One of the smaller-bodied forms, the Himalayan brown bear, is critically endangered: it occupies only 2% of its former range and is threatened by uncontrolled poaching for its body parts.

This name originated in the fable History of Reynard the Fox, translated by William Caxton, from the Middle Dutch word bruun or bruyn, meaning "brown".

[30] Genetic evidence suggests that several brown bear populations migrated into North America, aligning with the glacial cycles of the Pleistocene.

[30] Brown-bear fossils discovered in Ontario, Ohio, Kentucky, and Labrador show that the species occurred farther east than indicated in historic records.

Brown bears live in Alaska, east through the Yukon and Northwest Territories, south through British Columbia, and through the western half of Alberta.

[55] While the brown bear's range has shrunk and it has faced local extinctions, it remains listed as a least-concern species by the IUCN, with a total population of approximately 200,000.

[67] One of the smallest-bodied subspecies, the Himalayan brown bear (U. a. isabellinus), is critically endangered: it occupies only 2% of its former range and is threatened by uncontrolled poaching for its body parts.

[70] In one instance, a 3-year-long survey in the Russian Far East detected the illegal shipping of brown bear gallbladders to Southeast Asian countries.

[71] An action plan in 2000 aimed to conserve brown bears in Europe by mitigating human–wildlife conflict, educating farm owners as to sustainable practices, and preserving and expanding remaining forests.

[79][80] From summer through autumn, a brown bear can double its weight from what it was in the spring, gaining up to 180 kg (400 lb) of fat, on which it relies to make it through winter, when it becomes lethargic.

[83] Hibernation dens may be located at any spot that provides cover from the elements and that can accommodate their bodies, such as a cave, crevice, cavernous tree roots, or hollow logs.

[84] Brown bears have one of the largest brains of any extant carnivoran relative to their body size and have been shown to engage in tool use, which requires advanced cognitive abilities.

[85] This species is mostly solitary, although bears may gather in large numbers at major food sources (e.g., open garbage dumps or rivers containing spawning salmon) and form social hierarchies based on age and size.

When approached by another individual, the animal makes a "puckered-lip face" with a protruding upper lip and ears that go from cocked and alert when at a certain distance to laid back when closer or when retreating.

Several adult bears roam freely over the same vicinity without contention, unless rights to a fertile female or food sources are being contested.

At this time, the cubs weigh 7 to 9 kg (15 to 20 lb) and have developed enough to follow and forage for solid food with their mother over long distances.

During the dependency stage, the cubs learn (rather than inherit as instincts from birth) survival techniques, such as which foods have the highest nutritional value and where to obtain them; how to hunt, fish, and defend themselves; and where to den.

[94] Increased brain size in large carnivores has been positively linked to whether a given species is solitary, as is the brown bear, or raises offspring communally.

[33] In spring, winter-provided carrion, grasses, shoots, sedges, moss,[116] and forbs are the dietary mainstays for brown bears internationally.

[55] They will also commonly consume animal matter, which in summer and autumn may regularly be in the form of insects, larvae, and grubs, including beehives.

[48] The diet may be supplemented by rodents or similar small mammals, including marmots, ground squirrels, mice, rats, lemmings, and voles.

[33] With particular regularity, bears in Denali National Park will wait at burrows of Arctic ground squirrels, hoping to pick off a few of those 1 kg (2.2 lb) rodents.

[33] Plants and fruit farmed by humans are readily consumed as well, including corn, wheat, sorghum, melons, and any form of berries.

In the same time period, four cases of brown bears killing female tigers and young cubs were reported, both in disputes over prey and in self-defense.

One major finding was that the presence of the plasma protein sex hormone-binding globulin (SHBG) increased by 45 times during the brown bear's hibernation period.

The image of the mother bear was prevalent throughout societies in North America and Eurasia, based on the female's devotion and protection of her cubs.

In German-speaking countries, children are often told the fairytale of "Snow White and Rose Red"; the handsome prince in this tale has been transfigured into a brown bear.

In addition, community members that wore bear claw necklaces were highly respected, as wearing one was seen as a sign of bravery and honor.

In many western stories and older fables the portrayed attributes of bears are sluggishness, foolishness, and gullibility, which contradicts the actual behavior of the species.

[174] The coat of arms of Madrid depicts a bear reaching up into a madroño or strawberry tree (Arbutus unedo) to eat some of its fruit.