Mammals present within the park include western grey kangaroo, common brushtail possum, common ringtail possum and echidna. The lesser long-eared bat and the southern forest bat.
You’ll see all kinds of birdlife in the Onkaparinga River Natiopnal Park, particularly if you take a few moments to be still. There is a diverse range of species that live in, or visit, the park – many of conservation significance. Hunting birds, such as the peregrine falcon, scour the landscape in search of birds, small mammals and lizards. You’ll probably hear the yellow-tailed black cockatoo long before you see one, their raucous cries announce their presence well in advance.
Approximately 20 fish species are recorded for the estuary and river. The major fish species include jumping mullet, black bream and yellow-eye mullet. Algae, molluscs and garweed form the major diet of the fish species.
Amphibian records include: common froglet, banjo frog, spotted marsh frog and brown tree frog. At least 20 reptile species have been recorded in the reserves. These include cunningham's skink, eastern bearded dragon and barking gecko.
Common butterfly species include: meadow argus, cabbage white, saltbush blue, australian painted lady, common grass-blue and lesser wanderer. Gahnia filum sedge-lands in the estuary may provide habitat for populations of the endangered yellowish sedge-skipper.