Which Vermont mammal is so secretive that a woodsman may go a lifetime without seeing one? The lovely little flying squirrel. Our most nocturnal mammal, almost entirely arboreal, it sleeps in languor throughout the day in a tree-hole nest (or your attic), sometimes together with others of its kind, especially in winter when it gathers with others for body warmth.
Flying squirrels emerge in late evening, becoming extraordinarily active all night long, romping and scrambling through the forest, gliding, chasing one another, chittering and churring audibly. I rarely see them but know they’re around by signs of activity in their preferred stands of pine, maple, and birch and from the results of midnight visits to our bird feeders near the woodline. I’ve heard them during nighttime forays into the surrounding forest, but they are ventriloquists and impossible to locate. Most people never know a population of these small rodents lives nearby.
Two species of flying squirrels live hereabout, and both have inhabited North America since the last ice age. In Vermont and New Hampshire, apparently only the uppermost reaches on the Connecticut river valley are without the smaller Southern flying squirrel. The slightly larger, heavier Northern flying squirrel’s range extends across Canada, all through New England, and down the Appalachians as far as Virginia.
Sitting and manipulating a nut in typical squirrel fashion, a flying squirrel looks as though its skin is much too large for its chunky little body, an effect caused by a large flightskin that stretches from special cartilage on the wrists down to the ankles. This flightskin-parachute allows a flying squirrel to glide up to 150 feet from treetops, and not always on a downward slope. By angling its legs to adjust the flightskin, and by steering with its flat, bushy tail, a flying squirrel can ascend at the end of an accelerating glide almost to the height from which it started.
Those who have studied flying squirrel behavior say that when one is about to fly, it first raises its forepaws to estimate the distance to the exact point of landing. Then it leaps, spreading arms wide as the wrist cartilage splays out to stretch the flightskin tight against its hind legs.
At a glide’s end, a flying squirrel changes its near-horizontal path by pulling up on the flightskin and using its tail as a rudder until the body is almost vertical. The flightskin then serves as an air-brake, and the raised, outstretched limbs cushion the gentle, silent impact upon a tree trunk.
Immediately after landing, a flying squirrel will dash around to the other side of a tree to avoid the possibility of a pursuing owl. But this ruse doesn’t always succeed; sometimes these dashes end right into the jaws of a hungry fisher or a rare marten. Both of these mustelids prey upon the little squirrels, although owls are their greatest foe.
On the ground, a flying squirrel’s cumbersome flightskin makes it awkward and slow compared with other squirrels, and thus more easily caught. But airborne in the woods, they are forest speedsters: soaring between trees; feinting and tussling with one another; competing in aerial acrobatics.
If you have a chance to examine a flying squirrel, you’ll be charmed by its elegance, its thick, glossy coat, its tiny, rounded head. You know it is a nocturnal creature by the large, dark, protruding eyes. Vision and acute hearing are essential to successful aerial
navigation through a dense forest.
Unlike its chipmunk cousin, which is about the same size, a flying squirrel has no cheek pouches but carries food in its mouth back to caches in the trees. It eats buds and nuts, berries and fruit, and any insects it’s able to catch. Flying squirrel populations are probably stable, although we know little about their overall numbers. They produce two litters a year (up to six young at a time) after a gestation period of 30 days: one litter in late winter or early spring, the other in midsummer. The tiny young are hairless at first, not weighing even an ounce after a month. If danger threatens, the mother gathers her young into a compact bunch, picks them up in her mouth, and scurries and glides away to safety.
A fastidious little animal, it is a good housekeeper, with roomy nests lined with soft moss. Old woodpecker holes are favorite retreats. A logger I know remembers how sorry he was to have cut one tree, not knowing a hole was occupied. He picked up two confused little animals, shocked out of their daytime torpidity, and took them to another tree where they scrambled aloft and sailed away into the forest.