With a population double that of all other bear species combined, the American black bear is by far the most common member of the bear family (Ursidae). Despite its common name, the black bear exhibits considerable variation in colouration, both among individuals from a single litter, and between populations from separate geographical regions. While most populations in the west of the American black bear’s range have black fur, in the east, many populations have lighter cinnamon or yellow-brown coats. In addition, some populations found along the pacific coast have grey-blue fur, while in British Columbia, Canada, around ten percent of the population have an entirely white coat. It has been suggested that the variability in coat colouration may be related to habitat, with lighter coloured bears occurring in open habitats. It may also serve a purpose in mimicking brown bears (Ursus arctos) that compete and sometimes prey upon this species. Despite some similarities between the American black bear and the brown bear, this species can readily be identified by its head profile, which slopes in a roughly straight line from the brow to the end of the snout. In addition, it lacks a prominent shoulder hump, and has short claws, well suited for climbing. The American black bear produces a range of vocalizations, with a “woof” sound usually given in alarm by adults, while the young may produce shrill howls when lonely or frightened.