Ailurops ursinusbear cuscus

Geographic Range

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)

Physical Description

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)

  • Average mass
    7 kg
    15.42 lb
  • Average mass
    7000 g
    246.70 oz
  • Range length
    1.2 (high) m
    3.94 (high) ft


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)

  • Range number of offspring
    1 to 2
  • Average weaning age
    8 months

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)

Communication and Perception

Food Habits

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)

  • Plant Foods
  • leaves
  • fruit
  • flowers

Ecosystem Roles

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.

Economic Importance for Humans: Positive

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

(Lee, 2000)

  • Positive Impacts
  • food

Conservation Status

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)

Other Comments

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)


Tawny Seaton (author), University of Michigan-Ann Arbor, Bret Weinstein (editor), University of Michigan-Ann Arbor.



Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females


union of egg and spermatozoan


an animal that mainly eats leaves.


A substance that provides both nutrients and energy to a living thing.


An animal that eats mainly plants or parts of plants.

internal fertilization

fertilization takes place within the female's body

island endemic

animals that live only on an island or set of islands.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate


Living on the ground.


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.


2000. "International Wildlife Magazine - About this Issue January/February 2000" (On-line). Accessed October 10, 2001 at

Colijin, E., M. Muchtar. 2000. "The Indonesian Nature Conservation Database" (On-line). Accessed September 25, 2001 at

Dwiyahreni, A., M. Kinnaird, T. O'Brien, J. Supriatna, N. Andayani. 1999. Diet and activity of the bear cuscus, *Ailurops ursinus*, in north Sulawesi, Indonesia. Journal of Mammalogy, 80 (3): 905-912.

Flannery, T., M. Archer, G. Maynes. 1987. The phylogenetic relationships of living phalangerids (Phalangeroidea: Marsupialia) with a suggested new taxonomy. Pp. 477-506 in M Archer, ed. Possums and Opossums: Studies in Evolution. Chipping Norton, N.S.W: Surrey Beatty & Sons Pty Limited in association with The Royal Zoological Society of New South Wales.

George, G. 1987. Characterisation of the living species of cuscus (Marsupialia: Phalangeridae). Pp. 507-526 in M Archer, ed. Possums and Opossums: Studies in Evolution. Chipping Norton, N.S.W: Surrey Beatty & Sons Pty Limited in association with The Royal Zoological Society of New South Wales.

Hayssen, V., A. van Tienhoven, A. van Tienhoven. 1993. Asdell's Patterns of Mammalian Reproduction. Ithaca, N.Y: Cornell University Press.

Lee, R. 2000. Back Home for Kuse. Wildlife Conservation, 103 (1): 52-55.

Myers, P. 1999. "Family: Phalangeridae" (On-line). Accessed September 26, 2001 at

National Wildlife Federation, 2000. "International Wildlife Magazine - About this issue J/F00" (On-line). Accessed September 29, 2001 at

Nowak, R. 1997. "Walker's Mammals of the World" (On-line). Accessed September 25, 2001 at

USGS, 1996. "Country Distribution Maps of Mammals on the 1996 IUCN Redlist" (On-line). Accessed September 26, 2001 at