Southern Flying Squirrel

Glaucomys volans volans
Saturday, June 14, 2014

            Rarely glimpsed but often heard at the station, this small member of the Sciuridae family is a happy convert from its natural dwellings in hollow trees or woodpecker holes to the comfort of attics, birdhouses, and other human-made structures. These secretive, nocturnal creatures are found over the entire east coast of North America, from southeastern Canada to Mexico and Honduras.

            The most distinctive characteristic of the flying squirrel is its ability to “fly,” giving rise to both its common and Latin names (volans is related to the English ‘volatile,’ describing a substance that, like a flying squirrel, tends to enter the air). Loose flaps of skin connect the squirrels’ wrists to their ankles, creating a “gliding membrane” which they spread, sail-like, when leaping from high places. However, their leap is more than just a controlled glide—they can avoid obstacles and make 90-degree turns in flight. There are capable of covering 80 m in a single long glide; that is, starting from Lewis, they can glide half the length of the lawn! Just before landing, they raise their tail to change the direction of the flight upwards, and spread their limbs to serve as a parachute and slow their landing. Upon landing on a tree or other object, they will immediately move to the far side to avoid any pursuing predators.

            Apart from this ability, the squirrels are not conspicuous animals. They have a grey-brown body (although the color can vary across the range) and a white belly, separated by a dark stripe running laterally down their side. G. volans can reach 25.7 cm (10 in) in total length, some 9 cm smaller than the closely related northern flying squirrel (Glaucomys sabrinus). Another means of distinction can be found on their flattened tail, which is used for aerial control and can reach half their body length—G. volans lacks the darker tip typically found on its congener. Finally and most decisively, the belly fur of northern flying squirrels has darker roots, whereas that of the southern ones is white throughout.

            Flying squirrels are gregarious, and can be found in groups as large as fifty individuals in a single den during the winter. In very cold weather, they become torpid to preserve energy and body heat. During the mating season, however, females defend exclusive home territories, although male home ranges do overlap with each other. Females mate twice per year, in the spring and the late summer to early fall, depending on location. They typically bear 2-4 young, although litters can be as large as six. The females gestate for 40 days, which is not atypical for a rodent of their size—however, the young are not weaned for over two months after birth, which constitutes a very long time among similar organisms.

            The young are completely helpless at birth—their ears do not open for 2-6 days, and their eyes remain closed until they approach their first month. They are born naked, but begin to develop fur at around their first week. Although most flying squirrels do not survive their first year of life, their lifespan can approach 5-6 years in the wild.

            These squirrels are omnivores, eating everything from nuts, seeds, and berries to moths and junebugs to eggs, young birds, and mice. They are also known to consume large quantities of the subterranean fruiting bodies of certain fungi, playing a crucial role in their life cycle by dispersing the fungal spores in their feces. These fungi are among playing large roles in the subterranean, mycorrhizal relationships upon which many hardwood trees depend; therefore, the ecological importance of G. volans should not be underestimated.

            This male was captured in a live trap in the attic of Clayton.

Hazel Galloway