Brown Bears are solitary, powerful predators who can be aggressive to one another. There is a social hierarchy: adult males are dominant, and females with cubs are dominant over juvenile males and females without cubs. Brown Bears are omnivorous, consuming everything from mosses, fungi, herbs, grasses, fruits, berries, small vertebrates, insects, birds, and fish especially salmon during their spawning run to other mammals. They dig after burrowing mammals and take down large hoofed mammals caught in deep snow or otherwise disabled. They are excellent swimmers and have acute senses of hearing and smell, but poor eyesight, and can attack humans without warning. The largest North American males weigh more than 600 kg (1,325 pounds).

Links:
Mammal Species of the World
Click here for The American Society of Mammalogists species account