Creature Feature: Flying Squirrels by David Heithaus, was originally published in the BFEC Newsletter, Vol. 17/No. 4, Fall 2013.
Name: The species' scientific name Glaucomys volans translates to "blue-grey mouse-like flying creature."
Size: Adults are generally 8-10 inches long including a 3-4 inch tail. They weigh only 2-4 ounces.
Life span: Up to 13 years in captivity but probably only 5-6 years in the wild.
Diet: Diverse! Insects, nestlings, eggs, nuts, seeds, fruit, bark, fungi, lichens, sap, mice and even carrion.
Predators: Owls, raccoons, snakes, domestic dogs and cats.
Activity: Nocturnal.
Range: All of Ohio, year-round residents.
Reproduction: Mate April-May and August-September with 2-6 young born about 40 days later.
Fun fact: As cute and cuddly as they may appear, flying squirrels are considered more blood thirsty than other squirrels with other critters forming a larger percentage of their diets. Not unlike the Donner Party, carrion gets popular during winter months.
Aliases: Southern flying squirrels carry a number of local handles throughout their extensive range. Depending on who you ask (and in what language) they are called the Eastern flying squirrel, white-furred flying squirrel, fairy diddle, fairy glider, petite polatouche, assapanick or ardila voladora de sur.
If someone were to ask you what the most common squirrel in Ohio was, you'd probably conjure a vision of something big and gray and bushy-tailed. Fair enough; it's hard to walk fifty steps in Gambier without being accosted by a gray squirrel with a Snickers wrapper. In reality though, our most plentiful squirrels may be ones you've never seen before: southern flying squirrels. Really. We are just lousy with southern flying squirrels.
But how can that be, you may wonder. Are they microscopic? Do they live under water? Are they transdimensional like Bigfoot ("Ohio Grassman," scientific name still debated)? Not at all, they are simply... nocturnal.
Like the chupacabra. Or maybe more like Batman with the gliding and all.
While there are over 30 species of flying squirrel world-wide, only two inhabit North America: the Southern flying squirrel (Glaucomys volans) and its slightly larger cousin the Northern flying squirrel (Glaucomys sabrinus). Only the Southern flying squirrel can be found in Ohio.
Southern flying squirrels are small and lightly built. Seldom do they exceed 10 inches in overall length or 4 ounces in weight. More often they are 8.5 to 9.5 inches long and only 2 to 3 ounces. They range in color from reddish brown to gray with a cream-colored belly. Their gliding membrane, or patagium, runs along their sides between their fore- and hind-limbs and is fringed with black fur. Flying squirrels have large eyes to serve their nocturnal lifestyle and a flattened tail that acts as a stabilizer during "flight."
They are "Southern" only relative to their cousins who prefer arboreal forests and range as far north as central Alaska. They are common throughout the Eastern United States from Maine to Florida and even extend in isolated pockets down into Central America.
Like gray squirrels, Southerns prefer to make their homes in hardwood or mixed hardwood-coniferous forests. Middle-aged to mature forests are prime digs providing better nesting sites, sources of food and base-jumping platforms than younger stands.
Home ranges vary widely in size and overlap between individuals is common. Males tend to have slightly larger home ranges in areas where food is more plentiful while females favor smaller areas with ample nesting sites.
Not overly ambitious, flying squirrels are secondary cavity nesters meaning they use cavities in trees created by other animals or natural processes (woodpecker, fallen limb, hear rot, etc...). Squirrels line these cavities with a number of different materials based on the nest's intended use and the materials available in their particular area. Leaves, grasses, bark, twigs, moss, lichens, fur, feathers, twigs and man-made materials can all be on the list when a squirrel sets out to deck out their den.
There are three basic nest/den types. A refugia is a small den that is used only overnight during a foraging trip or as young squirrels leave their natal den to find their own home range (kind of like a buddy's couch). A natal nest is a larger one in which squirrels are born and raised. An aggregate nest is the largest den type and is shared by a number of individuals. Aggregate nests are unique to flying squirrels and almost always occur in a large tree cavity over winter.
While cavities are the norm, flying squirrels also employ a number of different types of shelter throughout their lives and to varying degrees throughout their range. During summer months, leaf and twig nests called dreys are built between tree branches. Despite having higher maintenance requirements than your typical cavity, these dens can be used for several years at a time.
There's an old adage that has fallen on deaf ears with our gliding friends. My editor would prefer I paraphrase: don't x where you y. Unlike many other types of squirrels, Southern flying squirrels, are not particularly hygienic when it comes to what goes down in the den. Especially in shorter term haunts, they have the habit of taking food to bed and not really bothering to get up to use the toilet. And like some dormitory spaces on Sunday, dense sometimes require a deep cleaning... or abandonment.
Flying squirrels do not actually fly. They are self-conscious so they self-aggrandize. They actually glide by extending their limbs, thereby stretching their patagium into a sort of wing. With their relatively long limbs, the patagium creates enough surface area for the squirrels to glide for considerable distances. While flights from tree to tree average sixty feet or so, some Northern flying squirrels have been recorded traveling over ninety meters on a rare glide.
Flight mechanics: Before hurling themselves into the night sky on a pseudo-wing and a high-pitched prayer, Southern flying squirrels tend to peek out over their launch pad and size up their target and surroundings. After this quick bit of what is likely triangulation, it's Red Bull time. Once airborne, flying squirrels are fairly nimble little gliders. Muscles and specialized cartilage on the fore-limbs allow the squirrel to adjust the are of the leading edge and the overall area of the "wing." They can make turns as sharp as ninety degrees to avoid obstacles.
While minor adjustments in the wrists and ankles govern trajectory, it is the tail that allows for gutsy landings. By lifting their large, flat tail, the squirrel alters its trajectory, quickly pivoting upwards and using its patagium like a parachute to decelerate and reduce the shock of landing. Once they've touched down, the squirrel always scampers to the far side of the target tree to avoid potential pursuers. That neat trick aside, the squirrel's wing-loading is about one pound per square foot, 2-3 times that of most bats. Higher wing loading does not allow the squirrels the acceleration, turning or climbing ability of their fellow acrobats of the night — even at the same speed and trajectory. The comparison is actually a bit of hang-glider versus jet fighter as bats can create lift and thrust... call it a point of interest for the pilots and physicists out there.
When the dinner bell rings, there's not a lot of nose-wrinkling: the diet of the Southern flying squirrel is broad and varied. Nuts and seeds of all types of course as well as flowers, buds, fruits, berries, fungi, lichens, sap, soft bark, insects, spiders, eggs, nestlings and even carrion.
They typically forage as much as possible amongst the trees but are not unwillingly to make trips to ground for specialty items. They are somewhat clumsy off the wing though and always stay within "safe scamper distance" of a protective tree. Like some of their cousins, flying squirrels are scatter-hoarders; when winter looms, they collect vast amounts of nonperishable food items and store them in a number of shallow holes or larger "larder cavities" in trees.
Flying squirrels are active throughout the year though they may take a week or so off during spells of severe winter weather. At this point, groups of squirrels will often find a large cavity to form an aggregate nest. In groups of 10 to as many as 50, the squirrels are able to conserve collective body heat by huddling together through extended rough patches.
Perhaps the most social of all squirrels in and out of the nest, Southern flying squirrels have been seen flying and foraging in groups and have a clear system of communicating with one another. They vocalize with bird-like, chirping noises — often combining these with tail bounces and other physical cues to indicate danger.
Like gray squirrels, flying squirrels mate twice per year with the exact timing depending on geographic distribution. In Ohio, mating takes place between April and May and again between August and September. The young are born hairless, blind and generally without purpose beyond nursing. By the end of their first week, ears have opened and fur has begun to grow; by the end of the first month their eyes have opened and they will begin to take notice of solid foods. After two months, the pups have been weaned and are capable of almost-independent living... the teen days. Short lived. By four months, almost all pups will be fully independent and capable of taking to the skies in short, controlled bursts of gliding action.
Well... people generally top this list but there are some other critters out there that aren't impressed by the flying squirrels antics either. Or maybe the antics are just less impressive than the flavor; cute often equals delicious after all! Owls, snakes, coyote, weasels, martens, bobcats, lynx and domestic cats all have a taste for flying squirrel meat... but the squirrels are no pushovers.
Aware of how delectable they are, flying squirrels are always sensitive to their surroundings and on constant watch for predators. The most dangerous times for flying squirrels are the "teen" weeks when locomotion is still being honed and surroundings still being absorbed. IF they make it to adulthood, they have a number of ways of staying out of a stool sample.
The squirrel's coat is designed to blend into its surroundings. Much like the Predator (first movie except no dreadlocks or shoulder laser), they can be very hard to spot if they remain still. Since most of their predators use movement (at least in part) to hone in on prey, this is generally the squirrel's first line of defense.
Adult squirrels know their territories inside and out and are constantly aware of the closest available tree cavity.
When push comes to shove, squirrels can run, leap, glide and dart faster than most predators. Few pursuers can move from tree to tree as efficiently.
On the behavioral ecological level. So inbred is the fear of owls that, after a flight, flying squirrels always move to the far side of a tree after landing.