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Ursus thibetanusAsiatic black bear

By Tracie Goodness

Geographic Range

Ursus thibetanus is widely distributed. Asiatic black bears can be found north of Pakistan, south of Afghanistan, east of the Himalayans, north of Vietnam, south of China, and in Thailand. (Than, et al., 1998)

Habitat

Asiatic black bears live in moist forests, on steep mountains, and in areas where the vegetation is thick. They live at higher elevations in the summer, and descend during the winter. Occasionally, they come out of the forests to forage on plains. ("Asiatic Black Bears", 2004; Than, et al., 1998)

  • Range elevation
    0 to 3600 m
    0.00 to 11811.02 ft
  • Average elevation
    1000 m
    3280.84 ft

Physical Description

The size differs between males and females. Males typically weigh 110 to 150 kg, while females weigh 65 to 90 kg. The head and body measure 120 to 180 cm in length, while the tail is an additional 6.5 to 10.6 cm. The head is large and rounded, and the eyes are small. The ears are large and are set farther apart than on an American black bear. The body is heavy, the legs are thick and strong, and the paws are broad. The stance is plantigrade. The tail is short and is barely visible under a long, coarse coat. The black pelage has a light beige to white “V” shape on the chest area, a small beige to white colored crescent across the throat, and a small spot of white on the chin. The white fur on the muzzle seldom reaches the orbits of the bear.

The skull of U. thibetanus is typical of the Suborder Caniformia, bearing a long rostrum. However, the orbits are typically smaller than those of most caniforms. The width of the mastoid rarely exceeds the length of the palate. The auditory bullae are flat. The muzzle is long and narrow, and does not extend very far over the canines. The dental formula is usually 3/3, 1/1, 4/4, 2/3 = 42. However, the premolars can sometimes be lost as the bear ages. The postcarnassial teeth are enlarged, and occlusal surfaces are adapted to crushing. Normally, there is a diastema between the premolars. The upper carnassial of U. thibetanus is triangular. ("Asiatic Black Bears", 2004; Than, et al., 1998; Lekagul and McNeely, 1988; Nowak, 1991; Czaplewski, et al., 2000)

  • Sexual Dimorphism
  • male larger
  • Range mass
    65 to 150 kg
    143.17 to 330.40 lb
  • Average mass
    100 kg
    220.26 lb
  • Range length
    120 to 180 cm
    47.24 to 70.87 in

Reproduction

Little is known about Asiatic black bears in the wild; most of what is known about their social and reproductive behavior has been collected by observing the bears in zoos and environments other than their natural habitat.

In captive environments, the mating pattern of Asiatic black bears is classified as promiscuous. Females enter periods of estrus and non-estrus at irregular intervals, and undergo mating for 12 to 35 days. For males above the age of 6 years, larger bears spend more days mating than smaller males. There is a social hierarchy related to the age and body weight of male bears and only larger males mate with the females. Those of small size (those weighing less than 80 kg) have reduced chances of mating.

In the wild, Asiatic black bears typically forage alone. However, during breeding season, pairs can be seen hunting and gathering together. ("Asiatic Black Bears", 2004; Than, et al., 1998; Nowak, 1991; Yamamoto, et al., 1998)

The reproductive patterns vary widely in the different populations of U. thibetanus. In Siberia, mating takes place in June or July, with the births occurring in February, typically. In Pakistan, mating occurs in October, and births occur in February. Across the species, breeding usually begins when U. thibetanus is 3 to 4 years old. The pregnancy lasts from 7 to 8 months, and cubs are born in a cave or hollow tree in early winter. There are usually 2 cubs per litter, and the cubs typically weigh about 8 to 10.5 ounces. Asiatic black bears are thought to have delayed implantation where the embryo floats freely in the womb before it implants in the uterine lining, though this is not known definitively. Studies conducted on pregnant and nonpregnant bears show that concentrations of serum progesterone (P4) and prolactin (PRL) might be connected with the process of delayed implantation in U. thibetanus. Lower concentrations of both P4 and PRL are found in nonpregnant bears. Increased concentrations of these cause the activation of the corpus luteum, which prepares the uterus for implantation. Rising levels of both P4 and PRL are found to occur approximately two months after copulation. Therefore the duration of the delayed implantation in U. thibetanus is around two months. It is not yet known whether delayed implantation occurs all of the time in U. thibetanus, or only under certain circumstances. It is also not yet known what causes the levels of the particular hormones under study to change, though it may be due to environmental cues or in response to other hormones circulating in the body. ("Asiatic Black Bears", 2004; International Fund for Animal Welfare, 2003; Izumiyama, et al., 2001; Than, et al., 1998; Nowak, 1991; Sato, et al., 2001)

  • Breeding interval
    The breeding interval is not known for sure; Asiatic Black Bears have been seen with two litters of cubs, but in the wild they typically only have one litter of cubs at a time. Since the young stay with the mother for 2 to 3 years, the breeding interval could therefore be 1 litter every 2 to 3 years, or more.
  • Breeding season
    Late Summer; From June to October, depending on which population is being observed
  • Average number of offspring
    2
  • Average number of offspring
    2
    AnAge
  • Range gestation period
    7 to 8 months
  • Average weaning age
    3.5 months
  • Range time to independence
    2 to 3 years
  • Range age at sexual or reproductive maturity (female)
    3 to 4 years
  • Range age at sexual or reproductive maturity (male)
    3 to 4 years

The cubs of U. thibetanus cannot open their eyes until 1 week has passed, and they are not fully weaned until just over 3 months. The cubs live with their mother until they are 2 to 3 years old. Not much is known about the type of care that parents provide in the wild, due to the lack of studies of behavior outside of captive environments. (Nowak, 1991)

  • Parental Investment
  • altricial
  • pre-weaning/fledging
    • provisioning
      • female

Lifespan/Longevity

Little is known about lifespan in U. thibetanus, especially out in the wild. There are few resources available for information on lifespan in the wild or in captivity. (International Fund for Animal Welfare, 2003; Nowak, 1991)

Behavior

Asiatic black bears are primarily nocturnal feeders and sleep in a tree hole or in a cave during the daytime, but they do sometimes forage diurnally. During the autumn, their nocturnal activity increases. They shift their ranges in early autumn in order to obtain native broadleaved food species (mast crops) at lower elevations. They are powerful swimmers, and their short (2 inches, or 5.08 cm) claws make them adept tree climbers. They are plantigrade, and typically walk on four feet, but when they fight, they stand up on their two hind feet and slap their enemy with their forepaws. Asiatic black bears usually avoid man and only attack when they are wounded or trying to protect their young, but unprovoked attacks have been documented many times throughout history.

Not all Asiatic black bears hibernate, though many do. They store fat during the late summer to use during the winter months of hibernation. Some may sleep the entire winter period, while others may only hibernate for the worst periods of winter weather. Asiatic black bears behave as other bears during hibernation; they do not excrete urea or solid fecal material, instead converting the waste material to proteins. During periods of hibernation, the heartbeat drops from 40 to 70 beats per minute to 8 to 12 beats per minute, and the metabolic rate decreases by 50%. The body temperature decreases by only 3 to 7 degrees Centigrade. Due to the fact that the body temperature of U. thibetanus, as well as many other bears, does not substantially drop and the bear can be easily awakened, some ecophysiologists do not consider the bear's period of inactivity to be true hibernation. Others argue that it is true hibernation, due to the fact that the pulse rate drops by 50%. ("Asiatic Black Bears", 2004; Nowak, 1991; Reid, et al., 1991; Czaplewski, et al., 2000)

  • Range territory size
    6.4 to 36.5 km^2

Home Range

The territory of U. thibetanus can vary greatly, from around 6.4 or 9.7 square kiliometers to around 16.4 or 36.5 square kilometers, depending on the availability of food. The denser the available food supply is, the smaller the range. (Nowak, 1991; Reid, et al., 1991)

Communication and Perception

Exceptional sight, hearing, and smell are characteristics of U. thibetanus. No studies are available as to the exact form of communication between Asiatic black bears. However, extensive research has been conducted on other members of the family Ursidae that have senses similar to those of the Asiatic black bear. Using evidence from these studies, it can be inferred that Asiatic black bears communicate vocally and use their heightened sense of hearing to aid in listening to these vocalizations. For example, when bear cubs are separated from their mothers, they make crying calls. Low guttural noises can be indications of a bear being apprehensive, and clicking the teeth together is an indication of aggressiveness.

Bears often communicate visually with each other by the way in which they move or behave in the presence of other bears; for example, the behavior of a bear can convey either dominant or subordinate status to another. To indicate subordinate status, a bear moves away, or sits or lies down. To convey dominance, a bear walks or runs towards a rival.

Bears use their acute sense of smell in order to communicate with other members of their species; they do so by urinating, defecating, and by rubbing against trees to leave their scent for other bears to detect. ("Living In Harmony With Bears", 2000; Than, et al., 1998)

Food Habits

Asiatic black bears most often feed diurnally. However, their nocturnal activity increases through autumn. This occurs because the bears must increase their food intake in order to store body fat for insulation and caloric needs for use during harsh winters and hibernation. Asiatic black bears seem to be able to shift their circadian rhythm in order to obtain desired foods; for example, when raiding crops, they are more likely to do so at night in order to avoid contact with humans. Asiatic black bears posses an acute sense of smell that lets them locate grubs and other insects up to 3 feet (approximately 1 meter) below the ground. Asiatic black bears are omnivorous, though they are primarily vegetarians. A recent study showed that nuts from Fagaceae trees occupied the highest proportion of autumn foods. When food production and availability is poor, Asiatic black bears have been known to strip the bark off of trees in order to supplement their deficient diet with nutrients. Their normal diet consists of fruits, roots and tubers, as well as small invertebrates and vertebrates, and carrion. However, cases in which they eat buffalo by breaking the neck have been documented. They also eat other prey they find that tigers have killed.

Asiatic black bears have been known to eat any available food source, including the livestock and produce of farms. Their proclivity for domestic animals and crops has made humans target them, and Asiatic black bears are often killed while trying to feed. ("Asiatic Black Bears", 2004; Hashimoto, et al., 2003; Hayashi, et al., 2002; Nowak, 1991; Reid, et al., 1991; Czaplewski, et al., 2000)

  • Animal Foods
  • mammals
  • carrion
  • insects
  • terrestrial worms
  • Plant Foods
  • roots and tubers
  • wood, bark, or stems
  • fruit

Predation

The main predator of U. thibetanus is the Siberian tiger (Panthera tigris). The fact that tiger kills are a favorite food of U. thibetanus leaves it susceptible to tiger attacks when the tiger returns to its kill and finds the bear feeding on the carrion. (Than, et al., 1998)

Ecosystem Roles

Asiatic black bears are the prey of Siberian Tigers. Asiatic black bears feed upon the carrion that the tigers kill, and if the bears are caught while feeding, they are killed and eaten by the tigers.

Asiatic black bears feed upon grubs and insects, placing them on the third trophic level. As omnivores, they are secondary consumers.

Studies conducted in various locations in Japan show that there are a few typical parasites of Asiatic black bears, occurring in the esophageal and tracheal connective tissue, lungs, and ventral body hair.

Three common nematode parasites found in the esophageal and tracheal connective tissue of Asiatic black bears are Baylisascaris transfuga , Cercopithifilaria japonica , and the filarial nematode Dirofilaria ursi. The biting louse Trichodectes pinguis is found in the ventral body hairs, as well as numerous species of the hard tick Haemaphysalis megaspinosa. There has been one instance in which Hepatozoon canis was found in the lungs of an Asiatic black bear. This was the first time this parasite has been found in any species of bear. ("Ecosystem processes", 2004; Than, et al., 1998; Uni, et al., 1995; Uni, et al., 2003; Yokohata, et al., 1990)

Economic Importance for Humans: Positive

The bile and gallbladders of Asiatic black bears are harvested for medical use in some oriental countries. These organs are thought to reduce inflammation and reduce fevers.

Asiatic black bears are also hunted for their paws, skin, and meat. ("Asiatic Black Bears", 2004; "Threatened Species; Ursus thibetanus", 1996; International Fund for Animal Welfare, 2003)

Economic Importance for Humans: Negative

There have been documented cases of unprovoked attacks by Asiatic black bears on humans, as well as cases of provoked attacks on humans when a bear felt endangered. Most attacks on humans take place in the late summer, around the time of the mating season.

Asiatic black bears sometimes prey on livestock and crops, thus making themselves susceptible to being killed by humans when caught. ("Asiatic Black Bears", 2004; Chauhan, 2003)

  • Negative Impacts
  • injures humans
    • bites or stings
  • crop pest

Conservation Status

The habitat of U. thibetanus is threatened by uncontrolled harvesting and deforestation. There is no special effort being put forth to help the continuing decline in numbers of Asiatic black bears. Diversity of habitats and food is important in providing alternative foods when one food source fails. As a result of deforestation and other human activities, however, the diversity of habitats is being destroyed. Even in the protected areas, there is not enough variety to fully support the Asiatic black bears. As a result, each population of Asiatic black bears is becoming increasingly isolated.

Population studies in 2001 in Japan found that different populations of Asiatic black bears were becoming genetically isolated from each other. Even between the two closest populations, there was a low but significant amount of genetic differentiation. In the individual populations, genetic diversity was decreasing. Since each population was changing and evolving separately, genetic isolation between the populations is a problem that needs to be addressed, and conservation efforts must be initiated. ("Asiatic Black Bears", 2004; Saitoh, et al., 2001; Nowak, 1991; Reid, et al., 1991)

Contributors

Matthew Wund (editor), University of Michigan-Ann Arbor.

Tracie Goodness (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

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.

arboreal

Referring to an animal that lives in trees; tree-climbing.

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.

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

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.

fertilization

union of egg and spermatozoan

forest

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

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

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

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

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

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

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

visual

uses sight to communicate

viviparous

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

References

2004. "Asiatic Black Bears" (On-line). Accessed February 01, 2004 at http://www.asiatic-black-bears.com/.

2004. "Ecosystem processes" (On-line). Accessed February 11, 2004 at http://www.cord.edu/faculty/landa/courses/e103w00/sessions/ecosystem.html.

2000. "Living In Harmony With Bears" (On-line). Accessed February 12, 2004 at http://www.audubon.org/chapter/ak/ak/images/LIHWB%202002.pdf.

1996. "Threatened Species; Ursus thibetanus" (On-line). Accessed February 01, 2004 at http://www.redlist.org/search/details.php?species=22824.

Chauhan, N. 2003. Human casualties and livestock depredation by black and brown bears in the Indian Himalaya, 1989-98.. Ursus, 14(1): 84-87.

Czaplewski, N., T. Vaughan, J. Ryan. 2000. Mammalogy. United States of America: Thomson Learning, Inc..

Hashimoto, Y., M. Kaji, H. Sawada, S. Takatsuki. 2003. Five-year study on the autumn food habiots of the Asiatic black bear in relation to nut production. Ecological Research, 18: 485-492.

Hayashi, S., Y. Yoshida, M. Horiuchi, T. Tsubota, T. Murase, T. Okano, M. Sato, K. Yamamoto. 2002. Analysis of causes of bark stripping by the Japanese black bear (Ursus thibetanus japonicus). Honyurui Kagaku, 42(1): 35-43.

International Fund for Animal Welfare, 2003. "Asiatic black bear or Moon bear" (On-line). Accessed March 07, 2004 at http://www.ifaw.org/ifaw/general/default.aspx?oid=12973.

Izumiyama, S., T. Yoshida, H. Hayashi, O. Huygens. 2001. Denning Ecology of Two Populations of Asiatic Black Bears in Nagano Prefecture, Japan. Mammalia, 65: (4): 417-428.

Lekagul, B., J. McNeely. 1988. Mammals of Thailand. Bangkok, Thailand: Darnsutha Press.

Nowak, R. 1991. Walker's Mammals of the World, Fifth Edition. Baltimore and London: Johns Hopkins University Press.

Reid, D., M. Jiang, Q. Teng, Z. Qin, J. Hu. 1991. ECOLOGY OF THE ASIATIC BLACK BEAR URSUS-THIBETANUS IN SICHUAN CHINA. Mammalia, 55(2): 221-237.

Saitoh, T., Y. Ishibashi, H. Kanamori, E. Kitahara. 2001. Genetic status of fragmented populations of the Asian black bear Ursus thibetanus in western Japan. Population Ecology, 43(3): 221-227.

Sato, M., T. Tsubota, T. Komatsu, G. Wantanabe, K. Taya, T. Murase, I. Kita, T. Kudo. 2001. Changes in sex steroids, gonadotropins, prolactin, and inhibin in pregnant and nonpregnant Japanese black bears (Ursus thibetanus japonicus). Biology of Reproduction, 65(4): 1006-1013.

Than, U., S. Simcharoen, B. Kanchanasakha. 1998. Carnivores of Mainland South East Asia. Bangkok: Siam Tong Kit Printing Co., Ltd..

Uni, S., M. Mastsubayashi, E. Ikeda, Y. Suzuki. 2003. Characteristics of a hepatozoonosis in lungs of Japanese black bears. Journal of Veterinary Medical Science, 65(3): 385-388.

Uni, S., Y. Suzuki, M. Harada, I. Kimata, M. Iseki. 1995. Prevalence of nematodes in the Asiatic Black Bear, Ursus thibetanus, in Central Honshu, Japan, with an amended description of Cercopithifilaria japonica (syn. Dipetalonema (Chenofilaria) japonica). Japanese Journal of Parasitology, 44(5): 371-376.

Yamamoto, K., T. Tsubota, I. Kita. 1998. Observation of sexual behavior of captive Japanese black bears, Ursus tibetanus japonicus. Journal of Reproduction & Development, 44(5): 13-18.

Yokohata, Y., O. Fujita, M. Kamiya, T. Fujita, K. Kaneko, M. Ohbayashi. 1990. Parasites from the Asiatic Black Bear (Ursus thibetanus) on Kyushu Island, Japan. Journal of Wildlife Diseases, 26(1): 137-138.

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