This species is distributed from the islands of Timor (Indonesia and Timor Leste), Wetar and Leti (both to Indonesia) through the Kai Islands and a number of the Moluccan Islands of Indonesia (including: Ambon, Buru, and Seram); it is present on the islands of Misool, Waigeo, Batanta, and Salawati (all Indonesia), and ranges over much of the northern part of the island of New Guinea (Indonesia and Papua New Guinea), including a number of offshore islands. It ranges as far east as the Bismarck Archipelago, Papua New Guinea, where it is present on many islands including the islands of New Britain and New Ireland. It also occurs on many of the Solomon Islands.

Many of the insular island populations are the result of prehistorical introductions, possibly including: Timor, Seram, Buru, Sanana, the Kai Islands, the Bismarck Archipelago, and the Solomon Island chain.

Phalanger orientalis is thought to have originated on New Guinea and then to have been distributed primarily by prehistoric humans to the range it currently occupies (Nowak, 1999). That range now includes the South West Pacific islands of Buru, Seram, the Solomon and Molucca Islands, northern New Guinea, and the Bismark Archipelago (Nowak, 1999) . Until recently, P. orientalis and P. intercastellanus (Southern Common Cuscus) were thought to belong to the same species (Flannery, 1995). P. intercastellanus inhabits northern Australia, the Aru Islands, and the Louisade Archipelago (Strahan, 1995).

Biogeographic Regions: australian (Native ); oceanic islands (Introduced , Native )

P. orientalis, like others in the family Phalangeridae, is heavy and powerfully built (Nowak, 1999). The average mass is about 2.1 kg. This is slightly lower in females (Grizmek, 1990).

The tail is prehensile naked at the end. It is covered with horny papillae. The tail length varies from 28 to 42 cm (Grizmek, 1990). The male tail is completely white but female tails are white only on the tips.

In adult males, the thick, wooly fur ranges in color from white to medium or dark grey (Nowak, 1999). In adult females, the color ranges from reddish-brown to brownish-grey. The stomach area is commonly white. The male has a distinct yellowish chest gland. Usually a dark stripe runs from the head to the lower back. The young of this species are reddish-brown. (Flannery, 1995; Nowak, 1999)

The digits are of different lengths and are tipped by long, curved claws. Their paws are syndactylous, with the first and second digits opposable to the rest. The soles of their feet are naked and striated. The female pouch has four mammae (Nowak, 1999). The facial features include large eyes, long canines and a snout longer than that of Spilocuscus maculatus (Spotted Cuscus). The teeth are simple, low crowned and used for grinding (Flannery, 1995).

Range mass: 1.0 to 5.0 kg.

Average mass: 2.1 kg.

Range length: 35 to 55 cm.

Average length: 39 cm.

Other Physical Features: endothermic ; bilateral symmetry

Habitat and Ecology

Systems

• Terrestrial

P. orientalis is resitricted to tropical rainforests and thick scrub in the South West Pacific (Nowak, 1999). They have also been spotted in gardens, probably due to the high abundance of edible plants (Flannery, 1995).

Range elevation: 0 to 1600 m.

Habitat Regions: tropical

Terrestrial Biomes: rainforest

P. orientalis climbs slowly through the rainforests and locates mainly leaves, tree seeds, fruit, buds and flowers on which they feed (Girzmek, 1990). It has been spotted eating the green fruit of the Red Cedar (Toona australis) and the buds and flowers of Corky Bark (Carallia brachiata). A paste derived from the seeds of the Black Bean Tree (Castanospermum australe) was found in the stomach of one animal. While in captivity it primarily eats leaves and fruit (Flannery, 1995).

Primary Diet: herbivore (Folivore , Frugivore )

P. orientalis does not have any recorded ecological roles.

P. orientalis had not been closely studied due to its secluded lifestyle. The following are a few specific predators that have been documented: White-bellied Sea-Eagle (Haliaeetus leucogaster) (Heinsohn, 2000), Amethystine (Morelia amethistina)(Flannery, 1995), Carpet Pythons (Morelia s. cheynei)(Flannery, 1995), and possibly Dasyurids (Grizmek, 1990). The assumption is that these and other species like them prey upon P. orientalis.

Known Predators:

• white-bellied sea-eagles (Haliaeetus leucogaster)
• amethystine pythons (Morelia amethistina)
• carpet pythons (Morelia spilota)
• dasyurids (Dasyuridae)

Phalanger orientalis is prey of:
Haliaeetus leucogaster
Morelia amethistina
Morelia spilota

This list may not be complete but is based on published studies.

Observations: Little is known about the longevity of these animals. One captive animal lived 4.1 years (Richard Weigl 2005), but further studies are necessary before the maximum longevity of these animals can be correctly estimated.

The gestation period for P. orientalis lasts around 13 days. Normally the females births twins, but the number of young ranges from one to three (Grizmek, 1990). Usually, one of the twins dies before weaning (Nowak, 1999). The weight at birth is less than 1 gram (Grizmek, 1990).

Normally, the reproductive cycle occurs only once a year. Mating and reproductive seasons are from June through October, though March and November births have been observed (Tyndale-Brisco, 1987).

Because P. orientalis has not been well studied, information on the reproctive behavior is sparse.

Breeding season: June through October

Range number of offspring: 1 to 3.

Average gestation period: 13 days.

Range weaning age: not known (high) days.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous

Average number of offspring: 2.

Parental Investment: altricial ; female parental care

CITES: appendix ii

IUCN Red List of Threatened Species: least concern

Population

Population Trend

Major Threats

Conservation Actions

In New Guinea, P. orientalis is hunted for food by native tribes, though this is rare (Flannery, 1995).

Positive Impacts: food