Ursus arctos

Color ranges from pale yellowish to dark brown; usually white tips on the hairs, especially on the back, resulting in a frosted or grizzled effect; facial profile concave; claws on front feet of adults about 4 inches long and curved; noticeable hump above shoulders; head and body of adults about 6-8 feet, height at shoulders 3-4.5 feet (Burt and Grossenheider 1964).

Differs from black bear in being larger as an adult and by having a hump above the shoulders and a concave (rather than straight or convex) facial profile.

Now found mostly in arctic tundra, alpine tundra, and subalpine mountain forests. Once found in a wide variety of habitats including: open prairie, brushlands, riparian woodlands, and semidesert scrub. Ranges widely at the landscape level. Most populations require huge areas of suitable habitat. Common only where food is abundant and concentrated (e.g., salmon runs, caribou calving grounds). Typically digs own hibernation den, usually on steep northern slope where snow accumulates. See LeFranc et al. (1987).

Young are born in den in cave, crevice, hollow tree, hollow dug under rock, or similar site. Use of summit or ridge for mating (in May-June) reported for Banff National Park, Alberta, but not elsewhere (Hamer and Herrero 1990). In the Northwest Territories, Canada, all dens were on well-drained slopes; the majority of dens faced south (25), followed by west (13), east (10), and north (8); most dens were constructed under cover of tall shrubs (Betula glandulosa and Salix), the root structures of which supported ceilings of dens; esker habitat was selected more than expected by chance (McLoughlin et al. 2002).

In Spain, remnant deciduous forests and upland creek drainages were prime feeding areas (Clevenger et al. 1992).

May congregate in areas with abundant food; otherwise solitary except when breeding or caring for young. Density estimates range from 1/1.5-4 sq km (Kodiak Island) to 1/50 sq km (Yellowstone) to 0.6-7.9/1000 sq km (Norway).

In the Yellowstone region, lack of berries and large fluctuations in the size of pine seed crops were major factors limiting bear density (Mattson et al. 1991).

In British Columbia-Montana, survivorship of adult and subadult females was the most important variable in estimating population trend.

Breeds in late spring and early summer. Implantation is delayed; gestation lasts about 184 days. Litter size is 1-4 (average 2). Young are born in winter, remain with mother usually the first two winters. Breeding interval generally is 2-4 years. In North America, first parturition occurs at 5-6 years in the south, 6-9 years in the north. A few live as long as 20-25 years. Long life span, late sexual maturity, protracted reproductive cycles.