The gray squirrel is, essentially, a forest animal, but it has adapted well to different environments.
It can cross waters and marshlands and swim rivers.
Gray squirrels can be found in urban areas - wherever there are trees, bushes or hedges.
Squirrels have become so familiar with humans that they can sometimes be hand fed.
Some people have kept gray squirrels as pets.
The gray squirrel has a short, sleek summer coat. It is usually brownish gray on top. There is a chestnut streak on the squirrel's flanks and feet and often on the outer edges of its limbs.
Its tail hairs are thin and have an indistinct white fringe.
In the winter, the coat is thicker. It is silver gray on top, with yellowish brown fur on the squirrel's head and along its flanks. The squirrel's belly is white, and its legs and feet are gray.
The big, bushy tail is dark gray with a white fringe.
There are variations in color. Some squirrels are black (melanistic). Some have reddish brown backs and can be mistaken for red squirrels. Some are albino.
The squirrel's large eyes are set in the side of the head, allowing it to see at a wide angle.
The diet of the gray squirrel is extremely varied.
It includes insects, young birds and bird's eggs as well as farm crops, such as wheat, barley and oats.
Like all rodents, the gray squirrel has incisors (front teeth) that must constantly be trimmed. The squirrel attends to this need by gnawing on nuts and seeds continually.
Sometimes, the squirrel will eat its food as soon as it finds it.
At other times, it will carry its food to a safe eating place, where it can keep an eye on its surroundings.
This may be somewhere high in the trees or on a fence post or tree stump,
If it is very hot or too cold, the gray squirrel will stay in its drey (nest).
However, it cannot go for more than two or three days without food, and if necessary will leave the drey to find food even when the weather is bad.
From late summer through autumn, the gray squirrel establishes caches for its food, so that it is available to eat during the winter.
Any nuts that are not retrieved by the squirrel in winter will often sprout, becoming new trees.
The gray squirrel is extremely agile and easily run up and down tree trunks.
It can balance on thin twigs.
It uses its large tail for balance when leaping from branch to branch and from tree to tree.
On the ground, the gray squirrel can move as fast as 20 miles per hour, moving in short leaps or runs. It holds its tail out straight behind as it runs.
It will pauses frequently to observe its surroundings, sitting upright on its hind feet with its tail flat along the ground, sniffing the air and holding its and its ears erect.
The squirrel swims with its head and tail above the water. It holds it tail up so that it acts like a sail.
The gray squirrel has two mating seasons. The first is in May and the second in December.
During courtship, males engage in displays. A number of males will sometimes chase after a female just before mating time.
After mating, the female drives the male from the tree and then builds the drey in which she will give birth.
Sometimes she will enlarge an older drey or make a den in a hole in the tree. She may take over an old woodpecker nest.
The young squirrels begin wandering outside the drey when they are ten weeks old.
In another three week, they leave permanently.
The female then prepares for her next litter.
Young female squirrels are can breed six or seven months after they are born. They usually breed by the time they are a year old.