Brown Bear (Ursus arctos): Facts, Grizzly Size and Habitat

What does a brown bear look like?

A brown bear is a big, heavily built bear with a broad head, a slightly concave or “dished” face, small rounded ears and a very short tail. Its most useful field mark is the shoulder hump, a mass of muscle above the front legs that powers digging. No other living bear has it.

Despite the name, coat color varies a lot. Brown bears can be cream, blond, reddish, chocolate or almost black, and many grizzlies have pale tips on their guard hairs that give them the “grizzled” look behind their common name. The front claws are long and only gently curved, typically 5–10 cm (2–4 in) along the curve, and often pale. They are made for digging roots and burrows rather than for climbing.

How big are brown bears?

The brown bear is the most variable in size of all bears. Bears with rich food, such as salmon on the coasts of Alaska and Kamchatka, grow much bigger than bears in dry mountains or on the Arctic tundra. Males are usually larger than females, often by a third or more, and every bear is heaviest in autumn and lightest when it leaves its winter den.

Head-and-body length ranges from about 1 to 2.8 m (3.3–9.2 ft), and shoulder height on all fours is roughly 0.9–1.5 m (3–5 ft). A large male standing on its hind legs can reach 2.5–3 m (8–10 ft). For the full story on weights and records, see how big do grizzly bears get?

Grizzly, Kodiak and other kinds of brown bear

All brown bears belong to one species, but people use different names for different populations. In North America, grizzly usually means inland bears, while bears along the coast of Alaska and British Columbia are called coastal brown bears. The Kodiak bear (U. a. middendorffi) lives only on the Kodiak Archipelago and has been isolated there since the end of the last Ice Age. In Europe and northern Asia the Eurasian brown bear (U. a. arctos) is the familiar form.

Scientists once described dozens of brown bear “species” and later as many as 90 subspecies. Genetic studies show that most of these are not distinct, and in North America the differences between grizzlies and coastal bears are mainly the result of diet and environment. The names are explained in is a grizzly a brown bear?

The brown bear’s closest living relative is the polar bear. The two species can interbreed, and wild grizzly–polar bear hybrids have been confirmed in the Canadian Arctic since 2006.

Habitat and range

Brown bears use more kinds of habitat than any other bear: northern forests, mountain slopes and alpine meadows, Arctic tundra, steppe and coastal river valleys, from sea level to about 5,000 m (16,000 ft) in the Himalayas. Many prefer semi-open country with thick cover nearby for resting.

The global population is estimated at about 200,000 bears. Russia holds the largest number, well over 100,000. In North America, about 30,000 live in Alaska and about 25,000 in western Canada, while the contiguous United States has roughly 2,000 grizzlies, mainly around Yellowstone and in northwestern Montana, with small numbers in Idaho and Washington.

Europe outside Russia has about 17,000 brown bears in several separate populations, with strongholds in the Carpathian Mountains (especially Romania), Scandinavia and Finland, and the Dinaric Mountains of the Balkans. Smaller populations survive in the Alps, the Apennines of Italy, the Pyrenees and the Cantabrian Mountains of Spain. Bears disappeared long ago from Britain, the Netherlands and Denmark, and in the 19th and early 20th centuries from California, Mexico and the Atlas Mountains of North Africa.

What do brown bears eat?

Brown bears are omnivores, and for many of them plants supply most of the energy in their diet, in some populations up to about 90%. They eat grasses, sedges, roots, bulbs, berries, nuts, acorns and fungi, digging with their long claws and powerful shoulders.

Animal food depends on what is available. Coastal bears in Alaska fatten on spawning salmon, and in Katmai National Park dozens of bears gather at Brooks Falls to catch fish. Bears in Yellowstone eat whitebark pine nuts and dig up army cutworm moths on high talus slopes, sometimes eating tens of thousands of moths in a day. Elsewhere bears dig out ground squirrels and marmots, raid ant nests and beehives, scavenge winter-killed carcasses and prey on newborn elk, moose and caribou calves in early summer. More detail is in what do brown bears eat?

In late summer and autumn, bears enter a phase called hyperphagia, eating almost nonstop to build fat. A large bear can gain up to about 180 kg (400 lb) between spring and autumn.

Behavior and winter denning

Brown bears are mostly solitary. Adults meet when mating, and mothers stay with their cubs, but bears can tolerate each other at rich food sources such as salmon streams, where they form a pecking order based on size and age. They are not strictly territorial and roam large home ranges, from about 24 km² (9 sq mi) for females on rich Alaskan coasts to several thousand square kilometers for males in the Canadian Arctic.

Bears communicate with body posture, huffs, woofs, jaw popping, growls and scent marks, and they often rub against “bear trees”. Their sense of smell is excellent, and their brain is large for a carnivore of their size.

In autumn most brown bears dig a den in a hillside, under tree roots or in a cave, and spend the winter inside for roughly four to seven months in cold regions, living on stored fat without eating, drinking or passing waste. Their body temperature falls only a few degrees, and they can wake quickly. In mild areas with food all year, some bears hardly den at all.

Reproduction and life cycle

Mating takes place from about mid-May to July. The fertilized egg does not implant in the womb until late autumn, a process called delayed implantation, and if the female has not stored enough fat, the pregnancy does not continue. Cubs are born in the den in January or February while the mother rests.

Litters usually have one to three cubs, rarely up to four or more. Newborn cubs weigh only about 340–680 g (12–24 oz) and are blind and almost naked. They leave the den in spring and stay with their mother for about 1.5 to 4.5 years, learning where and how to find food. Females usually breed every three to four years and have their first cubs at around four to eight years old, which makes brown bears one of the slowest-breeding land mammals in North America.

Lifespan, predators and threats

Wild brown bears often live 20–30 years where they are not heavily hunted, and the oldest known wild bear was nearly 37. In captivity they have lived to about 50. Many cubs die in their first year, from starvation, accidents or killing by adult male bears.

Adults have few natural enemies apart from other bears and, in the Russian Far East, Siberian tigers. The main threats are people: habitat loss and fragmentation, road and rail collisions, conflict over livestock and beehives, poaching and overhunting in some regions.

Conservation status

The IUCN Red List classifies the brown bear as Least Concern with a stable population trend (assessment published in 2017). That global picture hides big regional differences. Bears in Alaska, Canada, Russia and northern Europe are numerous, but several isolated populations are small. The Marsican brown bear of central Italy numbers only about 50–60 animals, and the Himalayan brown bear survives in a tiny fraction of its former range.

In the contiguous United States, grizzlies have been listed as threatened under the Endangered Species Act since 1975. The Yellowstone population grew from about 136 bears in 1975 to around 1,000 today. In Europe, protection under the Habitats Directive helped bears return to parts of the Alps and Pyrenees, partly through releases of bears from Slovenia.

Brown bears and people

Brown bears usually avoid people, and attacks are rare, but they can be dangerous when surprised at close range, when defending cubs or a carcass, or when they have learned to find human food. Mothers with cubs cause most serious incidents in North America. Read the evidence in are bears dangerous?

The bear also has a huge cultural role. It appears in Paleolithic cave art, Native American traditions and European folklore, and it is Finland’s national animal. A grizzly is on California’s state flag, although the state’s last grizzlies were killed in the 1920s.

Myths and facts

• Myth: brown bears are mainly meat-eaters. Fact: most brown bears get the bulk of their energy from plants, insects and fish; hunting large animals is a small part of the diet for many bears.
• Myth: color tells you the species. Fact: brown bears can look almost black, and American black bears are often brown, so use the shoulder hump, face profile and ears instead; see grizzly bear vs black bear.
• Myth: bears sleep all winter without waking. Fact: denning bears can wake and move quickly, and some leave their dens during mild spells.