Nature Notes: Flying Squirrel
The afternoon slipped away quietly as another Indian summer day drifted into memory. At the end of each day, soon after sunset, there comes a time when the light suddenly drops as if a switch flips from daylight to dusk. Leaning against an ancient black cherry tree, I enjoyed the solitude of the forest while anticipating the walk back to the cabin in near darkness listening for creatures of the night to begin their conversations. The still of the moment was disrupted by a soft “whish” from behind, and something landed gently on the tree just in front of me. Then I heard a soft chirp.
Expecting to see a small bird of some sort, I slowly raised my head to see my new neighbor. While the creature had flown to its perch, it looked like a mouse or small, gray chipmunk clinging to the tree bark. It soon dawned on me that it was a flying squirrel, my first sighting of one. The squirrel regarded me for a few seconds with an apparent mix of surprise and curiosity, then with a clucking noise it scrambled up the backside of the tree. I did not see the animal again so I assume she remained hidden well above me or she launched to a distant tree for safety.
There are two primary species of flying squirrels in Maine, the northern (Glaucomys sabrinus) and the southern (G. volans). The northern is the historic resident here and north across Canada, but habitat loss and a warming climate have allowed the smaller, but more aggressive southern flying squirrel to expand its territory. Both squirrels are colored in tans and browns, making identification difficult, but the northern has a grayish belly while the southern has a white belly. The northern is larger by a couple inches, reaching 10-12 inches at maturity with a weight of just a few ounces. Both species are almost entirely nocturnal, as indicated by their long whiskers and oversized eyes, which show that they are adapted for movement in low light conditions.
These lovely, shy creatures do not actually fly, of course, but rather they glide. Large flaps of skin called patagia stretch among all four legs and when the squirrels launch themselves from on high, the skin serves like a parachute allowing them to catch enough air to soar up to 300 feet horizontally. The flattened tail serves as a rudder, allowing the squirrels to carve semicircles in the air. Just before landing, the squirrel flares upward in a movement that sheds speed and allows the squirrel to land on four legs to absorb the shock. If you live on the ragged edge you can purchase a special flight suit that mimics the patagium, allowing base jumpers to soar from amazing heights down through canyons to the ground below (I’ll film the action while you try it!).
Flying squirrels are omnivorous, eating a wide range of foods including nuts, fruit, seeds, buds, tree sap, insects, flowers, carrion, eggs and baby birds. The northern flying squirrel particularly favors fungi and certain lichens, resulting in their preference for moist, mature conifer stands where the predominant tree species are hemlock, spruce and fir. Mixed stands with mast-bearing trees like maple and beech are also attractive. Rotting wood on the forest floor is a fertile spot for favored foods. Although they are awkward on their feet, the squirrels are known to scavenge for buried fungi like truffles. Scientists have confirmed that the spores of some lichens and fungi pass through the digestive tract of the squirrels, thereby aiding the spread of desirable foods. Priscilla Seimer has told me with great delight of watching flying squirrels coming to her bird feeders at last light. If she is quiet the squirrels will tolerate her presence on the deck as she watches them feeding.
In researching this article I found many inconsistencies among the various sources regarding aspects of the flying squirrels lives, including breeding and rearing of the young. The challenge of course is in observing a reclusive animal that is active at night and wary of any larger creature. Flying squirrels are known to use several nests during the year and prefer cavities in old growth trees. Most sources agree that breeding takes place between March and May with the male or “buck” pursuing multiple females. The female or “doe” is on her own after her pups are born, following a gestation period of five to six weeks. The litter varies from one to six and the pups are born helpless. Their eyes open at one month old and the pups can leave the nest at six weeks of age. They are weaned after two months and “flying” at three months but may continue to live with their mother for another month or two before moving out. In warmer climates the southern flying squirrel has been documented to have two litters each year.
While flying squirrels are known to store some food for winter, they are not as active in this regard as chipmunks, red and gray squirrels. While they prefer to stay aloft in abandoned nests, den trees or in your attic, flying squirrels will use separate holes underground for dens, defecation and food storage. Another favored shelter is a bird nesting box placed by humans. Julia McLeod related a series of trips in winter to clean out wood duck boxes that resulted in the surprising discovery that flying squirrels were occupying the boxes, much to the delight of her dog. I have discovered as many as four squirrels in screech owl boxes, sharing body heat as cold temperatures arrive. Given their small size, flying squirrels do not hibernate or go into a state of torpor in winter but remain active to stay alive. The practice of sharing winter dens makes sense, and the squirrels can keep an eye out for each other and predators while foraging aloft or under the snow. A cluster of flying squirrels is known as a colony, or my favorite, a scurry!
As always, there are localized colloquial names for flying squirrels. Some folks call them “night squirrels” while the First Nation people use the term “assapanick.” The French Canadians have a wonderful name for them, “les grand polatouche.”
While you may not have seen one of these diminutive creatures, they are reasonably common and are not listed among the threatened species in our state. Other than predation by owls, hawks, marten, lynx, bobcats, weasels or fox, the biggest threat to flying squirrels is probably habitat loss. In actively managed forests there are fewer standing snags with nest cavities and pests like the wooly adelgid are knocking back the population of hemlocks in our state. Some fans of the squirrels actively install nest boxes designed for their use (you can find plans on the internet).
Those of us of a certain age remember well the fictional Rocky J. Squirrel who starred in cartoons between 1959 and 1964 with his faithful sidekick Bullwinkle J. Moose. If that is your only reference point on the unique flying squirrel, then perhaps you need to spend more time sitting quietly in the forest as day becomes night (with appropriate insect repellents liberally applied).
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