Sun bear

The **sun bear** (*Helarctos malayanus*) is a species in the family Ursidae occurring in the tropical forests of Southeast Asia. It is the smallest bear, standing nearly 70 centimetres (28 inches) at the shoulder and weighing 25–65 kilograms (55–143 pounds). It is stockily built, with large paws, strongly curved claws, small rounded ears and a short snout. The fur is generally jet-black, but can vary from grey to red. Sun bears get their name from the characteristic orange to cream coloured chest patch. Its unique morphology—inward-turned front feet, flattened chest, powerful forelimbs with large claws—suggests adaptations for climbing.

The most arboreal (tree-living) of all bears, the sun bear is an excellent climber and sunbathes or sleeps in trees 2 to 7 metres (7 to 23 feet) above the ground. It is mainly active during the day, though nocturnality might be more common in areas frequented by humans. Sun bears tend to remain solitary but sometimes occur in pairs (such as a mother and her cub). They do not seem to hibernate, possibly because food resources are available the whole year throughout the range. Being omnivores, sun bears have a broad diet including ants, bees, beetles, honey, termites and plant material such as seeds and several kinds of fruits; vertebrates such as birds and deer are also eaten occasionally. They breed throughout the year; individuals become sexually mature at two to four years of age. Litters comprise one or two cubs that remain with their mother for around three years.

The range of the sun bear is bound by northeastern India to the north and extends south to southeast through Bangladesh, Cambodia, Myanmar, Laos, Thailand and Vietnam in mainland Asia to Brunei, Indonesia and Malaysia to the south. These bears are threatened by heavy deforestation and illegal hunting for food and the wildlife trade; they are also harmed in conflicts with humans when they enter farmlands, plantations and orchards. The global population is estimated to have declined by 35% over the past three decades. The IUCN has listed this species as vulnerable.

The sun bear is named so for its characteristic orange to cream coloured, crescent-like chest patch. The generic name *Helarctos* comes from two Greek words: ήλιος (*hēlios*, 'related to the sun') and αρκτος (*arctos*, 'bear'). Another name is 'honey bear' (*beruang madu* in Malay and Indonesian), in reference to its habit of feeding on honey from honeycombs. 'Honey bear' can also refer to the kinkajou.

The sun bear was first described in 1821 from Sumatra by British statesman Sir Thomas Stamford Bingley Raffles, who gave it the scientific name *Ursus malayanus*. In 1825, American naturalist Thomas Horsfield placed the species in a genus of its own, *Helarctos*. Two subspecies have been proposed on the basis of variations in size:

* Malayan sun bear (*H. m. malayanus*) Raffles, 1821: Occurs on the Asian mainland and Sumatra.
* Bornean sun bear (*H. m. euryspilus*) Horsfield, 1825: Occurs only in Borneo. Its skull is smaller than that of the Malayan sun bear.

*H. anmamiticus*, described by Pierre Marie Heude in 1901 from Annam, is not considered a distinct species, but is subordinated (a junior synonym) to *H. m. malayanus*. In 1906, Richard Lydekker proposed another subspecies by the name *H. m. wardii* for a sun bear skull, noting its similarities to a skull from Tibet with a thicker coat; however the Tibetan specimen was later found to be an Asian black bear (*Ursus thibetanus*). Genetic differences between the two subspecies are obscure. In 2002, Christopher Fitzgerald and Paul Krausman (of the American Society of Mammalogists) considered the sun bear monotypic.

The phylogenetic relationships among ursid species have remained ambiguous over the years. Noting the production of fertile hybrids between sun bears and sloth bears (*Melursus ursinus*), it was proposed that *Helarctos* be treated as a synonym of *Melursus*. However, studies differed on whether the two species were closely related. A 2007 phylogenetic study gives the relationships of the sun bear with other species of Ursidae based on complete mitochondrial DNA sequences as shown in the cladogram below. The brown bear/polar bear lineage was estimated to have diverged from the two black bears/sun bear lineage around 5.54 to 6.72 million years ago; the sun bear appears to have diverged from the two black bears 5.09–6.26 mya.However, the phylogenetic tree constructed by a nuclear gene sequencing analysis in 2008 swapped the positions of the sun bear and the sloth bear obtained in the previous study; moreover, all relationships other these two positions were well resolved. The researchers noted the need for further study to fully resolve the relationship.