There are five species of squirrels found in the state of Wisconsin: gray, fox, red, and southern and northern flying squirrels. All are very visible and very abundant in our area, except for the nocturnal flying squirrels that are rarely seen.
Squirrels can be cute to watch, but can also be responsible for stripping bark off trees, raiding gardens and bird feeders, gnawing on siding, and invading homes. They are very destructive, and once inside an attic or crawlspace they will use insulation to create a nest and are known for chewing the insulation off wiring and causing fire hazards.
These are the most common tree squirrels in Wisconsin. They’re approximately 18-21 inches long, including their 8-10 inch tail. They build nests in tree branches or inside hollow trunks, and may even use empty birds’ nests. They feed on acorns, hickory nuts and walnuts and will even nibble on corn, berries, apples and sap. They do not hibernate and are most active at dawn and dusk and throughout the daytime hours when they search for food. They have two litters per year: the first near the end of February and the second in July or August. The average litter size is four, but can range anywhere between two and eight.
Fox squirrels are the largest tree squirrels native to North America, are the largest in Wisconsin (20-22 inches in length) and found in the southern part of the state. Many times they’re mistaken for a gray squirrel, but they’re larger with a coat coloring that matches that of a fox. They spend a lot of time on the ground, aren’t well-adapted to the urban areas but can be just as detrimental as grey squirrels. They are also active during daytime hours (8 am to 5 pm) and eat a similar diet to the grey squirrel with the addition of gourds, bulbs, insects and bird eggs. They have two litters per year: the first between February – March, and the second between July – August. The average litter size ranges between two and four, with the average being three.
Red squirrels are quite small, only 11 to 14” long including a 4 to 6” tail. They are reddish to reddish-gray on top with a white or cream underside, and a white area around their eyes. Their tails are not as long or bushy as those of other tree squirrels. They mainly eat pine seeds, but will eat other nuts, berries and mushrooms, and may drink sap from maple trees. They’re very solitary animals, with moms and babies staying together for only the first 10 weeks of life. They have two litters per year: the first in February/March, and the second between July and August. Their litter size is usually between two and six, with the average being four.
The northern and southern flying squirrels are active during night time hours (nocturnal) and are the smallest squirrels found in Wisconsin. The northern is slightly larger (10-13”) than the southern (8-10”) and both are small and light brown, with the northern being slightly redder on the upper body. Flying squirrels don’t actually fly; they glide from a higher point to a lower point with a flap of skin that extends from their wrist to their ankle. They can glide for up to 150 feet and readily eat nuts, seeds, berries and insects. Both varieties have litter quantities between two and six, with the average being three. The northern variety has only one litter per year in April/May, while the southern has two: in February/March, and again between May and July.
Flying squirrels are very shy animals and don’t cause as much damage as grey and red squirrels, but they can be found in attics, vacant cabins and walls. They are also communal dwellers and are usually found with a large number of their kind in whatever space they choose for their winter dwelling.