In a few areas they are known to be predators of larger animals such as caribou and moose. They will also scavenge carrion when available, including whale, walrus and seals that have washed up on shore. Brown bears are solitary animals except for females with cubs. They are territorial with males having larger territories overlapping the smaller territories of several females. Brown bears can be seen in close proximity in areas of extremely abundant food sources, such as dumps sites, berry patches and salmon spawning areas.
Female bears reach sexual maturity around four and a half years of age.
Mating will occur between May and July, with a pair coming together for one or two weeks and mating several times. With delayed implantation, cubs are born between January and March. A female can have up to four cubs which will stay with her for up to two and a half years. They are also listed in the lower 48 states as a threatened species under the Endangered Species Act with the US Fish and Wildlife Service. Brown bears in some areas live in isolated pockets of land, all subject to extreme human encroachment and ensuing habitat loss.