The Green-tree Snake, Dendrelaphis punctulatus, and Brown-tree Snake, Boiga irregularis, both still occur in leafy residential areas and bushland reserves in the northern shore suburbs of the harbour. There are reports of Green-tree Snakes living in the roofs of suburban houses.

Both are relatively long (1.5-2 m in length) and as their common names imply, are largely arboreal species that spend time foraging in trees. The two species are easily distinguished by colouration and head shape. The Brown-tree Snake is reddish-brown with narrow dark cross-bands and has a broad angular head, it a nocturnal species and is rarely seen active during the day. The Green-tree Snake is olive-green overall with a slightly darker head; it has a long narrow head and is often seen moving about during the day. When it is alarmed the Green-tree Snake inflates its body and shows a pattern of light blue spots, the colour of the skin between the scales.

The Green-tree Snake is a non-venomous species whereas the Brown-tree Snake has venom glands and delivers the venom via grooves in enlarged teeth in the rear of the mouth, hence the term 'rear-fanged' is applied to this species.