The sloth bear (Melursus ursinus), also known as the Indian bear, is a myrmecophagous bear species native to the Indian subcontinent. It feeds on fruits, ants and termites. It is listed as vulnerable on the IUCN Red List, mainly because of habitat loss and degradation. It is the only species in the genus Melursus.
It has also been called "labiated bear" because of its long lower lip and palate used for sucking up insects. It has long, shaggy fur, a mane around the face, and long, sickle-shaped claws. It is lankier than brown and Asian black bears. It shares features of insectivorous mammals and evolved during the Pleistocene from the ancestral ursine bear through divergent evolution.
Sloth bears breed during spring and early summer and give birth near the beginning of winter. When their territories are encroached upon by humans, they sometimes attack them. Historically, humans have drastically reduced these bears' habitat and diminished their population by hunting them for food and products such as their bacula and claws. Sloth bears have been tamed and used as performing animals and as pets.Servheen
Taxonomy George Shaw in 1791 named the species Bradypus ursinus. In 1793, Meyer named it Melursus lybius, and in 1817, de Blainville named it Ursus labiatus because of its long lips. Illiger named it Prochilus hirsutus, the Greek genus name indicating long lips, while the specific name noted its long and coarse hair. Fischer called it Chondrorhynchus hirsutus, while Tiedemann named it Ursus longirostris.
Subspecies and range Name Description Distribution Indian sloth bear (M. u. ursinus) (Shaw, 1791) This is the nominate subspecies and has a large skull with a condylobasal length of about in females and about in males. The sloth bear is the most widespread bear species in India, where it mostly occurs in areas with forest cover, low hills bordering the outer range of the Himalayas from Punjab to Arunachal Pradesh. It is absent in the high mountains of Himachal Pradesh and Jammu and Kashmir, the northwestern deserts of Rajasthan, and a broad unforested swath in the south, where Mount Abu Wildlife Sanctuary is located. Sloth bear occurs in protected areas such as Shoolpaneshwar, Ratanmahal, Jessore,Servheen, pp. 225–240 and Balaram Ambaji Sanctuaries. In Nepal, it is restricted to the Terai. Sri Lankan sloth bear (M. u. inornatus) Pucheran, 1855 The Sri Lankan sloth bear is smaller than the nominate subspecies, has a smaller skull with a condylobasal length of about in females and about in males. It has much shorter body hair, and sometimes lacks the characteristic white chest mark. At the turn of the century, the Sri Lankan sloth bear occurred throughout Sri Lanka. But due to wide-scale conversion of upland forests into tea and coffee plantations, it is now restricted to the northern and eastern lowlands.
Evolution Sloth bears may have reached their current form in the Early Pleistocene, the time when the bear family specialised and dispersed. A fragment of fossilised humerus from the Pleistocene, found in Andhra Pradesh's Kurnool Basin is identical to the humerus of a modern sloth bear. The fossilised skulls of a bear once named Melursus theobaldi found in the Shivaliks from the Early Pleistocene or Early Pliocene are thought by certain authors to represent an intermediate stage between sloth bears and ancestral brown bears. M. theobaldi itself had teeth intermediate in size between sloth bears and other bear species, though its palate was the same size as the former species, leading to the theory that it is the sloth bear's direct ancestor. Sloth bears probably arose during the Middle Pliocene and evolved in the Indian subcontinent. The sloth bear shows evidence of having undergone a convergent evolution similar to that of other ant-eating mammals.
The sloth bear is one of eight extant species in the bear family Ursidae and of six extant species in the subfamily Ursinae.
Characteristics
Sloth bears adults are medium-sized bears. The typical weight range for females is from , and for males is from . Exceptionally large female specimens can reach and males up to .Johnsingh, A. J. T., & Manjrekar, N. (Eds.). (2013). Mammals of South Asia. Universities Press. The average weight of sloth bears from the nominate subspecies in Nepal was in females and in males.Joshi, A. R., Smith, J. L., & Garshelis, D. L. (1999). Sociobiology of the myrmecophagous sloth bear in Nepal . Canadian Journal of Zoology, 77(11), 1690–1704. Nominate bears in India were found to weigh average in males and in female per one study.Shanmugam, A. A., Kumar, J. K., Selvaraj, I., & Selvaraj, V. (2008). Hematology of sloth bears (Melursus ursinus ursinus) from two locations in India . Journal of wildlife Diseases, 44(2), 509–518. Specimens from Sri Lanka (M. u. inornatus) may weigh up to in females and in males.de Silva Wijeyeratne, G. (2016). Mammals of Sri Lanka . Bloomsbury Publishing. However six Sri Lankan male sloth bears averaged only , and was the average for four females, so Sri Lankan bears could be around 30% lighter in body mass than nominate race bears and with more pronounced size sexual dimorphism.Ratnayeke, S., Van Manen, F. T., & Padmalal, U. K. G. K. (2007). Home ranges and habitat use of sloth bears Melursus ursinus inornatus in Wasgomuwa National Park, Sri Lanka. Wildlife Biology, 13(3), 272–284. They are high at the shoulder, and have a body length of .Brown, "Bear Anatomy and Physiology"Grzimek, B. (1990). Grzimeck's Encyclopedia of mammals (No. 599.03 G7). Besides being smaller than males, females reportedly typically have more fur between their shoulders.
Sloth bear muzzles are thick and long, with small jaws and bulbous snouts with wide nostrils. They have long lower lips which can be stretched over the outer edge of their noses, and they lack upper incisors, thus allowing them to suck up large numbers of insects. The premolars and molars are smaller than in other bears, as they do not chew as much vegetation. In adults, the teeth are usually in poor condition, due to the amount of soil they suck up and chew when feeding on insects. The back of the palate is long and broad, as is typical in other ant-eating mammals. The paws are disproportionately large, and have highly developed, sickle-shaped, blunt claws which measure in length. Their toe pads are connected by a hairless web. They have the longest tail in the bear family, which can grow to . Their back legs are not very strong, though they are knee-jointed, and allow them to assume almost any position. The ears are very large and floppy. The sloth bear is the only bear with long hair on its ears.
Sloth bear fur is completely black (rusty for some specimens), save for a whitish Y- or V-shaped mark on the chest. This feature is sometimes absent, particularly in Sri Lankan specimens. This feature, which is also present in Asian black bears and sun bears, is thought to serve as a threat display, as all three species are sympatric with tigers (tigers usually do not carry out attacks on an adult bear if the bear is aware or facing the cat). The coat is long, shaggy, and unkempt, despite the relatively warm environment in which the species is found, and is particularly heavy behind the neck and between the shoulders, forming a mane which can be long. The belly and underlegs can be almost bare. Sloth bears are usually about the same size as an Asian black bear but are immediately distinctive for their shaggier coat, whitish claws, as well as their typically rangier build. Their head and mouth is highly distinct from that of a black bear with a longer, narrower skull shape (particularly the snout), loose-looking, flappier lips and paler muzzle colour. In few areas of overlap, sloth bear confusion with sun bears is unlikely, given the latter species considerably smaller size, much shorter fur, wrinkled folding skin (especially around the back), bolder chest marking and drastically different, more compact head structure and appearance.WildLifeInformation.org , Melursus ursinus – Sloth bear
Distribution and habitat
The sloth bear's global range includes India, the Terai of Nepal, temperate climatic zones of Bhutan and Sri Lanka. It occurs in a wide range of habitats including moist and dry tropical forests, savannahs, scrublands and grasslands below on the Indian subcontinent, and below in Sri Lanka's dry forests. It is regionally extinct in Bangladesh.
Behaviour and ecology Adult sloth bears may travel in pairs. Males are often observed to be gentle with cubs. They may fight for food. They walk in a slow, shambling motion, with their feet being set down in a noisy, flapping motion. They are capable of galloping faster than running humans.Brown, "Bear Behavior and Activities" Although they appear slow and clumsy, both young and adult sloth bears are excellent climbers.Servheen, p. 219 They occasionally will climb to feed and to rest, though not to escape enemies, as they prefer to stand their ground. Sloth bear mothers carry their cubs up trees as the primary defense against attacks by predators instead of sending them up trees. The cubs can be threatened by predators such as tigers, leopards, and other bears.Servheen, p. 226 They are adequate climbers on more accessible trees but cannot climb as quickly or on as varied surfaces as can black bears due to the sloth species' more elongated claw structure. Given their smaller size and still shorter claws, sloth bear cubs probably climb more proficiently than adults (much as brown bear cubs can climb well but not adults). They are good swimmers, and primarily enter water to play.
To mark their territories, sloth bears scrape trees with their forepaws, and rub against them with their flanks. Sloth bears are recorded to produce several sounds and vocals. Howls, squeals, screams, barks and trumpet-like calls are made during aggressive encounters while huffing is made as a warning signal. Chuffing calls are made when disturbed. Females keep in contact with their cubs with a grunt-whicker while cubs yelp when separated.
Reproduction
The breeding season for sloth bears varies according to location: in India, they mate in April, May, and June, and give birth in December and early January, while in Sri Lanka, it occurs all year. Sows gestate for 210 days, and typically give birth in caves or in shelters under boulders. Litters usually consist of one or two cubs, or rarely three. Cubs are born blind, and open their eyes after four weeks. Sloth bear cubs develop quickly compared to most other bear species: they start walking a month after birth, become independent at 24–36 months, and become sexually mature at the age of three years. Young cubs ride on their mother's back when she walks, runs, or climbs trees until they reach a third of her size. Individual riding positions are maintained by cubs through fighting. Intervals between litters can last two to three years.
Dietary habits