Mahogany Sugar Glider

Mahogany Sugar Glider

The mahogany glider is a small gliding possum occurring in Queensland. It is nocturnal, elusive and silent for much of the time. It was described in 1883 from a skin by Charles de Vis, a noted naturalist and amateur geologist who became an early curator of the Queensland Museum. Little more was known about the mahogany glider for over a hundred years and doubts were raised at to whether it actually existed. However, some clever detective work by scientists resulted in the exciting rediscovery of the mahogany glider in 1989 at Barrett’s Lagoon near Tully in north Queensland.

The mahogany glider receives its name from its buff-coloured belly. The top of the head is pale and bears a dark stripe. Fully grown mahogany gliders are around 600 mm long from head to tail-tip and weigh 300-450 g.

The mahogany glider, in common with other gliders, has a fold of skin which stretches between the front and rear legs. This acts as a parachute enabling individuals to glide for distances averaging 30 m and sometimes longer. The long tail is used for stabilisation especially when coming in to land on tree trunks.

Mahogany gliders are much larger than their closest relative, the squirrel glider, with which they may be confused in the wild.

Habitat and Range
Mahogany gliders are restricted to the coastal southern Wet Tropics region of northern Queensland. They live in a narrow and highly fragmented band of lowland sclerophyll forest extending around 140 km from Toomulla, north of Townsville, to Tully and up to 40 km inland. Most recorded sightings have been at altitudes below 120 m. The main canopy and sub-canopy trees are eucalypts, bloodwoods and paperbarks and less commonly swamp mahogany and turpentine with an open mid-stratum of smaller trees and shrubs (e.g. wattles, forest siris, golden parrot tree, black she-oak, pandanus) and a grassy ground stratum in which grass trees may be present. The mahogany glider requires a relatively open forest structure for efficient gliding and tends to avoid dense vegetation such as rainforest.

The mahogany glider forages alone at night feeding on nectar, pollen and sap from over twenty different species of trees and shrubs. It also eats honeydew (a sweet sticky substance excreted by insects such as aphids), insects such as lerps and the arils of wattles (an aril is a protein-rich stringy structure which connect seeds to the pod). Nectar and pollen feeding gliders are known to provide an important ecosystem function as pollinators of tree species such as some eucalyptus and banksia.

Mahogany gliders use hollows in large eucalypts and bloodwoods as dens for sleeping and rearing their young. They den either alone or in pairs and can use up to 10 dens in a single season. Dens are lined with a thick mat of leaves.

Mahogany gliders appear to be socially monogamous. Individuals may den with their mate and actively mark and defend their home ranges by chasing out other individuals. Territories are around 20 ha in size.

Mahogany gliders first breed at around 12–18 months and wean their young after four–five months. They generally raise only one litter per breeding season. A litter usually consists of one or two young, usually born between April and October. After weaning, juveniles of both sexes appear to disperse from the parental home range.

Isolation of populations and decline in habitat quality are major ongoing threats to the mahogany glider. Other causes of mortality include entanglement in barbed wire fencing, road kills and possibly predation by cats. The rufous owl and masked owl are natural predators.

Past clearing for agriculture, grazing, forestry and human settlement has reduced the total area of remaining mahogany glider habitat to around 110,000 ha, less than 20 per cent of the total area considered to be present at time of European settlement. The present population has been estimated to comprise about 1,500 individuals. Lack of suitable habitat in which young animals can disperse may be a constraint on further expansion of the population.

The mahogany glider, being highly mobile, requires more or less continuous vegetation cover to range freely. Infrastructure corridors such as major roads, railway lines and powerlines present barriers to movement as do clearing and settlement patterns in the landscape. A population viability analysis suggests that a minimum of 8,000ha of vegetation containing around 800 individuals is required for a localised population to remain viable. Presently, a number of large discrete patches of habitat survive.

Decline in habitat quality has been occurring through a combination of altered fire regimes (too much or too little), weed invasion and intensive grazing. Loss of habitat has been occurring in situations where sclerophyll forest is developing a rainforest understorey in the absence of fire. This trend is difficult to reverse using conventional management practices and has the potential to contribute to local extinction of mahogany gliders.

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Text © Queensland Goverment (Dept of Environment and Heritage Protection)