While the American black bear typically forages during the night, it is potentially active at any time (4). Feeding is opportunistic, with a wide variety of foods taken according to location and season (2). In some parts of this species’ range, as much as 95 percent of the diet may consist of plant-based foods, such as roots, buds, berries, nuts and fruits (5). Animals may also be taken, particularly by American black bear populations found in Labrador, which hunt small mammals and caribou (2). Due to the proximity of human settlements to many parts of this species’ range, as well as increasing recreational use of its habitat, the American black bear has adapted to exploit a variety of human-related foods. These include refuse, birdseed, agricultural products and honey from apiaries (1) Despite this bear’s typically slow-moving, lumbering gait, it can move at great speed when necessary, and is capable of climbing trees and swimming (4). Home ranges are large, and vary according to the geographical area. Males on Long Island, off south-western Washington, range over areas of around 5 square kilometres, while males found in the tundra of the Ungava Peninsula, Canada range over areas of up to 1,000 square kilometres (4). While home ranges may overlap, this species is generally solitary, and at certain times of the year may be territorial. Congregations do occur around abundant food sources, at which time dominance hierarchies form (4).
While breeding occurs between June and July, the fertilised eggs undergo delayed development and do not implant in the female’s womb until November. Thereafter they undergo a rapid ten week development, with a litter of up to six cubs being born around January (2). Despite being weaned at six to eight months old, the cubs remain with the mother for a further 9 months, spending a second winter in hibernation together, before separating to avoid male aggression during the breeding season (2) (4). Reproductive maturity is reached at around four to five years in females and a year later in males, while the lifespan is usually 25 years (2) (4).
In the northern parts of its range, the American black bear undergoes an annual period of hibernation, during which it lives on stored fat, and reduces its body temperature and heart-rate to conserve energy (2) (4). In the warmer southern parts of its range, this species may hibernate for much shorter periods or remain active all year round, although pregnant females always create a den in which to spend the winter, give birth and nurse the cubs. Dens are usually constructed by digging out a hollow in earth or snow, although in southern regions dens may also be built in trees (2).