Sun Bear

SUBFAMILY URSINAE
Ursus malayanus

APPEARANCE The sun bear has a short, sleek, black coat. The muzzle is short, and gray to faint orange in color. The crescent-shaped chest patch is yellowish or light colored. The muzzle is shorter and lighter colored than that of a black bear and in most cases the white area extends above the eyes. The ears are small and round. The paws are large and the soles are naked, which is thought to be an adaptation for climbing trees. The claws are large, curved, and pointed.

SIZE This is the smallest of the bears. Adults are about 120 to 150 centimeters (48 to 60 inches) long and weigh 27 to 65 kilograms (60 to 145 pounds). Males are 10 to 20 percent larger than females.

HABITAT Sun bears rely on tropical forest habitat. Two ecologically distinct categories of tropical forest occur. Tropical evergreen rainforest is the sun bear’s main habitat in Borneo, Sumatra, and peninsular Malaysia. This aseasonal habitat receives high annual rainfall that is relatively evenly distributed throughout the year. Tropical evergreen rainforest, inhabited by sun bears, includes a wide diversity of forest types including lowland dipterocarp, peat swamp, freshwater swamp, limestone/karst hills, hill dipterocarp, and lower montane forest.

In contrast, sun bears in mainland Southeast Asia inhabit seasonal ecosystems with a long dry season (3-7 months), during which rainfall is <100 mm per month. Seasonal forest types are usually interspersed in a mosaic that includes semi-evergreen, mixed deciduous, dry dipterocarp (<1000 m elevation), and montane evergreen forest (>1000 m). The range of sun bears overlaps that of Asiatic black bears (Ursus thibetanus) in this seasonal forest mosaic. Sun bears occur from near sea level to over 2100 m elevation, but appear to be most common in lower elevation forests.They are excellent climbers to harvest fruits . and  sometimes sleep in tree nest or on big branches.

DISTRIBUTION Sun bears occur in mainland Southeast Asia as far west as the eastern edge of India, as far north as Yunnan Province in China, and south and east to Sumatra and Borneo, respectively. Sun bears are rare at the northern and western edges of their range (southern Yunnan province, southeastern Tibet, northeast India, and Bangladesh.  Because of large-scale habitat destruction and poaching, it is likely that its range has recently been reduced in northern and western regions. Ongoing development of plantations of oil palm and rubber are reducing habitat in many areas.REPRODUCTION There is little information about reproductive behavior in the wild. Sun bears do not seem to have a defined breeding season anywhere in their range with cubs are apparently born throughout the year. The gestation period for six births at the East Berlin Zoo and two births in San Diego Zoo was reported to be 93 to 96 days, suggesting t here was no delayed implantation. Conversely, three pregnancies at the zoo in Fort Worth, Texas, lasted 174 to 240 days, suggesting delayed implantation. Litters consisted of either one or two cubs, weighing about 325 grams (10 ounces) each. Cubs are reported to remain with their mothers until they are fully grown.

SOCIAL SYSTEM Little is known about the behavior or social structure of sun bears. Except females with their offspring, sun bears usually appear to be solitary. They may congregate to feed from large fruiting trees, but this behavior appears to be rare.

DIET Sun bears are omnivores, feeding primarily on termites, ants, beetle larvae, bee larvae and honey, and a large variety of fruit species, especially figs (Ficus spp.), when available. Occasionally, growth shoots of certain palms and some species of flowers are consumed, but otherwise vegetative matter appears rare in the diet. In Bornean forests, fruits of the families Moraceae, Burseraceae and Myrtaceae make up more than 50% of the fruit diet.

Image by David Kirshner 
From Ian Stirling, ed. Bears, Majestic Creatures of the Wild.
Emmaus, Pennsylvania: Rodale Press, 1993. 240 pages.