Sloth bears are distinguished from Asian black bears by their larger builds, longer, shaggier coat, pale muzzle and white claws.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 the nose, and 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 dirt 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 4 inches in length. Their toe pads are connected by a hairless web. They have the longest Tail in the bear family, which can grow to 6-7 inches. Their back legs are not very strong, though they are knee-jointed, and allow the sloth bear to assume almost any position. The ears are very large and floppy. 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. The coat is long, shaggy and unkempt, and is particularly heavy behind the neck and between the shoulders, forming a mane which can be 30 cm long.The belly and underlegs are almost bare. Adult sloth bears usually weigh 220 lbs, though they can reach up to 300 lbs. They are 2.3 feet high at the shoulder, and have a body length of 5-6 feet. Females are smaller than males, and have more fur between the shoulders.
Adult sloth bears may travel in pairs, with the males being 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. Although they appear slow and clumsy, sloth bears are excellent climbers. They climb to feed and rest, though not to escape enemies, as they prefer to stand their ground. They are capable of climbing on smooth surfaces and hang upside down like sloths. They are good swimmers, and primarily enter water to play. To mark their territory, sloth bears will scrape trees with their forepaws, and rub against them with their flanks. Sloth bears have a great vocal range. Gary Brown, in his Great Bear Almanac lists over 25 different sounds in 16 different contexts. Sounds such as barks, screams, grunts, roars, snarls, wickers, woofs and yelps are made when angered, threatening or when fighting. When hurt or afraid, they shriek, yowl or whimper. When feeding, sloth bears make loud huffing and sucking noises, which can be heard over 100 metres away. Sounds such as gurgling or humming are made by bears resting or sucking their paws. Sows will emit crooning sounds to their cubs. The species is the most vociferous when mating, and make loud, melodious calls when doing so. Sloth bears do not hibernate. They make their day beds out of broken branches in trees, and will rest in caves during the wet season. Sloth bears are the most nocturnal of bears, though sows become more active in daytime when with cubs.
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 can be done all year. Sows gestate for 210 days, and typically give birth in caves or in shelters under boulders. Litters usually consist of 1-2 cubs, rarely 3. Cubs are born blind, and open their eyes after four weeks. Sloth bear cubs develop fast compared to most other bear species: they will start walking a month after birth, become independent at 24-36 months, and become sexually mature at the age of 3 years. Young cubs will 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 2-3 years.
Sloth bears are expert hunters of termites, which they locate by smell. On arriving at an ant-hill, they scrape at the structure with their claws till they reach the large combs at the bottom of the galleries, and will disperse the dirt with violent puffs. The ants are then sucked up through the muzzle, producing a hoovering sound which can be heard 180 meters away. Their olfactory senses are strong enough to detect grubs three feet below ground. Unlike other bears, they do not congregate in feeding groups. They rarely prey on other mammals. Sloth bears may supplement their diet with fruit and plant matter: in March and April, they will eat the fallen petals of mowha trees and are partial to mangoes, sugar cane, the pods of the Golden Shower Tree and the fruit of the jack-tree. Sloth bears are extremely fond of honey. When feeding their cubs, sows are reported to regurgitate a mixture of half digested jack fruit, wood apples and pieces of honey comb. This sticky substance hardens into a dark yellow circular bread-like mass which is fed to the cubs. This “bear’s bread” is considered a delicacy by some of India’s natives.
Relationships with other animals
Bengal tigers will occasionally prey on sloth bears. Tigers usually give sloth bears a wide berth, though some specimens may become habitual bear killers and it is not uncommon to find sloth bear fur in tiger scats. Tigers typically hunt sloth bears by waiting for them to feed on ant-hills, then creep behind them and seize them by the back of their necks and force them to the ground with their weight. One tiger was reported to simply break its victim’s back with its paw, then wait for the paralysed bear to exhaust itself trying to escape before going in for the kill. When confronted by tigers face to face, sloth bears will charge at them, crying loudly. A young, or already satiated tiger will usually retreat from an assertive sloth bear, as the bear’s claws can inflict serious wounds. Sloth bears may scavenge on tiger kills. As tigers are known to mimic the calls of sambar deer to attract them, sloth bears react fearfully even to the sounds made by deer themselves. Indian leopards can also be a threat, as they are able to follow sloth bears up trees. Sloth bears will occasionally chase leopards from their kills.
Sloth bears are sympatric with Asiatic Black Bears in Northern India, and the two species, along with the sun bear, co-exist in some of the national parks and wildlife sanctuaries. They are also found together in Assam, Manipur and Mizoram, in the hills south of the Brahmaputra river, the only places occupied by all three bear species. The three species do not act aggressively toward each other.
Dhole packs may attack sloth bears, though they are not a usual prey item. When attacking sloth bears, dholes will try to prevent the bear from retreating in caves.
Asian elephants apparently do not tolerate sloth bears in their vicinity. The reason for this is unknown, as individual elephants known to maintain their composure near tigers have been reported to charge bears. Indian rhinoceros have a similar intolerance for sloth bears, and will charge at them.