It is a rich food source indeed, and these bears get bigger than any other brown bears. In northern inland areas, predation becomes more important. These bears are smaller but meaner than the big brownies of the coast. All grizzlies just love ground squirrels, above all the big groundhogs or marmots. A grizzly will think nothing of digging out two tons of dirt and gravel and moving sizeable boulders to get one of these toothsome furry morsels.
Grizzlies are as well-designed for digging as black bears are for climbing trees.
A bear's diet changes according to the time of the year too. In the spring, when they first awaken, they look for winter-kill to scavenge. Especially in tough northern climates, the bears will look for weakened, sickly hoofed animals or their new-born young to prey upon. The bears eat these industriously, but they don't have a lot of calories so the bears tend to slowly lose weight. Still, it helps to get them in shape for the rigors of mating season in the late spring.