The sugar glider (Petaurus breviceps)
The sugar glider (Petaurus breviceps) is a small, omnivorous, arboreal, and nocturnal gliding possum. The common name refers to its predilection for sugary foods such as sap and nectar and its ability to glide through the air, much like a flying squirrel. They have very similar habits and appearance to the flying squirrel, despite not being closely related—an example of convergent evolution. The scientific name, Petaurus breviceps, translates from Latin as "short-headed rope-dancer", a reference to their canopy acrobatics.
Appearance
Petaurus breviceps is a species of diprotodontid mammal of the family Petauridae. They are nocturnal and arboreal animals. Petaurus breviceps is a small animal measuring 15-20 cm and weighing 95-170 g, resembling a squirrel in body shape. The long, fluffy tail of Petaurus breviceps is able to curl up and can hang from it or be used as a rudder in flight. The snout of Petaurus breviceps is short and slightly pointed, the ears are large and very mobile, and the eyes are large and black. The fur of Petaurus breviceps is thick and soft, and it has five toes on each foot and scent glands on the forehead, chest and near the anus, which it uses to mark its territory.
Lifestyle and nutrition
These animals live in forests, plantations and orchards, and are nocturnal. They feed on the sweet sap of acacia and some types of eucalyptus, plant nectar and pollen, and small vertebrates and invertebrates. A distinctive feature of Petaurus breviceps is the thin leathery membrane extending from the fifth toe of the front legs to the first toe of the hind legs. They are invisible when the animal is resting, but extend during flight: gliding from tree to tree, Petaurus breviceps can travel up to 50 metres.
Torpor
Sugar gliders can tolerate ambient air temperatures of up to 40 °C (104 °F) through behavioural strategies such as licking their coat and exposing the wet area, as well as drinking small quantities of water. In cold weather, sugar gliders will huddle together to avoid heat loss, and will enter torpor to conserve energy. Huddling as an energy conserving mechanism is not as efficient as torpor. Before entering torpor, a sugar glider will reduce activity and body temperature normally in order to lower energy expenditure and avoid torpor. With energetic constraints, the sugar glider will enter into daily torpor for 2-23 hours while in rest phase. Torpor differs from hibernation in that torpor is usually a short-term daily cycle. Entering torpor saves energy for the animal by allowing its body temperature to fall to a minimum of 10.4 °C (50.7 °F) to 19.6 °C (67.3 °F). When food is scarce, as in winter, heat production is lowered in order to reduce energy expenditure. With low energy and heat production, it is important for the sugar glider to peak its body mass by fat content in the autumn (May/June) in order to survive the following cold season. In the wild, sugar gliders enter into daily torpor more often than sugar gliders in captivity. The use of torpor is most frequent during winter, likely in response to low ambient temperature, rainfall, and seasonal fluctuation in food sources.
Reproduction
Petaurus breviceps usually have two young. They spend about 70 days in the pouch and then remain in the nest for another 40-50 days, after which they begin foraging for food under the care of their mother. Unlike many marsupials, Petaurus breviceps does not appear to be endangered and this charming little beast has recently become a very popular pet.
Conservation
Under the prior taxonomy, the sugar glider was not considered endangered, and its conservation rank was "Least Concern (LC)" on the IUCN Red List. However, with newer taxonomic studies indicating that it has a small and restricted range, it is now thought to be far more sensitive to potential threats. For example, the species' native range was hit hard by the 2019-20 Australian bushfires, which occurred just a few months prior to the publishing of the study indicating the true extent of its range. Sugar gliders use tree hollows, making them especially sensitive to intense fires. However, despite the loss of natural habitat in Australia over the last 200 years, it is adaptable and capable of living in small patches of remnant bush, particularly if it does not have to cross large expanses of cleared land to reach them. Sugar gliders may persist in areas that have undergone mild-moderate selective logging, as long as three to five hollow bearing trees are retained per hectare. Although not currently threatened by habitat loss, the ability of sugar gliders to forage and avoid predators successfully may be decreased in areas of high light pollution.
In captivity
In captivity, the sugar glider can suffer from calcium deficiencies if not fed an adequate diet. A lack of calcium in the diet causes the body to leach calcium from the bones, with the hind legs first to show noticeable dysfunction. Calcium to phosphorus ratios should be 2:1 to prevent hypocalcemia, sometimes known as hind leg paralysis (HLP). Their diet should be 50% insects (gut-loaded) or other sources of protein, 25% fruit and 25% vegetables. Some of the more recognised diets are Bourbon's Modified Leadbeaters (BML), High Protein Wombaroo (HPW) and various calcium rich diets with Leadbeaters Mixture (LBM). Iron storage disease (hemochromatosis) is another dietary problem that has been reported in captive gliders and can lead to fatal complications if not diagnosed and treated early.
A large amount of attention and environmental enrichment may be required for the highly social species, especially for those kept as individuals. Inadequate social interaction can lead to depression and behavioural disorders such as loss of appetite, irritability and self-mutilation.
As a pet
In several countries, the sugar glider (or what was formerly considered to be the sugar glider) is popular as an exotic pet, and is sometimes referred to as a pocket pet. In Australia, there is opposition to keeping native animals as pets from Australia's largest wildlife rehabilitation organisation (WIRES), and concerns from Australian wildlife conservation organisations regarding animal welfare risks including neglect, cruelty and abandonment.
In Australia, sugar gliders can be kept in Victoria, South Australia, and the Northern Territory. However, they are not allowed to be kept as pets in Western Australia, New South Wales, the Australian Capital Territory, Queensland or Tasmania.
DNA analysis indicates that "the USA (sugar) glider population originates from West Papua, Indonesia with no illegal harvesting from other native areas such as Papua New Guinea or Australia". Given that the West Papuan gliders have been tentatively classified as Krefft's gliders (albeit to be changed in the future), this indicates that at least the captive gliders kept in the United States are Krefft's gliders, not sugar gliders.
