naturalists Y oung ▼

Flying squirrels have special tools and tricks for living almost entirely in the treetops—and in the air.

by Christine Petersen

Nearly 300 years ago, a British explorer visited leaves, but that didn’t make sense because they appeared A flying squirrel colonial America. He was a naturalist named Mark to follow one another in one direction. glides through the Catesby, and as he traveled he kept a journal and It didn’t take Catesby long to solve the puzzle. What air from one tree to another. The sketched unfamiliar plants and animals he found along he had seen were tiny squirrels, “leaping from one Tree squirrels are most the way. One night, he watched several small objects fall to another.” Catesby watched with fascination as the active at night. from a tree. It was probably hard to see them in the dark creatures soared through the night like furry trapeze woods. At first, Catesby thought they were just falling artists. He called them flying squirrels. STAN TEKIELA

Minnesota Conservation Volunteer March–April 2019 45 STAN TEKIELA STAN TEKIELA STAN The northern flying squirrel, one of Minnesota’s two types, has a pale gray belly. The smaller southern flying squirrel, the state’s other species, often has a white belly. ID That Squirrel More than 40 flying squirrel species have the upper body is covered with brownish- dle-shaped leaves, and most of them keep which both species may share the same been identified around the world. Two gray fur that is as soft as velvet. their green needles all year. Deciduous patches of woodland. This region stretches of these—southern and northern flying trees have leaves that fall off seasonally from about Mille Lacs Lake to Wild River squirrels—live in Minnesota’s woodlands, Which one is it? Do you wonder which and later regrow. Spruce, fir, and hem- State Park. There, you must see a flying forests, and tree-filled city neighborhoods. flying squirrel lives in your neighbor- lock are important conifers for north- squirrel to identify its species. Flying squirrels avoid competing with hood? The answer depends on where ern flying squirrels in Minnesota. These Two traits can be used to tell the spe- other tree squirrels by being nocturnal. you are in Minnesota and the kinds of squirrels also use deciduous trees such as cies apart: size and the color of fur on They hide out by day and are active at trees that grow there. beech, maple, and birch. the animal’s belly. Southern flying squir- night, so they are very hard to spot. Northern flying squirrels often live in Southern flying squirrels can be found rels often have white belly fur, while the The two species of flying squirrels colder climates, from Alaska and Canada throughout the eastern United States, and northern species is pale gray beneath. look much alike. The head is small and to the northern United States, but also south into Mexico and Central America. Of the two, northern flying squirrels are rounded, with large, dark eyes and a pink in areas as far south as the Appalachian In Minnesota, they are most common in larger—about 12 inches long, includ- nose surrounded by long whiskers. Cup- Mountains. Minnesota’s northeastern Ar- the eastern counties—wherever there are ing the tail. That’s half the size of a gray shaped ears come to a sharp point at the rowhead region offers suitable habitat, with plenty of deciduous hardwood trees like squirrel. The southern species is about top. The flying squirrel’s tail is long and a mix of coniferous and deciduous trees. oak, beech, maple, and hickory. as big as a chipmunk, measuring just 9 fluffy but completely flat. In both species, Coniferous trees, or conifers, have nee- There is a small part of Minnesota in or 10 inches.

46 Minnesota Conservation Volunteer March–April 2019 47 A flying squirrel uses its rudder-like tail, padded feet, and long claws to land on a tree. Living Kites Back in the 1720s, when Mark Catesby unfold. Slender bones on the squirrel’s the few seconds it’s in the air. Kicking a landing against a tree trunk. Long, caught a flying squirrel, he was surprised feet extend to hold the membranes open. leg backward or slightly tilting its body curved claws grip the bark to prevent a to see that it didn’t have wings like a bat. The squirrel becomes a living kite, glid- causes a change in flight direction. The fall. Skittering around the tree and up- Instead, it has a membrane, or flap of ing gracefully through the night toward squirrel can angle its glide to avoid tree ward, the squirrel is ready to leap again. skin, between its legs. Biologists call this a distant tree. trunks and branches in its path. It can Most of the time, flying squirrels move membrane a patagium. The squirrel has swerve to escape a swooping owl or a between trees that are just dozens of feet two membranes—one on each side of its What goes up must come down. Grav- pouncing house cat. apart. But when conditions are right, they body. Together they are called patagia. ity is a natural force that pulls downward Landing requires skill. The squirrel can cover truly astounding distances. The The patagia usually rest loosely against on everything. So even with the aid of its raises its tail as it approaches the target known record is held by a northern flying the squirrel’s body like a furry cape. That gliding membranes, a flying squirrel be- tree. Like a furry rudder, the tail drags squirrel, which jumped down a moun- changes as soon as the squirrel jumps. gins to descend as soon as it jumps. But through the air and slows the glide. The tainside. It soared down the slope and

It stretches its legs wide and the patagia the animal has remarkable control for TEKIELA STAN animal’s padded feet soften its abrupt landed more than 290 feet away.

48 Minnesota Conservation Volunteer March–April 2019 49 Adapted for Gliding and Nocturnal Life Skull styliform cartilage is flexible. It spreads and holds patagium open and helps with steering northern flying squirrel Large eye sockets for (Glaucomys sabrinus) best night sight (10 to 15 inches)

patagium—a flap of skin that catches the air like a wing Large ear opening for better hearing and enables gliding

Front teeth southern flying squirrel Back teeth flat for strong and sharp grinding seeds for chewing through (Glaucomys volans) nut shells (8.3–10.2 inches)

Back leg with strong back claws for Nesting climbing trees Nest in tree crotch is called a drey

Long flat tail

Tree hole nest Diet Both species eat nuts, seeds, berries, fruits, fungi, lichen, tree buds, moths, beetles, insect larvae, spiders, bird eggs, small mice, shrews, and carrion (the flesh of dead animals). Both species also eat seeds at bird feeders. ILLUSTRATION BY TAINA LITWAK

50 51 Northern flying squirrels peek from their nest in an aspen tree in northern Minnesota. They huddle for warmth in winter. Home Sweet Home Northern flying squirrels often build nests family nest gets messy, mother squirrel high in conifer tree branches. From the can easily carry her babies to a fresh home. outside, a squirrel drey looks like a messy ball of twigs and leaves. Don’t be fooled. On the menu. Northern flying squirrels The drey is cleverly designed to keep its emerge soon after dark in search of food. owner safe, dry, and cozy. The squirrel The Arrowhead region gets a lot of snow. uses moss as insulation, stuffing it into the Mushrooms and lichens grow well in this cracks to block water and wind. It collects damp climate. Plant foods are also on the conifer needles, feathers, and fur to make a menu—from nuts and seeds to sap, fruit, soft bed inside the drey. and buds. Insects make a good snack, too. Northern flying squirrel mothers build The patagia make walking awkward large dreys, more than a foot wide, to hold and slow. But northern flying squirrels their growing babies. The southern species take the risk. The evidence can be found SUNDBERG PAUL prefers to live inside trees. These squirrels in winter. They leave long skidmarks in healthy. While carrying mushrooms to are usually family members, but a stranger may occupy an empty woodpecker hole or the snow where they land and run off to the nest, flying squirrels spread the spores is sometimes allowed to join. use a hollow space inside a decaying tree. dig their favorite mushrooms. from which more mushrooms grow. Even here in snowy Minnesota, fly- Southern flying squirrels will even nest in- In southern woodlands, flying squir- Where they nibble on tree buds, the plant ing squirrels don’t hibernate. They re- side buildings or take over bird boxes. rels eat a mix of plant and animal foods begins to sprout again. Uneaten nuts in main active even when temperatures This little squirrel’s ideal home has an mostly found in trees. They hunt June a squirrel’s cache can become new trees. fall below zero. Bad weather is a signal entrance roughly two inches across—you bugs and moths, pick berries and seeds, And flying squirrels eat many insects that to cuddle up and rest. The squirrels may could just slip a ping-pong ball through or take birds’ eggs and baby mice. Be- would otherwise damage the forest. go into torpor. In torpor, an animal’s it. Few predators are small enough to ginning in late summer, each south- heartbeat and breathing slow down. Its squeeze through such a narrow space. ern flying squirrel gathers hundreds What about winter? As winter ap- body saves energy. Each flying squirrel builds several nests of acorns and other nuts, then tucks proaches, northern flying squirrels move Sharing the nest also means the animals around its territory. These offer places to the food away in tree holes or cracks. from dreys into tree holes. Southern flying can share body heat, which is another way rest while feeding or to escape enemies. Throughout the long, harsh winter, it squirrels seek fresh nests, too. Each winter to save energy. One scientist found the The squirrel may even keep a special nest keeps coming back to this food cache. nest may contain eight or more individu- temperature inside a flying squirrel nest to use as a bathroom. And when an old Flying squirrels help the forest stay als together. The squirrels in a winter nest was about 36 degrees higher than outside.

52 Minnesota Conservation Volunteer March–April 2019 53 STAN TEKIELA STAN Baby flying squirrels are born blind and helpless but are ready to fly and leave their nest in two months. Family Life Flying squirrels emerge from the winter The warm season lasts longer in southern mammals, she produces milk that pro- mushrooms. By the age of two months, nest in early spring and begin to look for Minnesota. There, some flying squirrels vides all the nutrition her young need to young flying squirrels are as big as their mates. The mother squirrel gives birth are born in spring and others in summer. grow. Female squirrels are also ferocious- mother. They are ready to leave the nest. about five weeks after mating. Flying Newborn squirrels already have pata- ly territorial and may stamp their feet an- As the family explores the neighbor- squirrels usually have two to four babies, gia, evidence of the unusual lives they will grily at another squirrel or chase it away. hood, they cluck quietly or call out in high- which are blind and helpless at birth. lead. Within a week they begin to sprout When the babies are about 40 days old, pitched voices to stay in touch. Next time The newborns are pink and furless, ex- a coat of soft fur. But flying squirrels grow their mother brings solid food into the you’re outside at night, listen for these bird- cept for a brush of whiskers around the up slowly. Their eyes don’t open for about nest. The little ones have finally grown like sounds and watch for shadows leaping nose. They weigh up to 6 grams—about a month. The little animals can only sleep teeth. They get a first taste of soft food, among the trees. These secretive super- as much as six paperclips. or climb around inside the small nest as which might include fruit, soft insects, and squirrels might live in a tree near you. nV Summer is short in the Arrowhead re- they become stronger. gion. Northern flying squirrels usually Mother squirrel leaves the nest at night only have time to raise one litter of babies. and returns to nurse her babies. Like all Teachers resources. Find a Teachers Guide and other resources for this and other Young Naturalists stories at mndnr.gov/young_naturalists. 54 Minnesota Conservation Volunteer March–April 2019 55