Bundala National Park is an internationally important wintering ground for migratory waterbirds in Sri Lanka. Bundala harbors 197 species of birds, the highlight being the greater flamingo, which migrates in large flocks. Bundala was designated a wildlife sanctuary in 1969 and redesigned to a national park on 4 January 1993.

The Bundala National Park has been identified as an outstanding Important Bird Area in the South Indian and Sri Lankan wetlands. 324 species of vertebrates have been recorded in the national park, which includes 32 species of fish, 15 species of amphibians, 48 species of reptiles, 197 species of birds and 32 species of mammals. 52 species of butterflies are among the invertebrates. The wetland habitats in Bundala harbors about 100 species of water birds, half of them being migrant birds.

The greater flamingo Phoenicopterus roseus which visits in large flocks of over 1,000 individuals, from Rann of Kutch of India is being the highlight. Waterfowl (lesser whistling duck Dendrocygna javanica, garganey Anas querquedula), cormorants (little cormorant Phalacrocorax niger, Indian cormorant P. fuscicollis), large waterbirds (grey heron Ardea cinerea, black-headed ibis Threskiornis melanocephalus, Eurasian spoonbill Platalea leucorodia, Asian openbill Anastomus oscitant, painted stork Mycteria leucocephala), medium-sized waders (Tringa spp.), and small waders (Charadrius spp.) are the other avifaunal species which are present in large flocks. Black-necked stork Ephippiorhynchus asiaticus, lesser adjutant Leptoptilos javanicus and Eurasian coot Fulica atra are rare birds inhabit in the national park.

A few Asian elephants (Elephas maximus) still inhabit the forests of Bundala. Other mammals seen in the park are toque macaque Macaca Sinica, common langur Presbytis entellus, jackal Canis aureus, leopard Panthera pardus, fishing cat Felis viverrinus, rusty-spotted cat Felis rubiginosa, mongoose Herpestes spp., wild boar Sus scrofa, mouse deer Tragulus meminna, Indian muntjac Muntiacus muntjak, spotted deer Cervus axis, sambar C. Unicolor, black-naped hare Lepus nigricollis, Indian pangolin Manis crassicaudata, and porcupine Hystrix indica.

Bundala harbors various forms of fishes including saltwater dispersants Anguilla bicolor, marine forms Ambassis gymnocephalus, brackish water forms Chanos chanos and freshwater forms Channa striata. Bundala’s herpetofauna includes two endemic species, a toad and a snake, Bufo atukoralei and Xenochrophis asperrimus. Among reptiles is mugger crocodile Crocodylus palustris, estuarine crocodile Crocodylus porosus, common monitor Varanus bengalensis, star tortoise Geochelone elegans, python Python molurus, rat snake Pytas mucosus, endemic flying snake Chrysopelea taprobana, cat snakes Boiga spp. and whip snakes Dryophis spp. The adjacent seashore of Bundala is a breeding ground for all five species of globally endangered sea turtles that migrate to Sri Lanka.