Mammals
Greater Glider
Petauroides volans · also called greater glider, clumsy possum
The greater glider is the largest gliding marsupial in the world, a cat-sized animal with enormous fluffy ears and a long trailing tail that launches from the top of one eucalyptus and sails as far as 100 metres to the next. It eats almost nothing but gum leaves, runs its body on a famously tight energy budget, and has declined so fast that in 2022 it was listed as Endangered.
Overview
Greater gliders live in the tall eucalyptus forests of eastern Australia, from the wet tropics of Queensland south to central Victoria. Head and body measure about 35–45 cm, with a furry tail nearly as long again, and adults weigh between 900 g and 1.7 kg. The fur is soft and thick and ranges from sooty charcoal to creamy white, sometimes within a single patch of forest.
A glider built differently
Unlike sugar gliders and flying squirrels, whose gliding membrane runs from wrist to ankle, the greater glider’s membrane runs from elbow to ankle. It holds its forearms tucked while airborne, forming a triangular shape, and steers with its long tail. A launched glide typically covers 20 to 100 metres, losing height the whole way, and ends with the animal swinging its hind legs forward to land feet-first on a trunk.
Living on gum leaves
Eucalyptus leaves are tough, low in nutrients, and laced with oils and tannins. A diet of almost nothing else forces the greater glider into an economical way of life: a low body temperature, a slow metabolism, deliberate movements, small home ranges of only a few hectares, and very little drinking, since it gets most of its water from foliage. It often feeds in just a handful of preferred trees, which is why losing those trees hits it hard.
Hollows that take a century
By day the greater glider sleeps in a tree hollow, and one animal may rotate between many hollows across its range. Hollows large enough for it form only in old eucalyptus trees, over more than a hundred years. Logging and land clearing strip these out far faster than new ones appear, leaving even uncut forest short of shelter.
Status
Genetic research in 2020 split the greater glider into three species, each with a smaller range than the original. All are declining. Forest clearing and logging, the massive bushfires of 2019–20, and rising heat that its physiology cannot buffer have driven steep local losses, and the animal was uplisted to Endangered in 2022. Conservation now centres on keeping forests standing, protecting old hollow-bearing trees, linking habitat, and dampening fire.
Greater Glider: common questions
How is the greater glider different from a sugar glider?
They are not close relatives and only look similar because both evolved gliding. The greater glider is far larger, roughly the size of a domestic cat once its tail is included, while a sugar glider is small enough to sit in a cupped hand. Their gliding membranes are built differently, running from elbow to ankle in the greater glider and from wrist to ankle in the sugar glider, which changes the posture each holds in the air. Their diets are different too, the greater glider being a strict eucalyptus-leaf specialist while the sugar glider is an omnivore that takes sap, nectar, and insects. The greater glider is also silent and solitary, whereas sugar gliders are social and vocal.
Why is the greater glider now endangered?
Several pressures have combined quickly. Large areas of its forest have been cleared or logged, which removes both its feeding trees and the old hollow-bearing trees it must shelter in, and those hollows take more than a hundred years to form. The catastrophic bushfires of 2019 and 2020 burned a large fraction of its remaining habitat in a single season. On top of this, the greater glider copes poorly with heat, and rising temperatures and more frequent extreme hot spells push animals beyond what their low-energy physiology can handle. Because it cannot travel far on the ground, fragmented forest also leaves populations stranded. It was uplisted to Endangered in 2022.
What does a greater glider do all day?
Very little that uses energy. It spends the daylight hours asleep, curled in a tree hollow, and emerges after dark to feed in the canopy of a small number of favoured eucalyptus trees. It moves deliberately along branches, glides to the next tree when it needs to cross a gap, and returns to a hollow before dawn. It does not build nests of vegetation, does not store food, rarely comes to the ground, and generally does not travel outside a home range of only a few hectares. This economical lifestyle is a direct consequence of how little energy eucalyptus leaves provide.
Can greater gliders be kept in captivity or bred to boost numbers?
It is very difficult. Their absolute dependence on fresh eucalyptus foliage, often from particular species and particular growth stages, makes them hard to feed, and they are sensitive to heat and stress. Only a handful of institutions have held them successfully. For these reasons conservation effort focuses mainly on protecting standing forest, retaining old hollow-bearing trees during any logging, creating habitat corridors, installing nest boxes as a stopgap where hollows have been lost, and reducing the frequency and intensity of fires rather than on captive breeding.