Sugar Glider
The sugar glider ( Petaurus breviceps ) is a small (120g - 160g) arboreal gliding possum with a distribution amongst the many forest types of eastern and southern Australia. Only this smallest petaurid occurs in Tasmania. Its presence in Tasmania is thought to have resulted from an introduction from Victoria. DNA analyses are being undertaken to investigate whether all sugar gliders in Tasmania originally stemmed from these escaped individuals.

Intermediate in size between the tiny feathertail glider ( Acrobates pygmaeus ) and the greater glider ( Petauroides volans ), the sugar glider can plane for at least 100 m. It leaps from a tree, spreading the membranes (patagium) which extent on each side of the body from the fifth finger to the first toe of the foot, steering and maintaining stability by the long bushy tail and by varying the curvature of the right or left membrane. Just before landing the sugar glider 'stalls' and lands on all fours. The scientific name means 'short-headed rope-dancer' and refers to its quick movements on tiny twigs high up in the canopy.

Seven subspecies of P. breviceps  have been recognised: P.b. longicaudatus  occurs in Queensland, P.b. ariel  in the Northern Territory, P.b. flavidus  in southern New Guinea and West Irian, P.b. tafa  in the Owen Stanley Range of New Guinea, P.b. papuanus  in northern New Guinea and West Irian, P.b. biacensis  on Biak Island and West Irian. P. breviceps breviceps  extends from Tasmania to just south of the Tropic of Capricorn and densities may reach 10 individuals per hectare where conditions are favourable.

Male sugar gliders tend to be larger (115-160g) than females (100-135g). Adult males and females have a head-body length of 15 -20 cm (smaller towards north). Sugar gliders can live for at least 9 years in the wild (in Tasmania) and 12 years in captivity .

The sugar glider is a highly social species and forms groups up to 7 individuals. My work at the University of Tasmania has shown that, at least in captivity, male as well as female sugar gliders establish strong enduring hierarchies and that father and son cooperate in maintaining their social status and care of young. Colonies live in tree hollows, emerging at dusk to forage for arthropods, honeydew, nectar, pollen, Acacia   gum and Eucalyptus  sap. Gum from Acacia mearnsii   is important in its diet, particularly in autumn and winter when it makes the bulk of the diet. Their presence in forests might ensure the demise of pests such as the Christmas beetle. In captivity, sugar gliders can be maintained on a varied diet of fresh fruits, protein mix, cereals, nuts, honey and mealworms.

Mating occurs in July /August so that females suckle young in spring and early summer when food especially insects for their protein needs is copious. P. breviceps have four mammae and often have twins. Triplets only rarely occur and quadruplets are not known. Young remain in the pouch for about 70 days and are then deposited in the nest for a further 30-40 days. When about 110 days old, the young begin to leave the nest to forage, usually accompanying their mother or father. In captivity females can produce up to three litters per year. In the wild they might have a second breeding season when conditions are favourable.

The sugar glider uses a range of calls, including a shrill yapping which is often heard when a predator is near by, a sharp shriek which is emitted when individuals fight and a distinct gurgling chatter is emitted by individuals disturbed in their nest. However, despite the fact that they are rather inquisitive and might even defend food sources against much larger animals, their presence often remains unnoticed. Owls, quolls, kookaburras, cats and in the northern part of Australia goannas and snakes are assumed to prey on sugar gliders but except for cats predation is seldom observed .

Male sugar gliders possess two large dermal scent-organs, the frontal gland overlying the frontal bone between the eyes and the gular gland at the base of the neck on the ventral side. With these glands the dominant individuals mark all clan members and surroundings. Research conducted at the University of Tasmania revealed a positive relationship between high concentration of circulating testosterone and scent-gland development as well as a positive relation between dominance rank and plasma testosterone levels. My work has shown that clans consist of highly related individuals and that related males form amicable relationships to each other. In Petaurus breviceps , olfactory communication appears to serve primarily to produce a group odour which marks areas used by members of the group to exclude other groups. Members of a colony appear to recognise each other by smell and, in the wild and in captivity, will readily attack and viciously bite individuals from other colonies. In captivity foreign individuals introduced to an already established group might get killed by residents of the same sex.

Although sugar gliders are relatively common in the areas where they occur, they are still vulnerable to the effects of logging and fire. Retention of interconnected systems of suitable forest and woodland habitat is essential for their conservation in agricultural areas and adequate reserves such as national parks and forest reserves might be required to ensure their continued survival in the long term. Individuals may huddle in leaf-lined nests in tree hollows at night and colonies may be larger in winter than in summer in temperate environments, which is presumably a response to low ambient temperatures. Individuals may also undergo extended bouts of torpor that greatly reduce the metabolic costs during periods of low ambient temperature or food shortage.

Prepared by Birgitt S. Klettenheimer
Department of Zoology, University of Tasmania and
Zoologisches Institut I, University Erlangen-Nuernberg, Germany