The Common brushtail possum is one of the most commonly seen possums in Sydney, where this animal occurs in urban areas, fearlessly associating with humans. The bushy tail of the animal has a prehensile tip and a naked patch on the under-side, which allows the possum easily grasp tree branches. Front feet possess rather sharp claws. Each of the hind feet has an opposable and clawless first toe, providing good grip. The second and third toes are webbed, equipped with a long and split claw, which is typically used in grooming.
This possum is widely distributed across Australia, Tasmania and many offshore islands such as Barrow Island and Kangaroo Island. The animal is also introduced and fairly common in New Zealand. The Common brushtail possums occur in a wide variety of habitats such as rainforest, woodland, dry eucalypt forest, pine plantations, semiarid areas, urban gardens/parks and, sometimes, treeless areas.
These marsupials are arboreal and solitary animals, marking their home ranges through scent secretions. However, due to a very high number of their populations, they often have overlapping home ranges. In spite of being solitary, Common brushtail possums have been known to display dominance hierarchies with co-dominants of the same sex typically avoiding each other. However, direct aggression among individuals is very rare. These nocturnal animals spend their daytime hours resting in hollow logs or trees, while those in urban areas may rest wherever they feel secure, even in attics of houses. Brushtail possums are highly vocal animals. They interact with conspecifics through a wide variety of calls such as clicks, grunts, hisses, alarm chatters, guttural coughs or screeching.
Common brushtail possums exhibit polygynandrous (promiscuous) mating system, in which both males and females have multiple mates. Mating usually depends on location. Thus, in some areas such as northern Australia, they usually breed throughout the year. In other areas, these possums mate with peak periods, occurring in spring, from September to November, and during the autumn months, from March to May. Meanwhile, in some areas of their range, they can give births in both seasons. Gestation period lasts for 16 - 18 days, yielding a single, tiny baby, which climbs into the pouch of its mother without any help. The baby remains in the pouch for about 4 - 5 months, after which it is left in the den or may ride on the back of its mother until 7 - 9 months old. Females of this species are ready to mate at 12 months old, while males are mature at 2 years old.
Presently, the Common brushtail possum suffers from loss of its natural habitat. The animal is hunted by dingoes, foxes, cats and dogs. The Common brushtail possum also competes for food and home sites with other possums and animals.
According to IUCN, the Common brushtail possum is locally abundant and widespread throughout its range but no overall population estimate is available. Although this species is currently classified as Least Concern (LC) on the IUCN Red List, its numbers are decreasing.