Distinguishing between black bears (Ursus americanus) and brown bears (Ursus arctos) involves more than just their names. While color can be misleading, specific physical characteristics and average sizes provide clearer distinctions.
Comparing Bear Sizes
Brown bears are generally larger and heavier than black bears. Male brown bears typically weigh between 80 to 600 kg (180 to 1,320 lb), with a head-and-body length of 1.4 to 2.8 meters (4 ft 7 in to 9 ft 2 in) and a shoulder height of 70 to 153 cm (28 to 60 in). In contrast, adult male black bears typically weigh between 57–250 kg (126–551 lb), with a head-and-body length of 1.2 to 2.1 meters (4 to 6 ft 8 in) and a shoulder height of 70 to 105 cm (28 to 41 in). Female bears of both species are typically smaller than males.
While brown bears are usually larger, individual variation exists. A large male black bear can sometimes be comparable in size to a smaller female brown bear or a juvenile brown bear. For example, some black bears have been recorded weighing up to 400 kg (880 lbs). Despite these overlaps, the typical brown bear significantly outweighs and outmeasures the typical black bear.
Identifying Features Beyond Size
Since size is variable and difficult to assess in the wild, other physical characteristics reliably distinguish black bears from brown bears. A prominent muscular hump on a brown bear’s shoulders is a key distinguishing feature, absent in black bears. This hump is composed of muscle used for digging. When standing on all fours, a brown bear’s highest point is its shoulder hump, while a black bear’s rump is typically higher than its shoulders.
Facial structure also provides clues. Brown bears have a “dished” or concave facial profile, with a noticeably blunter nose that drops from their forehead. Black bears, in contrast, have a straighter facial profile, sometimes described as dog-like. Their ears also differ: black bears have taller, more pointed ears, while brown bears possess shorter, rounder ears that blend into their head fur. Additionally, brown bears have long, straighter claws, ideal for digging, while black bears have shorter, more curved claws better suited for climbing trees.
Factors Influencing Bear Size
Bear size varies due to several environmental and biological factors. Diet plays a significant role; bears with access to abundant, high-calorie food sources, such as salmon, tend to be larger. Habitat quality and geographic location also influence size, with bears in richer environments typically growing bigger. Age is another factor, as bears continue to grow for several years, with males reaching their maximum weight later than females.
Brown bear subspecies further illustrate size variation. Grizzly bears (Ursus arctos horribilis), a North American brown bear subspecies, are generally smaller than coastal brown bears, but still larger than black bears. Kodiak bears (Ursus arctos middendorffi), found exclusively on the Kodiak Archipelago in Alaska, are among the largest brown bears, with males weighing up to 720 kg (1,600 pounds). These bears highlight the significant size range within the brown bear species, often exceeding any black bear’s size.