BEAR

American black bear (Ursus americanus) large carnivore of the family Ursidae, closely related to the dog (family Canidae) and raccoon (Procyonidae). The bear is the most recently evolved of carnivores. Its ancestral line appears to have diverged from canid stock during the Miocene and to have developed, through such forms as the Pliocene Hyaenarctos (of Europe, Asia, and North America), into modern types such as the black (see photograph) and brown bear (Ursus). Generally massive and short legged, bears vary in size from the smallest sun bear (27-46 kilograms [59-80 pounds]) to the huge Alaskan brown bear (see grizzly bear), which attains a weight of 780 kg. Despite this bulkiness, most bears climb with ease and swim strongly. They walk with their soles on the ground in plantigrade fashion, as does man, with the heel touching the ground. Each foot has five digits, ending in nonretractile claws (sometimes particularly adapted for digging, as in the sloth bear). Lengthening of the canine teeth, reduction or absence of the first three premolars, and modifications for crushing with the molars (broad and flat crowned) characterize ursid dentition, completed with typical incisors. Bears constitute a generally omnivorous family, but individual dietary preferences range from seals for the extremely carnivorous polar bear to vegetative materials for the largely herbivorous spectacled bear; most bears enjoy honey. Usually gaining weight beforehand, a bear often sleeps fitfully through much of the winter; this long slumber, however, does not constitute true hibernation. Bears in the wild live from 15 to 30 years. The life span in captivity is considerably longer. The bear may be hunted for trophy value or for its various economic assets, hides for clothes or rugs and meat and fat for food. Local names, derived particularly from their geographic locations, abound for these bears (see Table).