Yellow-bellied Glider

 (Petaurus australis)

by
Keith Bellchambers

Introduction 

The Yellow-bellied Glider (Petaurus australis) is one of the largest gliding possums in Australia, the most loudly vocal, the most capable glider, and yet, it is the least known and least studied member of its family. 

Description 


The average sized animal has a head-body length of 30cm with a tail approximately 45cm long. The species is characterised by a short head with a pointed muzzle and long oval ears. The head and body are grey-brown with a darker stripe down the centre of the back. The belly varies from creamy-with to orange. The gliding membrane on the flanks extends from wrist to ankle. It has a long and bushy tail, which is grey at the base and black on the tip. Hands and feet are black. 

Distribution 

The species is restricted to tall, mature Eucalypt forests in temperate to subtropical regions of eastern Australia which receive high rainfall. The isolated northern Queensland population lives only in dense forests at high altitudes. The range of the species was recently extended into South Australia where an individual was captured in the Caroline Forest Reserve in April 1981. Prior to this capture, it was not thought to occur in South Australia. 

Diet 

As the species is poorly studied there is some confusion over what the species actually lives on. It seems the species lives primarily on tree exudates and, to a lesser extent, insects, and nectar and pollen when available.  The animal is fairly restricted in the species of trees on which it feeds, with the main species being the Rough-Barked Manna Gum (Eucalyptus viminalis) in the south and Red Mahogany in the north. 
To extract the sap from the tree, the animal chews at the bark until it exposes the cambuim. This gnawing tends to form a definite V shape on the tree trunk. As the sap exudes from the cambuim it runs down the V channel and collects in the notch at the base where it can be readily licked up. Trees can become quite scarred over a number of years as ‘sweet’ trees are continually fed upon. 
Utilisation of eucalypt sap, from a limited range of tree species and individuals, as a major dietary item may partially explain the rarity, irregular distribution, and nomadism or extensive home range of the species. 


Breeding 

A high sap and low insect diet in the species would imply a restricted protein intake, and if correct, would also explain the species’ observed low fecundity. 
Females have two nipples in the pouch which is incompletely divided into two compartments by a longitudinal septum. The single young is born usually between November and May and is carried in the pouch for about 100 days. It is left in the nest for a further 60 days, after which it fends for itself. 
This species has a number of complex vocalisations which it uses in different activities. Nocturnal calling patterns are apparently most influenced by the weather conditions on the night. Various activities appear to be associated with calling rate and these include the amount of gliding. 
Apart form providing contact and location information, the calls probably advertise the callers’ sex, age and social status. 


Status in South Australia 

As mentioned previously the species was first recorded for this state in 1981. This capture was made after a limited trapping exercise by Barry Grigg of the Woods and Forests Department in the South-East who had been suspicious of tree damage in a block of native scrub in the Caroline Forest Reserve for a number of years. 
The previous, most westerly report of the species was a locality known as ‘Post and Rail’ in the Glenelg National Park, Victoria. 
This area in which the new record was trapped is an area of reserved natural forest of 188 hectares, dominated by Manna Gum (E. viminalis), Snow Gum (E. pauciflora) and Black Wattle (Acacia melanoxylon) with a bracken and grass understorey. The area is surrounded on all sides by introduced pine plantations and is 1.5km from the nearest block of natural vegetation. 
Since the initial capture, several more animals have been observed while spotlighting and numerous vocalisations have been heard in the block. Scattered trees with V notches trunks have also been located in several other localities in the South-East, so with some intensive searching the range may be extended even further into South Australia. 

 

Yellow-bellied Glider in Captivity 

Very little data is available on this species in captivity. No available information on breeding, gestation or the development of young. 
It is an active, arboreal, nocturnal animal which is capable of gliding up to 115 metres, so it should be housed in roomy quarters that provide sufficient space for them to carry out their nocturnal activities. Any enclosure should be at least 75m x 4.5m and be quite high as they dislike descending close to the ground. 
Aerial runways (e.g: limbs, branches and vertical logs) providing a great variety of possible aerial pathways near the top of the enclosure are important and necessary components in any enclosure set up for these active marsupials. 
In their nocturnal habitat they nest in hollows high in tall trees. They occasionally add to the comfort of the nest by adding leaf and bark nests. In captivity they should be given hollow logs or nest boxes located near the top of the enclosure. 
They are best kept in pairs and individuals have been known to survive in captivity for up to 10 years. 
Individuals of this species kept at Fleay’s Fauna Sanctuary in Queensland are fed the following diet:  Bread and milk with melon jam, gum blossom, honey and slabs of sapwood from preferred Eucalypt trees.  


Conclusion 

Because of its low numbers and restricted habitat requirements the species is considered rare and endangered. The species faces many problems in future survival over a wide area because of severe pressures being put on its’ habitat. The population in North Queensland is declining due to timber-getting and clear-felling for agriculture. 
The provision of many small sanctuaries in areas of State forest known to be occupied by the species, may be the best way to protect the species throughout its range which would have been seriously reduced by the large fires in 1983 in Victoria

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