The pitch and the duration of these sounds have meaning to other squirrels. Tail gestures are also a form of communication. Squirrels look like they run fast and for there size and weight they do. There is an old story of an Illinois state police officer that once clocked a gray squirrel, with his radar gun at 20 mph. Other research has confirmed similar speeds for squirrels.
Most squirrels eat nuts, seeds, and fruit.
By far their favorite food would be nuts, followed by sunflower seeds. Urban squirrel have adapted to eat just about anything, including pizza, luncheon meats and all forms of snack foods. Squirrels have been known to eat bird eggs, but this is a last resort. When natural food is scarce, they will eat anything they can find. Squirrels do fall, but they use their tail as a parachute and when they land their tail is used as a cushion.