There are two species of flying squirrels found in Pennsylvania. The northern flying squirrel makes its home in the northern conifer forests and is endangered, while the smaller Southern flying squirrel is found throughout Pennsylvania and is not endangered.

An extensive study in Pennsylvania found a population of only 33 northern squirrels. Most known sites are in the Pocono region, except for one in Warren County and one in Potter County.

While similar in appearance the southern flying squirrel is smaller with lighter colored fur that is tan to reddish-brown.

The best characteristic to distinguish the two species is the color of the belly fur between their front legs. If the fur is white, the squirrel is a southern flying squirrel. If the fur is white with gray fur near their skin, it is a northern flying squirrel.

A long history of the squirrel

In 1720 while exploring the forests of Pennsylvania a naturalist by the name of Mark Catesby was puzzled by the small creatures “flying” overhead.

He finally caught a flying squirrel expecting to find wings but what he found was that these small mammals have skin flaps that extend between the back and front legs, and a tail that is flattened top to bottom so they can steer when gliding from tree to tree.

The flying squirrel travels by gliding like a furry frisbee. They have been documented sailing up to 40 yards in a downward direction.

Where is home?

They are found in “mixed forests” favoring hickory, beech, oak, and poplar trees. The home range of these squirrels varies tremendously with them covering about 18 acres for the females and 20 acres for the males.

The reason for the males having a wider home range is to increase their chances of finding multiple mates. Nests can be found in dead or dying trees as well as woodpecker holes.

They also build nests out of leaves and twigs using them more for resting sites and are used during the summer, whereas cavities are used for breeding and raising young.

Tree cavities provide the best nest sites, but nests are built as well using bark, twigs, and roots and are lined with shredded strips of bark, moss, or lichens.

At different times of the year, fungi and lichens collected from trees or the ground are staple foodstuffs while other important foods are acorns, beechnuts, and seeds.

Unlike other species of tree squirrels, very few caches have been documented in either species of flying squirrels.

Most active during evening hours, flying squirrels may emerge briefly during the day. They are active year-round, foraging mainly in the treetops during the winter.

During severe cold, they may cluster together to keep warm.

Building a family

In Pennsylvania two litters are produced in mid- to late-May and again in September, with an average litter size of consisting of two young.

At six weeks of age, young leave the nest for short periods and begin to eat solid food and are weaned at about two months.

Young flying squirrels take their first “test flights” at about three months.

With their big eyes and sleek coats, they look like they would be docile but among tree squirrels they are the most predacious.

They will prey upon beetles, mice, moths, spiders, birds, eggs, mice, shrews, and carrion. They also are prey, and their predators include black rat snakes, owls, hawks, foxes, bobcats, weasels, and raccoons.

Southern squirrels

Southern flying squirrels are highly social mammals and have been observed flying and foraging together in large groups. They often den together, with as many as fifty individuals in one nest, as temperatures drop in order to conserve energy.

Research has shown that compared to individuals who nest alone in winter, squirrels nesting together conserve about 30% more energy. Although southern flying squirrels do show a preference for those who are related to them, they are tolerant of nonrelated individuals sharing nest sites.

So, all this information has me wondering … what species of flying squirrel is Bullwinkle’s friend “Rocky”?

Jeannie Carl is a naturalist at the Carbon County Environmental Education Center in Summit Hill. The center rehabilitates injured animals and educates the public on a variety of wildlife found in the area. For information on the Carbon County Environmental Center, visit www.carboneec.org.