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a family of mammals of the order Carnivora. The head is elongated, the muzzle is massive, and the eyes and ears are small. The limbs are powerful and have digits; the walk is plantigrade. The claws are large and nonretractile. The tail is short. The body is heavily built, measuring up to 3 m long. The weight varies from 60 kg (sun bear) to more than 700 kg (polar bear). Thus, ursids are the largest living predators. The coat is dense, with a developed undercoat, and is relatively coarse. The color ranges from coal black to lemon white; some species have a light patch on the chest. The incisors and canines are large. The premolars are small and partially reduced, and the molars are massive and flattened. The sense of smell is highly developed, but vision and hearing are poor.
There are four (or seven) modern genera with seven (or nine) species: the spectacled bear (Tremarctos ornatus), which inhabits the mountainous regions of South America; the sun, or Malay, bear (Ursus [Helarctos] malayanus), the sloth bear (Melursusur-sinus), and the Asiatic black, or moon, bear (Ursus thibetanus), all of which are in Southeast Asia; the American black bear (Ursus americanus), which is distributed in North America; the Eurasian brown bear (Ursus arctos), which lives in northwestern Africa, in Eurasia, and in North America; and the polar bear (Ursus maritimus), which is distributed in the arctic.
Ursids live under the most diverse conditions, ranging from deserts to high mountains and from tropical forests to arctic ice floes. Consequently, their mode of life and eating habits differ. The Asiatic black bear, the American black bear, and the sun bear are good tree climbers and feed on various tree fruits. The sloth bear tears apart termite nests with its claws. The polar bear primarily hunts seals. The Eurasian brown bear lives under a variety of conditions. It inhabits steppes, deserts, subtropical forests, taigas, tundras, and seacoasts. It feeds on both animals and plants. In the fall it finds a den, where it spends the winter in deep sleep.
Ursids become sexually mature in the third or fourth year of life; they do not mate every year. The gestation period is seven months, and a single litter consists of one to five young. The life expectancy ranges from 30 to 40 years. Bear meat is edible; the fat and bile are used in medicine, and the hide is used to make rugs. Most commonly hunted is the Eurasian brown bear. The numbers and range of distribution of all ursids have been reduced sharply in the 20th century. In some countries the animals are protected by law, as for example, the polar bear in the USSR.
Fossil remains of ursids have been found in Middle Miocene deposits of Eurasia (genus Ursavus). The highest number of species (and genera) existed in Eurasia and North America during the Pliocene epoch. Best known are the cave bears, which lived in the Pleistocene epoch in Eurasia. Many ursids (six-seven genera) became extinct during the Anthropogenic period.
Some zoologists include the giant panda (Ailuropoda melanoleucd) among the ursids. Others regard them as a separate family or as part of the family Procyonidae (raccoons).
REFERENCESZhizn’ zhivotnykh. Vol. 5, Moscow 1941; vol. 6, Moscow, 1971.
Mlekopitaiushchie Sovetskogo Soiuza, vol. 2, part 1. Edited by V. G.Geptner and N. P. Naumov. Moscow, 1967.
Belyi medved’ i ego okhrana v Sovetskoi Arktike. Leningrad, 1969.
N. K. VERESHCHAGIN