While P. australis probably eats mostly nectar and arboreal arthropods, it also removes bark from various eucalyptus trees to get the sugary sap. It makes characteristic V -shaped cuts in the bark that channel the sap to its mouth, placed at the bottom of the V . Average home range was about 0.5 ha., though males extended their range slightly during the breeding season. Each species of Petaurus is social to some extent, and a variety of sounds are produced. All members probably are related and descended from an original colonizing pair.
Groups appear mutually exclusive, territorial, and agonistic toward one another.
One or two dominant, usually older males are responsible for most territorial maintenance, aggression against intruders, and fathering of young. There are a few lone adults, and the young generally leave their natal group at 10-12 months. This species has a complex chemical communication system based on scents produced by frontal, sternal, and urogenital glands of males and by pouch and urogenital glands of females. Each animal of a group has its own characteristic smell, which identifies it to other individuals and which is passively spread around the group's territory. In addition, a dominant male actively marks the other members of the group with his scent.