertebrates enrich the biological diversity of the park.

As a part of species conservation, 58 greater one-horned rhinoceros were translocated (1986-13,1991-25,1999-4and 2000-16) from Chitwan National Park and released in Karnali and Babai river basins (Jnawali2000). Current population of rhinoceros including 16 individuals released in 2000 is estimated at 73 .Of them, 41 are residing in Babai valley and 32 in Geruwa floodplain.

Similarly, tigers occupy floodplainsof geruwa, Orai and Babai as well as sal forest between Geruma River and foothill of Siwalik rang of East West Highway. The tiger population in the park is estimated at about ca 50 breeding adults.

Elephant population in the park consists of both migratory and resident individuals. Elephant population until 1992 was estimated at only 2 males roaming in the southwestern section of the park. Size of elephant population was increased as 23 individuals migrated during 1993/94 dry season. Later in 1999 the number of wild elephant in Bardia was found to be above 40 individuals. The only wild population of black buck (ca 45 individuals) survives at Khairapur (out sides the park), ca 40 km southeast from the park Headquarters. Himalayan black bear (Selenarctos thibetanus) was recorded for the first time in Babai valley during dry season, 2000 .Sloth bear (Ursus mekursus) are found in some areas and a small population of bluebull (Boselaphus tragocamelus) is found in southern part of the park.