Brown bears were larger, powerful Bears that inhabited forests, river valleys, and mountainous regions. They had thick fur ranging from light brown to deep chocolate, strong limbs, and massive paws tipped with long claws. Adult males measured 2–2.8 m (6.5–9 ft) in length and weighed 180–450 kg (400–1,000 lb), while females were slightly smaller.
Brown bears were omnivorous, feeding on a wide variety of plants, berries, roots, insects, fish, and small mammals. They were solitary foragers, roaming vast territories in search of food. Some populations specialized in hunting fish during seasonal runs, while others relied heavily on plant matter. They had keen senses of smell and hearing, allowing them to detect prey or edible plants from a great distance.
During colder seasons, brown bears retreated to dens for extended periods of rest. Mothers raised one to three cubs in these dens, protecting them fiercely. Though generally non-confrontational, brown bears could be aggressive when surprised, defending cubs, or competing over rich food sources.