Adult bears are solitary except during the mating season. Groups may feed together where quantities of food are available, but there is little social contact. In cold climates bears sleep through most of the winter in individual dens made in caves or holes in the ground. This sleep is not a true hibernation, as the bear's metabolism remains in a normal state and it may wake and emerge during warm spells. The young, usually twins, are born during winter in a very immature state. Cubs stay with their mothers for about a year, and females usually mate only every other year. Bears are not generally subject to predation, unless they are in a weakened condition. A bear is a formidable adversary and may attack a human if it is injured or startled.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.