Gray squirrels make their home in middle and eastern United States, but have been introduced to the western United States and southern Canada. The squirrel is also found in the United Kingdom and parts of Ireland. This introduction endangers other types of squirrels and it is not clear how far the gray squirrel may spread, perhaps as far as Italy and South Africa.
As urbanization continues to spread and forests are cut down, more gray squirrels make their homes in cities. Squirrels live in trees throughout the entire year in either a small den area created by a woodpecker or a nest they build out of leaves. The green leaves make it practical during the summer months as they blend in with the foliage of the trees, but they tend to fall apart during winter. Some of the trees squirrels prefer are white oak, American beech, American elm, red maple and sweetgum.
The squirrels that inhabit a city tend to use bird feeders as a source of food. Others dig up flower bulbs and steal any garden vegetables they can find. Those who live in the forests collect food every day, even in winter. The squirrel is most active at dawn and dusk to avoid predators while collecting fruits, shoots and seeds. Its diet fluctuates with the season, with bark and fungi dominating in the winter and buds during the warmer months. A squirrel will raid a bird's nest for eggs if it is hungry enough. If a squirrel finds enough food, it buries the food near the surface.
Beyond the chance that a gray squirrel might end up as road kill, its main predator depends on its habitat. The main predators for the gray squirrels are hawks, owls, red foxes, raccoons and snakes. Mites are problematic as well, as they cause the squirrel to suffer an illness called mange, which makes its hair fall out.