Mammals and reptiles

Most mammals, reptiles and amphibia are cryptic and/or nocturnal, so their traces (burrows, tracks, scats, nests, and feeding sign) are easier to find. Sometimes there is a close link between organisms and the geology. For example, on the sandstone plateaus the endangered broad-headed snake (Hoplocephalus bungaroides) and velvet geckos (Oedura lesueurii) share the cool spaces under loose sandstone boulders.  The snakes feed on the gecko and a study in Ku-ring-gai Chase and Muogamarra revealed that this kind of space is also occupied by up to seven invertebrates.

In the coastal heath and woodland, monitor lizards (Varanus sp.) are widespread and a clue to their presence can be a burrow excavated into a termite mound near the ground, where eggs can over winter at a stable temperature.

Fourteen snake species are recorded within the KGR and some may be seen basking in spring sunshine on warm surfaces. These include; eastern brown snake (Pseudonaja textilis), red-bellied blacksnake (Pseudechis porphyriacus), tiger snake (Notechis scutatus), death adder (Acanthophis antarcticus), diamond python (Morelia spilota), and common tree snake (Dendrelaphis punctulatus). Several of these are nocturnal hunters.

In wetlands and along streams, the eastern water dragon (Physignathus lesuerii) makes a noisy splash into the water when disturbed and the eastern snake-necked turtle (Chelodina longicollis), or the short-necked Murray River turtle (Emydura macquarii) can often be seen. In the marine environment green sea turtles (Chelonia mydas) are not uncommon and occasionally, a larger tropical species such as the leatherback turtle (Dermochelys coriacea) arrives. This occurrence of tropical species may be a result of a southerly extension of the East Australian current driven by a warming climate.

About 30 species of monotremes and mammals are known. Echidna (Tachyglossus aculeatus) are common and their crescentic feeding scrapes can be seen in ant or termite nests, and around rotting logs.  Platypus (Ornithorhynchus anatinus) are known but rarely seen. The smallest marsupials are brown antechinus (Antechinus stuartii) and the pygmy possum (Cercartetus nanus), the largest is the eastern grey kangaroo (Macropus giganteus) which were released in Muogamarra in 1976.  The KGR woodlands are not really kangaroo habitat although they have dispersed widely from that release site but are not in large numbers.

The endangered southern brown bandicoot (Isoodon obesulus) is at its northern limit in the KGR. It is restricted to ridgetop heath and woodland. The long-nosed bandicoot (Perameles nasuta) lives in heathlands or forests with sandy soil and is more common, but populations are vulnerable to cats, foxes, vehicles and fire.

Common brushtail (Trichosurus vulpecula) and ringtail (Pseudocheirus preregrinus) possums do well in the marginal urban areas and sugar gliders (Petaurus breviceps) are common in Muogamarra. Eight species of insectivorous bats are widespread and the KGR hosts several large camps of grey-headed flying fox (Pteropus alecto). These are attracted to the late summer flowering of red bloodwoods (Corymbia gummifera). Four native placental rodents are present in the GeoRegion; the bush rat (Rattus fuscipes), the swamp rat (Rattus lutreolus), and the water rat or rakali (Hydromys chrysogaster) with a white tipped tail lives in brackish water in Narrabeen Lagoon and at Bobbin Head. The vulnerable New Holland mouse (Pseudomys novaehollandiae) was rediscovered in Ku-ring-gai Chase in 1967 after having been presumed extinct for a century.  These are nocturnal omnivores that burrow in sandy soil and are similar in appearance to the common house mouse. Populations change rapidly, local extinctions are frequent, and the greatest numbers are found a few years after fire.

The vertebrate fauna now includes exotic brown rats, house mice, foxes, rabbits, feral/ domestic cats, and stray dogs.