Grey squirrels, or Eastern grey squirrels, primarily live in the Eastern half of the U.S. and southern Canada. There is also a healthy population in the U.K., where they were imported in the 19th century. Grey squirrels are equally at home in urban and rural areas. They are commonly found in yards, parks, and gardens.
Some people believe grey squirrels hibernate because they are seldom seen during the colder months. However, grey squirrels remain active all year. They are most active in the hours just after dawn and before dusk. During periods of extreme cold, they may snuggle up in their dens or nests for several days. So, how do squirrels make it through the winter? Keep reading to find out.

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Grey Squirrels Don’t Need to Hibernate
It is often assumed that grey squirrels hibernate during the winter months. However, grey squirrels do not need to hibernate because they are homeotherms. This means their body temperature stays fairly consistent regardless of the outside temperature. They have also adopted several techniques that help them survive through the colder months.
When the seasons change from summer to autumn, grey squirrels forage for food. They collect seeds, nuts, and berries which are buried underground or stored in holes in the trees. Grey squirrels have a largely vegetarian diet. However, when food is in short supply, they may prey on small birds or steal eggs to survive.
Bulking Up and Hunkering Down
The grey squirrel’s yellow-brown summer coat grows thicker and turns a silvery-grey color. They also eat large amounts of food to bulk up for the winter. Some scientists believe grey squirrels increase their weight by as much as 25%. These fat stores help the squirrel stay warm. Another strategy squirrels use to keep warm is shivering. Just like with humans, the rapid muscle contractions of shivering generate heat.
Grey squirrels prefer to make a den in a tree cavity to stay in during the winter. They may even share a den with other squirrels to stay warm. If more permanent housing is unavailable, they may take shelter in a nest, or drey. Dreys are built from leaves and branches with softer materials like moss in the innermost layers. These structures are located high up in the trees, either near the trunk or the junction of two large branches for stability.

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Squirrel Courtship
Squirrel courtship and breeding also take place during the winter. Squirrels have two breeding periods, one in December-February and another in May-June. Males commonly compete to mate with a single female. The gestation period for a grey squirrel is 44 days. The female typically gives birth to 2-4 babies.
Grey squirrels don’t hibernate, but they don’t need to. They are champions at planning ahead and they have plenty of ways to stay warm in the cold. They’re also far too busy trying to keep their species going to take a long winter’s nap.
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