Feather-tailed possums

(Acrobatidae)

Class Mammalia

Order Diprotodontia

Family Acrobatidae

Thumbnail description
Small possums with a very long feather-like tail, fringed on two sides with straight hairs; the body fur is predominantly pale gray, white on the underside, with white and dark face and body markings that vary with species

Size
Head and body length 2.4–4.7 in (6–12 cm); tail 2.6–6 in (6.5–15 cm); weight 0.35–2.1 oz (10–60 g)

Number of genera, species
2 genera; 2 species

Habitat
Forests, woodland, scrub, and gardens

Conservation status
Not threatened

Distribution
Eastern Australia and New Guinea

Evolution and systematics

This small family of just two living species has created more than its share of taxonomic debate. Feather-tailed possums were once thought to be true possums of the family Phalangeridae. In the 1970s, they were moved to the pygmy possum family, Burramyidae. Soon after that, they were given full family status of their own and became the Acrobatidae, allied first to the pygmy possums in the superfamily Burramyoidea, then with gliding possums in the Petauroidea. In 1987, the family was repositioned again, this time alongside the honey possum in the superfamily Tarsipedoidea.

Acrobatids differ from other possums in having six pads on their feet instead of five (an adaptation to enhance grip when climbing) and a tail with rows of long stiff hairs along each side, forming a feather-like structure. Undoubtedly, this is an adaptation to gliding. In the Australian pygmy glider (Acrobates pygmaeus), the tail is used as a rudder to give the animal increased control as it glides though the air on membranes of skin stretched between its front and back legs. But the other species, New Guinea's feather-tailed possum (Distoechurus pennatus), does not have such a membrane and cannot glide.

The featherlike tail is a relic that shows that this species has abandoned the gliding lifestyle its ancestors spent several million years evolving.

Physical characteristics

Feather-tailed possums possess a variety of adaptations to life in the trees, as well as a number of physical characteristics that set them well apart from other possums. Acrobates is

tiny—the smallest gliding marsupial, weighing less than 0.5 oz (14 g). The gliding membrane is a narrow strip of furry skin. The fingers and toes end in expanded round pads with minutely serrated surfaces and sharp claws, thus ensuring good grip on rough and smooth surfaces alike. Distoechurus is longer and three to four times heavier than its gliding cousin and its fingers and toes lack expanded tips. Its face bears distinctive markings in the form of black and white stripes. Both species have large eyes and rounded, sparsely haired ears with complex fleshy nodules at the opening to the ear canal.

Distribution

Both species of feather-tailed possum are doubtless descended from a common ancestor that lived throughout what is now eastern Australia and New Guinea before rising sea levels flooded the Torres Straits. Distoechurus is endemic to New Guinea and Acrobates is found from the extreme northeastern tip of Australia at Cape York all the way down to southernmost Victoria and South Australia. It does not occur on Tasmania.

Habitat

Acrobatids are strictly arboreal. Individuals rarely, if ever, venture to ground level, where they would be vulnerable to predators, including other mammals and reptiles. The pygmy glider lives in a diverse range of forest habitat from tropical rainforest of northern Queensland to the montane eucalyptus woodlands of the south.

Behavior

Feather-tailed possums are nocturnal, shy, and elusive. They live in tall trees, often in remote forests, and Acrobates has the ability to swoop from one tree to another. All this makes close observation extremely difficult; many details of their everyday lives remain unknown. Even pygmy gliders kept in captivity have proved tricky subjects for study—gliders kept in sparse enclosures or in pairs rather than groups do not survive well or breed. Acrobates is highly social. In the wild, groups of up to 20 or more animals of both sexes and various ages may build and share a series of nests within a joint home range. Aggression is apparently rare, and animals of all ages rest huddled close together, especially during periods of cold weather or food shortage when they enter a deep torpid sleep. In contrast, Distoechurus spends more time alone or in pairs. Being relatively large, it is less dependent on shared body heat to conserve energy.

Both species of acrobatid possum are superb climbers, but only Acrobates has retained the ability to glide. A glide is an extended leap, during which the animal splays its four limbs to open a narrow web of furry skin called the "patagium." This serves as a parachute, slowing the rate of descent and giving the possum some control over its trajectory and allowing it to travel 65 ft (20 m) or more through the air. Just before landing, the possum swings its hind feet forward, thus reducing airspeed, and bracing all four legs for landing on a vertical surface such as a tree trunk. The featherlike tail is used as a rudder and a brake to help control the short "flight."

Feeding ecology and diet

Feather-tailed possums specialize in high-energy, high-protein foods such as nectar, flowers, and insects. Most feeding occurs at night, although nursing mothers are sometimes forced to forage during the day to meet their family's demands for milk.

Reproductive biology

Breeding can happen at any time of year in the tropics, but births in both species have a seasonal peak in spring. Female pygmy gliders breed in their first year and may share a nest with other adults, including other breeding females. A postpartum estrus and embryonic diapause mean that a second litter may be born within a day or two of the first litter being weaned. Very little is known about the reproductive biology of Distoechurus. Both species might be polygynous.

Conservation status

Both Distoechurus and Acrobates are thought to be common in suitable habitat, though detailed population information is strictly limited.

Significance to humans

None known.

Species accounts

List of Species

Feather-tailed possum

Distoechurus pennatus

taxonomy

Distoechurus pennatus (Peters, 1874), Irian Jaya, Indonesia.

other common names

French: Possum plumée de Nouvelle Guinée; German: Federschwanzbeutler; Spanish: Opósum de cola plumose.

physical characteristics

Head and body length 4–5 in (10–13 cm), tail 5–6 in (12–15 cm) long; fur mainly gray, with black and white facial stripes. No gliding membrane.

distribution

New Guinea.

habitat

Disturbed and secondary forest, rainforest, scrubland, and gardens.

behavior

Nocturnal, arboreal, solitary most of the year.

feeding ecology and diet

Flowers, fruit, and insects.

reproductive biology

Probably polygynous. One or two young born in spring.

conservation status

Not threatened; apparently abundant.

significance to humans

None known.

Pygmy glider

Acrobates pygmaeus

taxonomy

Acrobates pygmaeus (Shaw, 1793), Sydney, Australia.

other common names

English: Feathertail glider, pygmy gliding possum, pygmy phalanger, flying mouse; French: L'acrobat pygmée; German: Zwerggleitbeutler; Spanish: Acróbata pigmeo.

physical characteristics

Head and body length 2.5–3 in (6.5–8 cm); tail 2.5–3 in (6.5–8 cm) long; soft gray fur, white on underside, dark eyerings and variable body markings; loose skin along flanks forms gliding membrane when limbs are spread wide.

distribution

Eastern Australia.

habitat

Eucalyptus forest and woodland.

behavior

Nocturnal, arboreal, highly social, glides between trees.

feeding ecology and diet

Insects and nectar.

reproductive biology

Probably polygynous. Litters of three to four young born at any time of year; spend 65 days in the pouch, then suckled in the nest for another month.

conservation status

Not threatened, and presumed secure.

significance to humans

None known.

Resources

Books

Flannery, T. Mammals of New Guinea. Carina, Australia: Robert Brown and Associates, 1990.

Morris, P., and A.-J. Beer. World of Animals: Mammals. Vol 10, Marsupials. Danbury, CT: Grolier, 2002.

Nowak, R. "Feather-tailed Possums (Diprotodontia; Family Acrobatidae)." In Walker's Mammals of the World. Vol I, 6th edition. Baltimore and London: Johns Hopkins University Press, 1999.

Strahan, R. The Mammals of Australia, Revised Edition. Sydney: New Holland, 1998.

Amy-Jane Beer, PhD