Ailurops ursinus
bear cuscus

Ailurops ursinus is found only on Sulawesi and the Talaut Islands of Indonesia.

(George, 1987; USGS, 1996)

Ailurops ursinus is an arboreal marsupial that lives in the upper canopy of lowland tropical rainforests.

(Dwiyahreni et al, 1999; Lee, 2000)

Ailurops ursinus has a short face and short, furry ears. The pelage is composed of a fine, wiry underfur and coarse guard hairs. Coloration ranges from black to grey to brown with a lighter colored belly and tips of extremities, with variation depending on geographic location and age of the animal.

The prehensile, unfurred tail is half of the total body length and is used in conjunction with the forefeet (which have two opposable digits) and syndactylous hindfeet to move between trees. Ailurops ursinus is the most primitive of all phalangerids, retaining primitive dentition and cranial features.

(George, 1987; Nowak, 1997; Myers, 1999; National Wildlife Federation, 2000)

Mating system and behavior is unknown.

(Hayssen et al, 1993)

An adult female A. ursinus gives birth one or two times a year.

(Lee, 2000)

Young are born at an extrememly altricial stage and continue development in the mother's pouch. After eight months, development is sufficient to allow survival, although the young remains with the mother for an additional period. It is unknown at what age Ailurops ursinus reaches developmental maturity.

(Lee, 2000)

Ailurops ursinus tends to live in pairs or groups of three to four. They are arboreal, moving slowly from tree to tree using their prehensile tail and grasping forefeet. A great proportion of the day is spent resting or sleeping, with little time devoted to feeding and grooming and even less to social interactions. It has been hypothesized that activity is spread throughout the day and night, with periods of rest between feeding or other activity. Leaves, the main food source, contain low nutrient levels and the resting periods may be necessary to digest the cellulose.

(Dwiyahreni et al, 1999; Lee, 2000)

Ailurops urisinus eats the leaves of many different tree species, but three make up half of the total diet. Young leaves are much preferred, probably because they are easier to digest and contain fewer toxins. However, the bear cuscus prefers mature leaves of mistletoes, which have more protein than the young leaves. A small amount of flowers and unripe fruit (which contains more protein than ripe fruit) are also eaten.

Common foods eaten include: tree leaves (Garuga floribunda, Melia azedarach, Dracontomelum dao), mistletoe leaves (Cananga odorata, Palaquium amboinense), unripe fruit, flowers and buds.

(Dwiyahreni et al, 1999; Lee, 2000)

Although primarily a folivore, Ailurops ursinus also consumes unripe fruit, flowers and buds. These have not yet completed the development necessary in order to be able to give rise to another plant. Thus, the bear cuscus tends to restrict the reproductive potential of some plants.

Although not much sought-after, the meat of A. ursinus is still commonly found in the restaurants and markets of Indonesia.

(Lee, 2000)

Under the name Phalanger ursinus, A. ursinus has protected status in Indonesia. Hunting greatly threatens this animal because of its low reproductive rate, particularly because females with young in the pouch may be killed and the young then abandoned, almost certainly dying.

(The Indonesian Nature Conservation Database, 2000; National Wildlife Federation, 2000; Lee, 2000)

Ailurops ursinus is the most primitive and plesiomorphic of all phalangerids, and is thus placed in a separate subfamily, Ailuropinae. It is hypothesized that A. ursinus was isolated on the island of Sulawesi when the island first emerged in the Miocene, accounting for the animal's morphological divergence from the rest of the family Phalangeridae.

(Flannery et al, 1987; George, 1987)