Squirrel glider

Not to be confused with Flying squirrel.

The squirrel glider (Petaurus norfolcensis) is a nocturnal gliding possum^[2] and is one of the wrist-winged gliders of the genus Petaurus.^[3]

Squirrel glider
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Infraclass:	Marsupialia
Order:	Diprotodontia
Family:	Petauridae
Genus:	Petaurus
Species:	P. norfolcensis
Binomial name
Petaurus norfolcensis (Kerr, 1792)
distribution

Habitat

The home range of this species extends from Bordertown near the South Australia/Victorian Border, through south-eastern Australia to northern Queensland. It was thought to be extinct in South Australia since 1939, until a genetic test confirmed they still inhabited the area.^[4]

In south-eastern Australia the squirrel glider lives in the dry sclerophyll forest and woodlands, whilst in Queensland they occupy a wetter eucalypt forest.^[4]

The squirrel glider will make a den in a hollow tree and line it with leaves. Here it will sleep, usually living in groups of one male, 2 females and their offspring.^[5]

Appearance

Like most of the wrist-winged gliders, the squirrel glider is endemic to Australia. It is about twice the size of the related sugar glider (P. breviceps), with a body that is 18–23 cm long and a tail measuring 22–33 cm.^[4] It weighs around 230g or 0.5 lbs^[5] and has blue-grey or brown-grey fur on its back and a white belly. The end of the tail is black and there is a black stripe from the eyes to the middle of the back.^[4] They have a flying membrane that extends from their 5th front toe to the back of their foot on both sides. When they glide their prehensile tail acts as a rudder, allowing them to steer in the direction they want to go.^[6] They can glide up to 50m from tree to tree,^[5] but tend not to glide in captivity.

Reproduction

The breeding season is between June and January and the gestation period is 18 days.^[6] The litter sizes are usually one to two offspring a year,^[5] who will immediately crawl to the mother's marsupium and anchor themselves to a teat where they will stay for about 3 months.^[6][7] The mother will wean her offspring for around 4 months while they stay in the den. They become independent at 10 months and will leave the den; their life expectancy is 4–6 years.^[5]

Diet

Squirrel glider at
Lone Pine Koala Sanctuary

The squirrel glider eats mostly fruit and insects.^[8][9] It also feeds on tree sap, mainly eucalyptus or red bloodwood trees. In order to get the sap the squirrel glider will pierce the trunk of the tree causing sap to flow out of it. It also eats pollen, nectar, leaves, and bark.^[5][10]

Threats

Natural predators of the squirrel glider include owls and introduced predators such as dogs, cats and foxes. Habitat fragmentation and destruction by human agency is also impacting individual populations, however due to large population sizes and occurrence in several protected areas, the species is currently classified as Least Concern by the IUCN.^[1]

Phylogeny

The squirrel glider's closest relatives come from the same genus, Petaurus, and they include the sugar glider (P. breviceps), mahogany glider (P. gracilis), northern glider (P. abidi), Biak glider (P. biacensis) and yellow-bellied glider (P. australis). It is not yet known which species the gliders diverged from. The squirrel glider most likely evolved from a marsupial like a possum that had membranes for gliding. Other animals that have this same ancestor include Striped possum and Leadbeaters possum.

Analogous structures

Squirrel gliders are often mistaken for the flying squirrels of North America. These two species are not related at all, as the flying squirrel is a placental mammal and the squirrel glider is a marsupial (like koalas and kangaroos). Both have an adaptation for tree living as a result of the patagia, which is the skin that extends from their front to hind legs, allowing them to glide between the trees, avoiding predators they might come into contact with on the ground.

Homologous structures

Squirrel gliders are able to curl their tails around branches to hold on. This feature is homologous to the ring tail possum (order of Diprodontia), which use their tail as an extra limb to grab hold of trees (their tail is longer but the squirrel glider's is bushier).