Squirrels can eat 1 pound of food per week (1.5 to 3 ounces a day) and drink roughly 2 to 3 tablespoons of water each day. They spread their nut caches over an area larger than 2 square miles. The diet of most squirrels consists of berries, leaves, seeds, fungi, buds, shoots, flowers, nuts and bark. Of course, they’ll eat smaller rodents, bird’s eggs, insects and nestlings if they are super hungry.
In fact, squirrels spend the majority of their day eating, gathering and storing food. However, urban squirrels will eat anything — bread, candy, popcorn or whatever they can find on the ground, including leftover food from humans.
Fun side note: I once saw a squirrel carry an entire loaf of white bread up a tree to his nest!