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Melursus ursinussloth bear

By LeeAnn Bies

Geographic Range

Melursus ursinus is found throughout India, Sri Lanka, and further north into Bangladesh, Nepal, and Bhutan. This species was fairly common in India and Sri Lanka until as recently as 20 years ago, now they are harder to find (Ward and Kynaston, 1995).

Habitat

Sloth bears live mainly in tropical areas. They can be found in forested areas and grasslands. They are more frequently found at lower elevations and seem to prefer drier forests and areas with rocky outcrops (Ward and Kynaston, 1995; IBA, 1999).

Physical Description

Sloth bears have a shaggy black coat, especially over the shoulders. Brown and grey hairs found on the coat give the appearance of a cinnamon color on some bears. This heavy coat may be an adaptation to deal with cold. These bears have long snouts, which are similar to but less elongate than those of anteaters. The molars are broad and flat, representing a trend away from carnivory. The body structure of M. ursinus is awkward with huge feet and enormous claws. Sloth bears are nevertheless capable of galloping faster than a person can run. Compared to the body, the face appears naked and grey. They have extremely large tongues, a mobile snout, and they can voluntarily open and close their nostrils, all of which prove helpful with their diets. These bears have a light "U" or "Y" shaped patch on their chests. The color of these markings varies from white to yellow to chesnut brown. Females can weigh between 55 and 95 kg. Males are 30 to 40% heavier than females and can weigh between 80 and 140 kg. Adults measure 60 to 90 cm at the shoulder. (Blomstrom, 2000; International Association for Bear Research and Management (IBA), September 22, 1999; Sanderson, 1972; Ward and Kynaston, 1995)

  • Sexual Dimorphism
  • male larger
  • Range mass
    55 to 140 kg
    121.15 to 308.37 lb
  • Range length
    1.5 to 1.9 m
    4.92 to 6.23 ft
  • Average basal metabolic rate
    47.064 W
    AnAge

Reproduction

Sloth bears tend to be very noisy during mating (Blomstrom, 2000).

Information on the reproductive behavior of M. ursinus varies. Some studies have them mating mostly between May and July, whereas others report mating and giving birth at any tiime of year. These differences may be due to the location of the bears studied. Field studies in India found sloth bears to mate mostly in June. On the other hand, field studies in Sri Lanka discovered they mate over a greater part of the year. In captivity, a pair only mates for about 1 to 2 days. Most births occur from September to January. Pregnancy lasts between 6 and 7 months. One to two offspring are usually born, rarely three, but it does occur. Females usually search for a cave or a ground shelter in which to give birth (Ward and Kynaston, 1995; Sanderson, 1972; IBA, 1999; Blomstrom, 2000).

  • Breeding season
    depends on location
  • Range number of offspring
    1 to 3
  • Average number of offspring
    1.5
    AnAge
  • Average gestation period
    6-7 months
  • Average gestation period
    198 days
    AnAge
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1095 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1095 days
    AnAge

After birth (usually in a ground shelter of some sort), sloth bears are blind for about 3 weeks. Following a period of about 4 to 5 weeks the young leave the den. The cubs stay with their mother until they reach adulthood at about 2 to 3 years of age (Ward and Kynasaton, 1995; Blomstrom, 2000). Cubs often ride on the mother's back (Ward and Kynaston, 1995). Males are not reported to participate in parental care.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female

Lifespan/Longevity

Captive sloth bears have lived up to 40 years (Ward and Kynaston, 1995).

Behavior

Sloth bears are mainly nocturnal. Their sense of smell is well developed but their sight and hearing are poor. These bears are generally not aggressive, but their poor eyesight and hearing allows humans to draw near, and when feeling threatened these bears will defend themselves. Surprisingly, these bears are described as shy. For example, they live in the tropics but have long, dark, shaggy coats suggesting they are susceptible to cold stress. They are excellent climbers, but do not climb trees to escape danger. During the day they sleep in caves, especially caves by river banks. Not much is known about their social systems but evidence suggests they are solitary except for mothers with cubs. They do not hibernate, but do have a period of inactivity during the rainy season (Sanderson, 1972; Ward and Kynaston, 1995; IBA, 1999; Blomstrom, 2000).

Communication and Perception

Food Habits

Sloth bears are omnivorous, although their diet typically includes a large proportion of insect foods. Their diet includes leaves, honey, flowers, and fruits. During the months of March through June, fruits are more common and on occasion may make up 50% of these bears' diet. They prefer termite or bee nests and will do everything to get at them. While raiding termite nests these bears insert their long snouts into the nest, rip open the nest with their long claws, blow away the earth and dust, then feast on their prize by vacuuming the termites into their mouths. This sucking action is also accompanied with a series of puffings and belchings which can be heard up to 185 m away. The ability to voluntarily open and close the nostrils prevents the inhalation of dust during this process. Termites are a very secure food source, as they are present all year round. When nearby populated areas sloth bears feed on cultivated crops like sugar cane and maize (Ward and Kynaston, 1995; Sanderson, 1972).

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • fruit
  • flowers

Predation

These bears only risk predation from large predators such as tigers and leopards. Female sloth bears with cubs will occasionally vary from their nocturnal tendencies to avoid these nocturnal predators (Ward and Kynaston, 1995).

Ecosystem Roles

Since these bears include some fruit in their diet, they disperse the seeds of the fruit they eat. Also, by feeding on numerous amounts of termites, they keep the termite populations in check (Ward and Kynaston, 1995).

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

The gall bladders and fat of M. ursinus are used in traditional medicine (Ward and Kynaston, 1995).

Economic Importance for Humans: Negative

Sloth bears will enter crop fields such as maize. They also have a reputation for being unpredictable and aggressive (although this may be an unfair description) toward humans. They are quite possibly the most dangerous wild animal in Central India. When they are in human territory, or vice versa, numerous human casualties occur. One study found that between April 1989 and March 1994, there were 735 victims of sloth bear assaults and 48 were fatal (Rajpurohit and Krausman, 2000).

  • Negative Impacts
  • crop pest

Conservation Status

As is the case for many species, the destruction of sloth bears' habitats is a major cause for their rapidly declining numbers. Sri Lanka has lost about 1.85 million hectacres of natural high forest between 1956-1983. Reasons for the destruction include agricultural and developmental plans. An indirect threat to this species is the destruction of termite mounds for fine soil for tennis courts. Termites are a main source of food for these bears. These bears have also been hunted because of their reputation for aggression and crop destruction (Ward and Kynaston, 1995).

Other Comments

Early explorers observed that M. ursinus hung upside down in trees. This gave rise to the name "bear sloth." Sloth bears were trained by Qualanders, a nomadic group that roamed India and entertained crowds with performing animals and circus acts, and were the original dancing bears (Blomstrom, 2000; Conover, 2000).

Contributors

LeeAnn Bies (author), University of Michigan-Ann Arbor, Cynthia Sims Parr (editor), University of Michigan-Ann Arbor.

Glossary

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Blomstrom, D. 2000. "Sloth Bear" (On-line). Accessed October 30, 2001 at http://www.geobop.com/Mammals/Carnivora/Ursidae/Ursus_ursinus/.

Conover, A. January, 2000. Sloth bears: they eat ants, but take on tigers. Smithsonian, 10: 88-95.

International Association for Bear Research and Management (IBA), September 22, 1999. "Bear Species Descriptions" (On-line). Accessed October 30, 2001 at http://www.bearbiology.com/specdesc.html.

Rajpurohit, K., P. Krausman. Summer 2000. Human-sloth bear conflicts in Madhya Pradesh, India. Wildlife Society Bulletin, 28(2): 393-399.

Sanderson, I. 1972. Living Mammals of the World. Garden City, New York: Doubleday & Company.

Ward, P., S. Kynaston. 1995. Bears of the World. London: Blandford.

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