The lifespan of the gray squirrel varies, but they can live up to 10 years in the wild.
Squirrels’ home ranges are generally only a few acres, so it’s possible that you are seeing the same squirrel families year after year. Try to pick out distinguishing characteristics (ear notches, color variation, etc.) to follow individual squirrels!
The species that we commonly call the eastern gray squirrel was, according to historical documents, originally mostly black. One historical account says:
Grey-squirrels were rarely met with before the commencement of the [20th] century, though they are now quite numerous; while black-squirrels, though now nearly if not quite extinct, were then found in large numbers.
For further discussion see this resource.
You may have noticed squirrels making many different sounds like squeaks, chatters, and raspy, scolding noises. They are using these sounds to communicate with each other! Squirrels make different sounds to communicate territoriality, alarm and courtship. Squirrels also communicate by flicking their tails in different ways.
Gray squirrels build nests, called dreys, out of sticks and leaves. You can see these in the tops of trees in the fall and winter. Dreys are about the size of basketballs. These are "communal nests" that several squirrels usually occupy at the same time. Only pregnant females like to be alone in their own nest; otherwise it’s warmer in a shared nest. Squirrels will spend the majority of the winter in the drey, coming out occasionally to search for food that they have buried or to bask on a sunny day. In the drey, a squirrel will cover itself with its big, furry tail to stay warm. Squirrels keep their activities to a minimum to conserve energy, which isn’t true hibernation (like a bear).