Amphibia
Despite Australia’s aridity endemic frogs are widespread, but in trouble. Since 1980 seven species have vanished from a total of 240 in Australia. In the Berowra Creek catchment 36 species are expected ranging from; the common eastern froglet (Crinia signifera) that is plain brown, found in most water bodies, and is less than 2cm long, to the green tree frog (Litoria caerulea) that is up to 11cm long and quite rare. The red-crowned toadlet (Psuedophryne australis) and the giant burrowing frog (Heleioporus australiacus) are both listed as vulnerable. They have a similar restricted distribution with the toadlet essentially confined to the Sydney Basin. Neither species tolerate polluted water and toadlet habitat is limited to saturated clay soils and waterholes formed on thin shale layers in the Hawkesbury Sandstone. The best of these sites are drains on the edge of fire trails.
Rare green tree frog (Litoria caerulea).
Vulnerable red-crowned toadlet (Psuedophryne australis), a geologically limited species.
Fish and marine mammals
Where there is permanent flow of clean water in creeks in the sandstone landscape both long-finned (Anguilla reinhardtii), and short-finned (Anguilla australis) eels are found, along with several gudgeon (Philypnodon sp. and Gobiomorphus), Australian smelt (Retropinna semoni), two species of spiny crayfish or yabbies (Euastacus spinifer and E. australiensis), and at least 110 familes of macroinvertebrates. Common galaxias (Galaxias maculatus), known in New Zealand as inanaga or whitebait, lays eggs amongst the vegetation at the highest tide level in estuaries. These hatch on the next spring tide and the juvenile fish head out to sea before repeating the cycle. All of these fish are small, but Australian bass, (Macquaria novemaculeata) that were reintroduced to Berowra Creek after sewage treatment was improved can grow to 60cm. At least four species of exotic fish have become established including carp (Cyprinus carpio), tiny predatory mosquito fish (Gambusia affinis), and a range of other exotics released from aquaria.
In the upper parts of the estuaries; sea mullet (Mugil cephalus), yellow-fin bream (Acanthopagrus butcheri), and common toadfish (Tetractenos hamiltoni) are found, and diversity increases as the water becomes more saline. The Hawkesbury River is well known for producing mulloway (Argyrosomus japonicus) as large as 40kg in weight. About 600 fish species are recorded in Sydney Harbour and the river would be similar. On Barrenjoey Headland the Australian fur-seal (Arctocephalus pusillus) has established a small colony, and the coastal headlands are good locations for spotting humpback whales (Megaptera novaeangliae) on their annual migration between Antarctic and Pacific waters.
Australian fur-seal (Arctocephalus pusillus) on rocks at Barrenjoey. Hunted to near-extinction in the 19th Century this colony was recently established near the northern limit of distribution.
