POSSUMS AND CUSCUSES: Phalangeridae

PHYSICAL CHARACTERISTICS

The Phalangeridae family, or phalangers (fah-LAN-jerz), are made up of five groups of species. Three of these groups are cuscuses and two are possums. Phalangers are small- to medium-sized marsupial mammals. Like all marsupial mammals, the females give birth to tiny, underdeveloped young that finish their development in their mother's pouch.

Possums and cuscuses range in size from 24 to 47 inches (60 to 120 centimeters) long, including the tail, and weigh from 2 to 22 pounds (1 to 10 kilograms). The smallest member of this family is the small Sulawesi cuscus, and the largest is the Sulawesi bear cuscus. Both live in Indonesia.

Members of this family have soft, dense fur that hides small ears. Most species are a solid brown or gray, but the Woodlark cuscus and the black spotted cuscus are spectacularly patterned. Many other species have a dark stripe that runs down the top of their back.

All cuscuses and possums are good climbers. Their feet are adapted to life in the trees. Their hind feet have five toes. The first toe (called the hallux, HAL-lux) has no claw, and is opposed to the other four. This means that this toe, like the thumb on a human hand, can reach across and touch the tip of the other toes (unlike, for example, a dog paw or human foot, where none of the toes can bend to touch each other). The first two toes on the front feet are also opposable. This adaptation makes it easier to grip branches when climbing. Possums and cuscuses also have a prehensile, or flexible grasping, tail that they can wrap around branches to help steady themselves. Usually the tail has no fur on it to improve its grip.

GEOGRAPHIC RANGE

Phalangers are found in New Guinea, Australia, Tasmania, the Indonesian island of Sulawesi, and a few other small islands. The common brush-tailed possum was introduced in New Zealand over a century ago and has become an alien (non-native) pest species.

HABITAT

Possums and cuscuses spend their lives in trees. Most live in rainforests. However, the common brush-tailed possum has adapted to life in developed areas. It is often found in suburban gardens and city parks. Sometimes it becomes a pest when it makes its home in buildings by finding openings in the roofline and nesting between the house ceiling and the roof.

DIET

Possums and cuscuses are herbivores, eating almost exclusively plants. Some eat mainly leaves, while others eat mainly fruit. The common brush-tailed possum eats a wider variety of foods than most members of this family, adapting its diet to what is abundant in any given area.

BEHAVIOR AND REPRODUCTION

Most members of this family are nocturnal, or active at night, but the black-spotted cuscus and the Sulawesi bear cuscus feed during the day. All species are arboreal (tree-dwelling) except for the ground cuscus—but even though this animal lives in burrows underground, it is a good climber, and climbs trees to feed on fruit.

ENDANGERED STAMPS

The common spotted cuscus was selected to be one of twelve endangered species featured on a 2001 United Nations 34 cent stamp. Every year since 1993, the United Nations has released a new series of stamps in an effort to bring attention to endangered species and to CITES (the Convention on International Trade in Endangered Species), an agreement among nations to help preserve species by controlling their exportation and importation (http://www.cites.org).

Little is known about the social behavior of members of this family. Most species appear to live alone, although a few may form pairs. Males are aggressive toward each other when their home range overlaps. Females usually produce two litters consisting of one offspring each year. Like all marsupials, the young are tiny, undeveloped creatures that finish maturing while attached to a teat, or nipple, in the mother's forward-facing pouch. After five to eight months, the young leave the pouch and are carried on their mother's back for a few more weeks or months.

POSSUMS, CUSCUSES, AND PEOPLE

Cuscuses are hunted for meat and sometimes fur in New Guinea. Some species, such as the common spotted cuscus, are also sold as pets. Cuscuses play a role in religious beliefs in some parts of Indonesia, and in these areas, they are not eaten. The common brush-tailed possum is considered a pest in many areas. The Telefomin cuscus was not discovered until the late 1980s, and so it is of special interest to scientists.

CONSERVATION STATUS

Two species in this family are considered Endangered and at risk of going extinct in the wild. These are the black-spotted cuscus and the Telefomin cuscus. The population of black-spotted cuscuses is declining because of habitat loss and continued hunting. Little is known about the Telefomin cuscus. Two other species are considered Vulnerable, facing a high risk of extinction, and half a dozen others are of concern to conservationists, but too little is known about them to make an accurate population evaluation.

GROUND CUSCUS (Phalanger gymnotis): SPECIES ACCOUNTS

Physical characteristics: The ground cuscus has fur that is light to dark gray with a stripe down its back.

Geographic range: This cuscus is found in New Guinea and the Aru Islands.

Habitat: This animal lives in the rainforest from sea level to 8,900 feet (2,700 meters).

Diet: The ground cuscus eats mostly fruit, but will also eat leaves and sometimes insects and small vertebrates (animals with a backbone).

Behavior and reproduction: This is the only cuscus that sleeps in underground burrows and moves along the rainforest floor. Its burrows are usually under trees, along streams, or in caves. The ground cuscus is active at night and searches for food on the ground and in trees. The young leave their mother's pouch five to seven months after birth.

Ground cuscuses and people: These cuscuses are hunted throughout New Guinea, and are important figures in local folklore in some areas.

Conservation status: The ground cuscus is common in many parts of New Guinea, and is probably not threatened. ∎

COMMON BRUSH-TAILED POSSUM (Trichosurus vulpecula): SPECIES ACCOUNTS

Physical characteristics: The common brush-tailed possum varies widely in size and color. Its fur can be black, gray, reddish, or brown. In the colder parts of its range, individuals tend to be larger and furrier than those who live in warmer regions. Unlike some members of this family, the common brush-tailed has a patch of bushy fur on its tail.

Geographic range: Brush-tailed possums live in eastern and southwestern Australia and in New Zealand.

Habitat: The brush-tailed possum is adaptable, living in cool, damp forests and dry regions with few trees. It has adjusted successfully to life in city parks and the suburbs.

Diet: Common brush-tailed possums are herbivores, eating leaves, buds, flowers, and fruits, garden plants, herbs, and grasses.

Behavior and reproduction: Common brush-tailed possums are active at night and normally live alone. However, if there are many possums and few places to shelter, they may share their sleeping space with another possum. Male common brush-tailed possums try to avoid conflict with other males, although they can be aggressive in defending their home range. They are known for their loud grunts, growls, and screeches that are used to warn away other males during breeding season. Females usually have one offspring each year, born after an eighteen-day pregnancy. The young then live in the mother's pouch for about seven months.

Common brush-tailed possums and people: This animal probably has more contact with people than any other Australian marsupial because it has adapted so well to cities and suburban areas. It is trapped for its fur and is considered a pest in some farming areas and in New Zealand, where it was introduced about 150 years ago.

Conservation status: The common brush-tailed possum is common within its range and is not threatened with extinction. ∎

FOR MORE INFORMATION

Books:

Finney, Tim F. Mammals of New Guinea, 2nd ed. Ithaca, NY: Cornell University Press, 1995.

Menkhorst, Frank. A Field Guide to the Mammals of Australia, 2nd ed. Oxford, U.K.: Oxford University Press, 2001.

Nowak, Ronald. M. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press, 1995.

Web sites:

Marsupial Society of Australia. http://www.marsupialsociety.org (accessed May 9, 2004).

Parks and Wildlife Service Tasmania. "Brushtail Possum." http://www.parks.tas.gov.au/wildlife/mammals/btposs.html (accessed on June 30, 2004).

Queensland Government Environmental Protection Agency/Queensland Parks and Wildlife Service. "Nature Conservation." http://www.epa.qld.gov.au/nature_conservation (accessed on June 30, 2004).