Phalangers are a small group of arboreal mammals belonging to the family Phalangeridae, of which 20 species are recognized in six genera. Phalangers, more commonly known as possums and cuscuses, are marsupials but with a vague resemblance to some monkeys. Indeed many early European explorers thought that they were monkeys. These species occur in Australia, New Guinea and adjacent islands west to Sulawesi (Indonesia) and east to the Solomon Islands. New Guinea is thought to be the main center for evolution of these species with eight species represented. In addition to their natural range, some species have been introduced, such as the brushtail possum (Trichosurus vulpecula) to New Zealand (for their valuable fur) and the common cuscus (Phalanger orientalis) to the Solomon Islands.
Phalangers are short, compact animals with thickly furred bodies. A wide range of colors occur from the predominantly reddish brown fur of the common cuscus to the pure white coat with dark spots of the spotted cuscus (Spilocuscus maculatus) and the strikingly marked black spotted cuscus (S. rufoniger), the largest of all phalangers with a black back, orange-russet limbs, white underside and russet and white head. In most species the short ears are concealed by the thick fur. Their limbs are adapted to climbing, with sharp, curved claws for climbing and clawless, but opposable, first hind toes which assist with grasping small branches. They also have a strong prehensile tail, which is usually bare towards the tip. Phalangers are most active at night—their large, forward-pointing eyes enable them to receive sufficient light to guide them through the tangle of branches and leaves in the forest canopy. A wide range of food items are taken, including young leaves, buds, shoots, fruit and occasionally insects, birds eggs, and small lizards.
Little is known about the social behavior of many of these species. Phalangers are probably capable of breeding throughout the year, but apart from when females are receptive to breeding, they all appear to be solitary animals, occupying a range of 7.5-20 acres (3-8 ha), depending on food, shelter and population density. In the wild, phalangers are relatively long-lived animals, with some living up to 13 years of age.
Possums and cuscuses are well-known to hu mans—possums, in particular, for the economic damage they cause in timber plantations, as well as for their crop-raiding habits. In New Zealand, the damage caused to native vegetation has also been significant, as most of these trees evolved in the absence of foliage-feeding animals and are therefore unable to produce enough toxins to repel attack. It is also thought that the common brushtail may spread tuberculosis, which has led to a major eradication scheme of this species in New Zealand.
As they rarely come down to the ground, possums and cuscuses have few natural predators, apart from large birds of prey and snakes. Human activities are thought to have had a major impact, at least on certain species, through habitat destruction which, in certain cases, is made worse by hunting pressure. Although the precise conservation status of most species is still uncertain, at least one species, the Woodlark Island cuscus (Phalanger lullulae) which is confined to Woodlark Island and Alcester Island in Papua New Guinea is known to be in serious trouble. A species of lowland rainforest cuscus, it is only known from eight specimens—four collected in 1894 and another four from 1953. Almost nothing is known about the ecology of this cuscus, which is now thought to be threatened as a result of deforestation and overhunting within its restricted range. Another species about which very little is known is the scaly-tailed possum (Wyulda squamicaudata)—the only species in its genus—known from northwestern Australia. In New Guinea, most species of cuscus are hunted for their meat and prized fur which is worn at special ceremonies. It is essential that appropriate conservation measures are taken to protect the native habitat of all of these species and to fully evaluate the extent of threats facing them from habitat loss and hunting.