Grizzly bears have been driven to extinction by indiscriminate hunting by humans, although they don't have any natural predators. It remains the only relative of the brown bear found in north America.
They are known to be solitude-loving animals that are seen in groups along river banks when salmon is in plenty. They love eating salmon which they can catch from the rivers. Summer is the breeding season for the salmons, and this is the time when they rush upstream for spawning. Grizzlies feast on the salmons that are a rich source of fat which is going to help them survive the hibernation in winter. Female grizzly bears are also seen with their cubs at times.
On an average, female grizzlies are supposed to live a longer life than their male counterparts. Males are known to have an average lifespan of 22 years, while females live to 26 years. The oldest known grizzly has lived in Alaska to 34 years, while grizzlies are known to have lived for about 44 years in captivity. All this is quite rare as most of them can't survive the first few years of their lives. They fall prey to depredation or hunting.
Grizzly bears spend 5-7 months every year in hibernation. Female grizzlies are known to bear progeny during this period. The baby grizzlies have only their mother's milk to feed on during this period. Male members of the species dig dens in the ground to prepare for hibernation. They consume a lot of salmon that deposits as fat around them. This fat is used during hibernation.