The common ringtail occurs along the entire length of the eastern seaboard of mainland Australia and in the south-west corner of Western Australia. This Tasmanian sub-species is found in Tasmania and the Bass Strait Islands. Like all ringtail possums, the common ringtail possum has a strongly prehensile tail which acts as a fifth limb, and which is carried tightly coiled when not being used. It can be distinguished from the brushtail by the light covering of fur on its tail, as well as the white tail tip. It also has as two thumbs on each front foot which helps them to grip in the trees. The soles of the feet and the underside of the tail is hairless which also helps them to grip on the branches. The short fur is grey-brown on the back with white underneath. When immature, the Common Ring-tailed Possum is reddish brown. They weigh about 700-1100g and its head and body are approximately 30-35cm. Its tail is also 30-35 cm long.
Spherical nests about the size of a football, called dreys, are constructed from bark and grass among the dense canopy of the understorey. The male and female build the nest together, carrying grass, leaves and shredded bark curled up in their tails. The female has four teats but normally only rears two young. When born, the joeys are hairless and about the the size of a jellybean, and leave the pouch when they are about 4 months of age, travelling on the mother’s back. The father also carries young on his back. The young are fully weaned after 6 months of age. The male-female bond usually carries from one breeding season to the next, although the male may mate and associate with a second female in a different part of its home range after the first. Breeding seasons vary in different parts of Australia.
The Ring-tailed Possum is a very social, nocturnal animal with very good night vision. Is found in rainforests, shrubby woodlands, eucalypt forests, coastal shrub and suburban gardens, even occuping roofs of houses. It has a soft, high pitched twittering call. Unlike the Brushtail possum, is strongly aboreal, spending little time on the ground. The Ringtail is unusual among possums in being an active nest builder. The Ringtail may build as many as five nests amongst dense undergrowth in its home range, and will move readily from one to another taking its young with it. They will sleep in these nests during the day. Ringtail possums live in family groups which usually contain a male, one or two females and the young from the previous year. These young do not become adult until they are eighteen months old when they leave the group to form their own families. Family groups tend to nest and forage together until the young disperse.
The ringtail feeds on leaves, as well as flowers. The ringtail is well adapted to a diet of eucalypt leaves, apparently being capable of detoxifying the tannins and phenols in the animal's caecum (a part of the gut). The low metabolic rate of the species is believed to compensate for the relatively low energy yield of its diet.
Common ringtail possum populations severely declined during the 1950s. However, populations seem to have recovered in recent times. Because they are largely arboreal, common ringtail possums are particularly affected by deforestation in Australia.