The sloth bear is a species of bear endemic to the Indian subcontinent that is thought to have evolved into it current form during the early Pleistocene Epoch approximately 1.8 million years ago (Bears of the World). Its name is misleading in that the sloth bear is not related to the two or three toed sloth species in any way. It is thought that perhaps the individual who initially named the bear took its haggard appearance and prominent claws to mean that it was in some way linked ancestrally to the sloth. However, the long, shaggy coat of the bear and its long claws are adaptations made by the species unrelated to the similar adaptations of the sloth to the cold weather and diet of the bear. There are two subspecies of the sloth bear: the larger Indian sloth bear (Melrusus ursinus ursinus) and the Sri Lankan sloth bear (Melrusus ursinus inornatus) which has a shorter coat and smaller stature than its Indian counterpart. While both bears are endemic to the Indian subcontinent, they are found in different places in this region; the Indian sloth bear inhabits forested and grassland regions of India, Bhutan, Nepal, and Bangladesh while the Sri Lankan sloth bear is only found on the island of Sri Lanka.
Phylogeny of Ursidae based on mitochondrial DNA analysis
Source: Yoganand, et al
Like most species, the sloth bear has been classified and re-classified over the years as more and more is learned about the species. Initially, the bear was given the taxonomic name of Bradypus ursinus meaning "bear-like sloth," however, it was soon realized that although the bear bore a striking resemblance and shared characteristics such as its shaggy coat and missing upper incisors with the sloth, it was a member of the bear family; as a result, it was placed in the genusUrsus. However, DNA and phylogenetic research revealed that the sloth bear had diverged from the sun bear, brown bear, polar bear, American black bear, and Asiatic black bear 12 million years before present and, therefore, was given its own genus Melursus (Yoganand, 2008).
The sloth bear is unique in its appearance standing out amongst other bear species with a distinct snout and thick coarse fur. The snout of this species of bear is longer and less hairy than those of other bear species. This is likely an adaptation to accomodate a diet of mostly insects. In addition, the sloth bear as the unique ability to close its nostrils in order to avoid inhaling dirt whilst scavenging for insects on the forest floor. These bears can extend their lips beyond their nose and typically lose their two upper incisors by the age of two in order to allow them to suck insects off the ground. This sucking sound is extremely loud being able to be heard up to 300 meters away. The coat of the sloth bear is typically long and shaggy however this varies by season; its hair is the longest behind its ears and at the back of its neck. Its long hair gives the bears the appearance of being much larger than they actually are. They are about 2-3 feet in height at the shoulder and weigh an average of about 220 pounds as adults (Yoganand, 2006). Sloth bears have an off-white or yellow v-shaped marking on their chests typically only seen if the bears stand on their hind legs. The front legs of the bears are curved inwards and webbed in addition to having 3 inch claws - all useful adaptations to digging for ants and termites. Although not considered by most to be the most charismatic of the bear family, the sloth bear's unique appearance reflects the useful adaptations the species has made to fill its specific niche in its environment.
Sloth bears, like most members of the family Ursidae, are solitary creatures often only coming into contact with others of the species while mating. Despite this trend, some adults have been known to travel in pairs with adult males being gentle with cubs. A unique characteristic of this species is the carrying of cubs on the mother's back until they are able to keep up with the adults. These bears are generally nocturnal however, females with cubs commonly are most active during the day in order to avoid predators active at night. Another possible reason why these bears were given the moniker they were was because of the slow, ambling gaite of the animals. Although they may look clumsy to observers, these bears can run faster than the average human and are extremely agile climbers. However, they do not generally climb trees when startled due to the high number of predators in their habitat that can also climb trees extremely quickly. They are also excellent swimmers and have been known to enter water to play. Although these bears are not generally aggressive, they may fight for food if presented with a confrontational opportunity. Mating season varies depending on location with females typically giving birth to 1-2 cubs (Bears of the World). The cubs are born blind only opening their eyes after 4 weeks and walking at about 1 month. The cubs stay with their mother until between 24 and 36 months of age. The diet of sloth bears consists mainly of termites which they are experts in hunting with adaptations to finding and digging them up. They are the only bear species adapted specifically for myrmecophagy, or ant and termite eating. They rarely prey on other animals and do no congregate in feeding groups as do other members of the family Ursidae. They supplement their diet of ants and termites with fruit and plant matter.
The Sloth Bear is endemic to the Indian Subcontinent historically inhabiting India, Bangladesh, Sri Lanka, Nepal, and Bhutan. They have a wide range of habitats including wet or dry tropical forests, savannas, scrublands, and grasslands. They are typically a lowland species remaining below 1,500 meters although they have been known to live as high as 2,000 meters in the Western Ghats region (Garshelis, 2008). In areas where the daytime temperature is hot, the bears will typically retreat to thickets, tree cavities, or rock outcrops to avoid the heat and maintain a nocturnal lifestyle. In Nepal and Sri Lanka, sloth bears are known to avoid human populations and therefore have little of an effect on cropland in those regions. Conversely, sloth bears in India frequently raid agricultural lands as a result of human encroachment on their territory. Sloth bear ranges are relative small in comparison to other bear species as a result of their different diet. While all other bears are predominantly carnivores typically requiring large expanse of land to hunt large prey, sloth bears' myrmecophagous diet allows the species to have much smaller range requirements as they do not need to go far to find what they are looking for.
The IUCN classifies the sloth bear as a vulnerable species as of 1996. Before 1990, not enough data was available to determine the status of the bears but following a study conducted by the IUCN in 1990, sloth bears were listed as vulnerable on the Red List. It is estimated that only about 20,000 bears are left in the wild with less than 10,000 of those being mature adults. Additionally, evidence suggests that as a result of range reduction, the population of sloth bears has decreased 30-49% in the last 30 years (IUCN, 2011). Habitats in Bangladesh are under particular pressure as the bears in this region inhabit the lowland areas often occupied by human populations. It is unknown whether or not the bears have gone extinct from this part of their range.
Sloth bears face many different threats in its natural habitat on the Indian subcontinent. The small body size and adaptations to accomodate its diet has resulted in a less ferocious bear than typically imagined. Tigers and leopards are known predators of the sloth bear generally attacking the bears from behind and much more likely to attack bears with cubs than bears without. Despite its natural predators, habitat loss is the largest threat to sloth bear populations in the wild. Population growth in this region of the world has been exponential in the past decade with numbers growing at the second fastest rate in the world. Resultant of this rapid growth, expansion into formerly untouched land has become common place. Sloth bears are being pushed onto smaller and smaller plots of land that are unable to sustain large numbers of the solitary animals. Additionally, as the fringe of civilization approaches sloth bear habitat, the bears are coming into contact with human populations more frequently than ever before resulting conflicts that typically end badly for the bears. Attacks on humans may end in destroying the bear. The encroachment of humans on sloth bear ranges includes building roads through habitats, establishment of monoculture plantations, settlement of refugees, and expansion of agriculture. All of these actions result in smaller and less suitable habitats for sloth bears thus reducing their numbers in the wild. Another issue the bears face is poaching - male parts of bears are thought to be an aphrodisiac in some Asian cultures, bones, teeth and claws are used to ward off evil spirits, and bear fat and gall bladders are used in medicines. Sloth bears are considered to be pests by some communities justifying killing the bears by saying that the they are killing livestock or threatening the human population of an area.
India's Dancing Bears This cruel tradition in India began during the 16th Century and persisted for over 400 years. Cubs less than a year old were taken from their mothers had ropes or chains forced through their noses and most of their teeth removed without anaesthesia and then were starved and beaten by their trainers trying to teach them to "dance." They were used as a street acts often seen on the sides of roads with their owners pulling on the ropes attached through their nose to perform. Often, these bears did not live past 8 years, less than one-third a sloth bear's typical lifespan (Kirby, 2003). Fortunately, this practice was outlawed in 1972 by Parliament under the Wildlife Protection Act and the last dancing bear was freed in 2009. This is a success story for conservationalists and animal advocates all over the world.
Great work, Emily! Very interesting!
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