The best known of Melbourne's mammals, two possum species have adapted remarkably well to suburban environments: the common brushtail (Trichosurus vulpecular) and the common ringtail (Pseudocheirus peregrinus). The variety and luxuriance of plants in Melbourne's well-tended gardens provide a superior diet and greater choice of denning sites than are available in natural vegetation communities, resulting in higher population densities in the suburbs than in natural environments. Both species eat a wide range of plant food, frequently earning the wrath of keen gardeners. Brushtails will feed on the ground on grass, herbs and food scraps, whereas the smaller ringtails avoid the ground, preferring to remain in dense shrubbery, where they are safe from predators such as dogs, cats and foxes. Ringtails are agile leapers from tree to tree and are adept at running along power lines or fences to move between vegetation clumps.
The loud, nasal coughing and hissing calls of the common brushtail possum are a characteristic nocturnal sound throughout Melbourne, particularly during breeding periods in autumn and spring. The delicate, insect-like chirrups of common ringtail possums are less well known, though quite distinctive. Brushtails spend the daylight hours in tree hollows or other cavities; in the suburbs they frequently den in roof cavities and can gain access through gaps as narrow as 7 cm. Ringtails mostly den in dense clumps of vegetation, building dreys composed of dried leaves, bark and twigs, woven into a hollow sphere with a single side entrance.
Six other species of possum are known from the greater Melbourne region. In some outer suburbs with remnant native forest the sugar glider (Petaurus breviceps) persists, and in the tall wet forests of the Dandenong Ranges the mountain brushtail possum (Trichosurus caninus), yellow-bellied glider (Petaurus australis), greater glider (Petauroides volans) and feather-tail glider (Acrobates pygmaeus) can still be found. The eastern pygmy-possum (Cercartetus nanus) formerly occurred in coastal banksia woodland around Port Phillip but has not been recorded for many decades because of the near total destruction of this habitat.
All possums are protected under the Wildlife Act 1975. A 2003 Government Order permits the trapping of brushtails living in buildings; they can be released up to 50 m from the capture site or be taken to a registered vet for euthanasia. Brushtails may also be trapped in parks by licensed possum controllers.