Grizzly bears usually live as lone individuals, except for females accompanied by their cubs. Grizzly bears can be seen in close proximity in areas of abundant food, such as berry patches and salmon spawning areas. During the breeding season, a male may attend a female for up to two weeks for mating.
Grizzly bears are omnivorous, eating a mixed diet of grasses, berries, roots, fish and small mammals. They are also predators of caribou and moose and their calves. They will scavenge carrion when available. The roots of peavine (Hedysarum alpinum) are important spring and late fall food. Green vegetation is preferred through the summer. Berries, especially blueberries (Vaccinium uliginosum) and soapberries (Shepherdia canadensis) form the bulk of the diet starting in late July when grizzly bears go into a feeding frenzy called hyperphagia. During this time they eat nearly nonstop.
Female bears reach sexual maturity around six years of age. Mating usually occurs in June and July, with a pair coming together for one or two weeks and mating several times. With delayed implantation, cubs are born midwinter. A female can have one to three cubs which will stay with her for up to three and a half years.