The Sugar Glider (Petaurus breviceps)
is a small gliding possum native to eastern and northern mainland
Australia, New Guinea, and the Bismarck Archipelago, and introduced
to Tasmania.
It is around 16 to 20 cm (6.3
to 7.5 in) in length, with a slightly longer tail, and weighs
between 90 and 150 grams (3 to 5.3 oz). The fur is generally
pearl grey, with black and cream patches at the base of the
pink ears. The tail tapers only moderately and the last quarter
of it is black, often with a white tip. The muzzle is short
and rounded. Northern forms tend to be brown coloured rather
than grey and, as predicted by Bergmann's Rule, smaller.
The most noticeable features of its anatomy, however, are
the twin skin membranes called "patagium"s which extend from
the fifth finger of the forelimb back to the first toe of
the hind foot. These are inconspicuous when the Sugar Glider
is at rest it merely looks a little flabby, as though it had
lost a lot of weight recently but immediately obvious when
it takes flight. The membranes are used to glide between trees:
when fully extended they form an aerodynamic surface the size
of a large handkerchief.
Sugar Gliders can occupy any area where there are tree hollows
for shelter and sufficient food. Their diet varies considerably
with both geography and the changing seasons, but the main
items are the sap of acacias and certain eucalupts, nectar,
pollen, and arthropods. They are difficult to see in the wild,
being small, wary, and nocturnal, but a sure sign of their
presence is the stripping of bark and tooth marks left in
the soft, green shoots of acacia trees.
The gliding membranes are primarily used as an efficient way
to get to food resources. They may also, as a secondary function,
help the Sugar Glider escape predators like goannas, introduced
foxes and cats, and the marsupial carnivores that foxes, cats,
and Dingos largely supplanted. The ability to glide from tree
to tree is clearly of little value with regard to the Sugar
Glider's avian predators, however, in particular owls and
kookaburras.
Although their aerial adaptation looks rather clumsy and primitive
by comparison with the highly specialised limbs of birds and
bats, Sugar Gliders can volplane for a surprisingly long distance
flights have been measured at over 50 meters (55 yd) and steer
effectively by curving one or other of the gliding membranes
(patagium). They use their hind legs to thrust powerfully
away from a tree, and when about 3 meters (3 yd) from the
destination tree trunk, bring their hind legs up close to
the body and swoop upwards to make contact with all four limbs
together.
In suitable habitats, they are common, often reaching densities
of 1 per 1,000 square meters provided that there are tree
hollows available for shelter. They live in groups of up to
7 adults, plus the current season's young, all sharing a nest
and defending their territory. Adult males mark the territory
with saliva and with scent glands, and also mark members of
the group with the scent produced by separate glands on the
forehead and chest. Visitors which lack the appropriate scent
marking are expelled violently. The dominant male mates more
frequently with the female of the group than the other males,
and does most of the scent marking. When an adult member of
the group dies, it is normally replaced: by one of the group's
own offspring if female, but by an outsider if male.
In the more temperate south, breeding starts in mid-winter
(June or July). In the north, there seems to be no particular
breeding season. Two young per female is typical; they remain
in the pouch for about 70 days, and after leaving it stay
inside the nest for another 40 or 50 days, then begin to forage
outside, usually under the care of the mother. The young are
normally ejected from the group territory at 7 to 10 months
of age. Sometimes they form new groups if an area is vacant,
but competition for territory is fierce and not many survive
the first months of independent life. In captivity, they may
live up to fifteen years.
Unlike many native animals, particularly smaller ones, Sugar
Gliders are not endangered. Despite the massive loss of natural
habitat in Australia over the last 200 years, they are adaptable
and capable of living in surprisingly small patches of remnant
bush, particularly if they do not have to cross large expanses
of clear-felled land to reach them. Several close relatives,
however, are endangered, particularly Leadbeater's Possum
and the Mahogany Glider (which, to the non-expert, looks almost
exactly like a Sugar Glider).
Like all native creatures they protected by law in Australia
where it is illegal to keep them as pets, or to capture or
sell them without a licence (which is usually only issued
for bona-fide research). However, they are not difficult to
breed in captivity under the right conditions, and small numbers
have been legally exported to America where they have formed
a breeding population for sale as pets. The Sugar Glider is
a popular pet because of its sweet, lively, inquisitive nature,
but is illegal in certain jurisdictions, such as California.
