Greater gliders are found along the eastern coast of the Australian mainland, from eastern Queensland to southern Victoria (Nowak, 1999; Troughton, 1966).
Biogeographic Regions: australian (Native )
Greater gliders are the largest of the gliding possums. Females have a well-developed pouch and two mammae. P. volans are about the size of a domestic cat, weighing 1-1.5 kg as adults. The head and body length is 300-480 mm and the tail is 450-550 mm long (Nowak, 1999). These marsupials have a short snout and large round ears covered by thick fur (Strahan, 1995). The patagium, which is also covered with fur, extends from the knee to the elbow, (unlike the Petauridae, in which it extends from the ankle to the wrist), giving the glider a triangular shape when in the air (Berra, 1998). The long, furred tail, which is not prehensile, is used as a rudder (Grzimek, 1972). Color varies more than that of any other marsupial. The very long, dense fur is typically brownish-black, but can range from pure black with a creamy underside, to dusky browns and grays, cinnamon, red, yellow, and completely white (Grzimek, 1972; Troughton,1966).
Range mass: 1 to 1.5 kg.
Range length: 300 to 480 mm.
Other Physical Features: endothermic ; bilateral symmetry
Average basal metabolic rate: 3.191 W.
Habitat and Ecology
Greater gliders are generally restricted to fairly expansive tall eucalyptus forests, and are never found in the rainforest (Grzimek, 1990). Patches of old growth must be at least 20 ha to sustain a population (Possingham, et al. 1994). Greater gliders are associated with high basal areas of over-story, and they need large patch sizes of old-growth forest. They are most often found in sites containing many trees with hollows. A single glider may use 4-18 den sites (Incoll et al., 2001; Lindenmayer et al., 1993).
Habitat Regions: temperate
Terrestrial Biomes: forest
Greater gliders are folivores, feeding almost entirely on eucalyptus leaves that they break down with bacterial fermentation in an enlarged cecum (Berra, 1998; Lindenmayer et al., 1999; Possingham et al., 1994). This specialized diet means they are very difficult to keep in zoos (Grzimek, 1990). Greater gliders rarely need to drink (Strahan, 1995).
Plant Foods: leaves
Primary Diet: herbivore (Folivore )
The role of these gliders in the ecosystem has not been evaluated. However, they do eat eucalyptus leaves, maing the energy stored in those leaves available to their predators.
Owls may represent the largest threat to gliders. Powerful owls and sooty owls both prey upon them. Dingos and introduced foxes also take P. volans. Because they are gliders, it is likely that they can escape predators by "flying" away.
- powerful owls (Ninox strenua)
- sooty owls (Tyto tenebricosa)
- dingos (Canis lupus dingo)
- red foxes (Vulpes vulpes)
Canis lupus dingo
This list may not be complete but is based on published studies.
Ecology and conservation
Logging has been demonstrated to impact on Greater Glider (eg Kavanagh et al 1995) with the highest densities occurring within unlogged old growth forests over logged, regrowth forets.
Greater Gliders are a major prey item for the Powerful Owl and Powerful Owls have the potential to significantly decimate Greater Glider populations by up to 90% (Kavanagh 1988).
Comport, S, Ward, S and Foley, W (1996) Home ranges, time budgets and food-tree use in a high-density tropical population of greater gliders, Petauroides volans minor (Pseudocheiridae : Marsupialia), Wildlife Research 23, 401-418.
Kavanagh, R (1988) The impact of predation by the powerful owl, Ninox strenua, on a population of the greater glider, Austral Ecology 13, 445-450.
Kavanagh, R, Debus, S, Tweedie, T and Webster, R (1995) Distribution of Nocturnal Forest Birds and Mammals in North-eastern New South Wales: Relationships with Environmental Variables and Management History, Wildlife Research 22, 357-377.
Life History and Behavior
Perception Channels: tactile ; chemical
Longevity may be up to 15 years in the wild (Nowak, 1999).
Status: wild: 15 (high) years.
Status: captivity: 15.0 years.
Status: wild: 6.0 years.
Lifespan, longevity, and ageing
Males and females will normally share a den from the onset of breeding until the young emerge from the pouch (Strahan, 1995). Some males are monogamous while others are bigamous, although there is no paternal care given to the young (Nowak, 1999).
Mating System: monogamous ; polygynous
Breeding season begins in March, and a single young is born between April and June. The offspring rides in the mother’s pouch until September, suckling on one of the two teats, then rides on the mother’s back until November or December. In January it reaches the age of independence. Sexually maturity is reached at two years of age. Until weaning, approximately half of the offspring produced are male. After the weaning period, the proportion of the population that is male drops precipitously to 39% (Hand, 1990; Tyndale-Biscoe and Smith, 1969).
Breeding season: Breeding begins in March, and the young is born between April and June.
Range number of offspring: 1 (high) .
Average age at sexual or reproductive maturity (female): 2 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous
Average birth mass: 0.273 g.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (male)
Sex: male: 639 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 639 days.
As in all marsupials, the young are born highly altricial in most respects. Development must be completed in the mother's pouch, rather than in the uterus, as it is in placental mammals. The single offspring is nursed in the pouch until September, when the young glider emerges at 150 g to ride on its mother’s back. In November-December, when about 300 g, the young leaves its mother’s back and becomes more independent. In January, at about 600 g, the young is able to live independently. (Tyndale-Biscoe and Smith, 1969).
Parental Investment: altricial ; female parental care
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1996Lower Risk/least concern (LR/lc)
- 1996Lower Risk/least concern (LR/lc)
Although widespread and abundant in some areas, greater gliders are very sensitive to clear-cuts and fragmentation of their old-growth habitat. Their conservation is entirely dependent upon the responsible management of the old growth forests in which they live (Kavanaugh and Bamkin, 1995; Strahan, 1995). Tyndale-Biscoe and Smith (1969) showed that over 90% of gliders displaced by a clear-cut die rather than establish a new territory in suitable habitat nearby. Greater gliders may have difficulty migrating through unfavorable habitat for several reasons. They are specialist feeders, and only eat the leaves of some eucalyptus trees. They only carry limited quantities of body fat, and are likely to undergo rapid changes in body condition under adverse conditions, such as with dispersal. They are also very clumsy on the ground, and so have difficulty in crossing open tree-less areas (Lindenmayer et al., 1999).
CITES: no special status
IUCN Red List of Threatened Species: least concern
Relevance to Humans and Ecosystems
Since greater gliders require large patches of old growth habitat (Possingham et al., 1994), their needs can conflict with those of humans who wish to cut the trees for timber.
Although the fur is long and thick, it is rather loose and soft which makes it difficult to work with. Luckily for greater gliders, fur traders rarely wanted their skins (Strahan,1995).
The greater glider (Petauroides volans) is a small gliding marsupial found in Australia. It is not closely related to the Petaurus group of gliding marsupials but instead to the lemur-like ringtail possum (Hemibelideus lemuroides), with which it shares the subfamily Hemibelideinae.
The greater glider is nocturnal and is a solitary herbivore feeding almost exclusively on Eucalyptus leaves and buds. Like its relative the lemur-like ringtail, the greater glider is found in two forms: a sooty brown form, or a grey-to-white form.
Anatomy and physiology
Greater gliders have a head and body about 39 to 43 centimetres (15 to 17 in) long, with the females being generally larger than the males. Their body is covered with a shaggy coat of fur that increases their apparent size, and the tail is long and bushy, ranging from 44 to 53 centimetres (17 to 21 in). The head is short, but with a pointed muzzle, and large ears fringed and backed with long fur. Each side of the body bears membranes stretching between the elbow and the ankle, that give the animal the ability to perform controlled glides. This is in contrast to other gliding marsupials (such as the sugar glider) that have gliding membranes stretching from the wrists to the ankles.
The feet have strongly recurved claws to grip onto bark or other surfaces. There are five toes on each foot, with the first toe on the hind foot, and the first two toes on the fore foot, being opposable.
The fur is soft and up to 60 millimetres (2.4 in) long; the colour is variable within the same populations, ranging from white to brown and charcoal. Body mass varies clinally from about 1,600 grams (3.5 lb) in southern Victoria to about 600 grams (1.3 lb) in north Queensland.
Heat management in the greater glider is performed by licking extremities and the ventral body surface, with direct evaporation being the main method of the cooling. Furthermore, the glider can use its gliding membranes to reduce heat loss by increasing the layer of insulation at the skin surface. However, the greater glider is not well equipped to handle high ambient temperatures, as it inefficiently uses water for evaporation via salivation even though arboreal habitats are often limited in water accessibility.
The greater glider can digest low nutrient foliage, specifically eucalypt leaf matter, which contains a variety of phenolic and terpenoid compounds and a high concentration of lignified fibre. Animals can digest about 50–60% of the leaf during its passage through the gut  The gut has a specialized caecum that is contains a population of bacteria that ferment food residues that remain undigested in the small intestine. For a population in a eucalypt forest near Maryborough, Queensland, it has been calculated that their daily energy intake is about 1130 kJ, which is provided by about 45 to 50 grams (0.099 to 0.110 lb) of dry matter daily.
Mature females will give birth to a single progeny, each year which is typically born in late autumn or early winter. The underdeveloped offspring will then spend the next four months within the pouch of the mother to suckle and develop. It will remain within the security of the pouch until about nine months of age.
Distribution and habitat
The greater glider is found in southern Queensland, eastern Australia, southeastern New South Wales, and the montane forests of the Victorian central highlands. The Greater Glider is usually tracked via spotlighting on transects (considered to underestimate the actual population size), radio tagging and owl-call playback.
There are two recognised subspecies:
- Petauroides volans volans – temperate and subtropical Victoria, NSW, and Queensland
- Petauroides volans minor – tropical Queensland
The greater glider chooses habitat based on several factors. A large factor determining habitat choice is the presence of specific species of eucalypt. Distribution levels are higher in regions of montane forest containing Manna Gum (E. viminalis) and Mountain Gum (E. dalrympleana, E. obliqua). Furthermore, the presence of E. cypellocarpa appears to improve the quality of habitat for the greater glider in forests dominated by E. obliqua. Another factor determining population density is elevation. Optimal levels are 845 m above sea level. Within a forest of suitable habitat, they prefer overstorey basal areas in old-growth tree stands.
The greater glider is primarily nocturnal, spending the night foraging in the highest parts of the forest canopy. During the day, it spends most of its time denning in hollowed trees, with each animal using up to twenty different dens within its home range. The dens are often lined with leaves and strips of bark. This is why spotlighting has become a popular way of locating members of a population; when a strong light is directed at the eyes of a glider, the observer will see two bright red orbs reflecting back.
Within forests, males and females will have home territories and set borders between other members. For males, home territory ranges from 1.4 to 4.1 hectares (3.5 to 10.1 acres) while that of females is only 1.3 to 3.0 hectares (3.2 to 7.4 acres). Although home ranges may overlap, the animals remain generally solitary outside of the breeding season, and only rarely interact. In large and small patches of forest, the home territories will respectively be larger and smaller.
The gliding posture of the greater glider is unique among marsupials. The forelimbs are folded so that the wrists are tucked under the chin, giving the patagium a triangular outline when outstretched. The animal regularly glides between high trees, and is able to use the tail to assist in steering. They avoid travelling along the ground whenever possible, and are slow and clumsy if forced to do so.
Greater gliders subsist almost entirely on the young leaves and flower buds of select eucalypt species, especially Eucalyptus radiata, Eucalyptus viminalis, and Eucalyptus acmenoides. Young leaves are preferred because they have higher concentration of nitrogen and lower concentration of lignocellulose (acid-detergent fibre). Overall, the eucalypt leaves are a poor source of nutrients.
Because of its night time activities, a natural predator on the glider is the Powerful Owl (Ninox strenua). It hunts by concentrating in pockets within their relatively large home range until populations of prey are depleted to a level that causes the owl to shift hunting grounds. Other predators include feral cats, which are not native to Australia, being introduced with the arrival of Europeans.
The breeding season for greater glider is relatively brief, lasting from February to May, with births occurring between April and June. Females have a relatively well-developed pouch, opening towards the forward part of the animal, and containing two teats. Only a single young is born each year.
At birth, the young weighs only around 0.27 grams (0.0095 oz), but it does not begin to leave the pouch for about four months, by which time it is already furred and well developed. After leaving the pouch, the mother may carry it about on her back, until it is weaned at about seven months of age. The young are independent at nine months, and reach sexual maturity between 18 months and two years after birth.
Greater gliders have been recorded as living for up to fifteen years.
Although previously thought to be related to the other gliding possums, the greater glider is now known to be most closely related to the ringtail possums, and especially to the lemur-like ringtail possum, from which its ancestors diverged around 18 million years ago. In contrast, it diverged from the gliding possums much earlier, around 36 million years ago. Fossils of greater gliders are known from the late Pleistocene onwards, and show that the animal was once more widespread, also being found in at least some areas of South Australia.
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