The smallest of the arboreal squirrels, the adult southern flying squirrel ranges from 5 to 6" in body length, with another 3 - 5" of tail, and weigh about 2 - 4 oz. This squirrel has a loose flap of fur covered skin, from the wrist to the ankle, that is used as a gliding membrane, much like a parachute. The soft, plush fur ranges from a mossy grey to a soft cinnamon brown, on the dorsal side, and soft white, occasionally with some rosy highlights, on the ventral side. The midline ventral white hair is white to the skin, which, along with size, helps distinguish it from its larger cousin, the Northern flying squirrel. (In the northern, the white hair is dark at the base throughout.) There are dark markings along both the dorsal patagium, and the eyes, sometimes along the edge of the tail. On the ventral patagium, the white hair is often dark at the base (near the skin). The hair covered tail is flattened, with the fur feathering from the base to the tip. The tail hair is coloured like the dorsal body, slightly lighter on the ventral side, but not white, like the ventral body hair.
The southern flying squirrel uses some vocalisation to communicate, including a commonly heard "tpsseet, tpsseet, tpsseeet" call that acts as an alarm, and softer chirping sounds, with occasional louder squabbling, that often sounds a bit like a parakeet. They also "chitter" their teeth, but this is not a sound one often is able to hear, in a natural setting. Sometimes, it's seen, more than heard. It is believed these squirrels also have sounds that are outside human range of hearing.
At the wrist, a piece of cartilage helps stretch the patagium when this little squirrel leaps into the air from an elevated position, with its limbs spread out from its body. This position provides the squirrel with the ability to glide to a lower position, with a lateral movement approximating 2- 3' for every foot of elevation (Thus, if the squirrel is 30' up a tree, a glide of 60 - 90' in length is possible - perhaps more, if the air currents are suitable. For the most part, glides are in the 50' range, but glides of up to 150' or more are possible. By shifting weight and adjusting reach, the flying squirrel is able to maneuver in flight - the tail placement may aid this ability, but the flyer is capable of the maneuvering even without a tail, or with just a partial tail. The body is generally held at about a 30 to 50 degree angle to the ground, until the squirrel is closing in on its landing target, most often a neighbouring tree. As the flyer nears the target, the lower body is thrust forward, and the upper body pulled back, making the hind and forefeet contact the landing surface simultaneously. Upon landing on a trunk, the squirrel most often runs immediately to the opposite side of the tree trunk. This behaviour may be an adaptation to avoid capture by following owls, the principal predator of this nocturnal squirrel. Flying squirrels also run very quickly up and down tree trunks, and tend to hop, when on the ground. Compared to their flight, their ground movements often seem awkward. But they are much like their distant cousins, the eastern grey squirrel, when on the ground - capable of darting quickly for a tree trunk, and usually circling the trunk, as they climb, to make it more difficult for following owls or other predators to give chase.
Biology & Behaviour:
A nocturnal creature, the flying squirrel is born pink skinned, naked, blind and helpless, following a 40 day gestation. Only the female is involved in raising pups. The characteristic patagium (gliding membrane) is evident at birth, as are delicate vibrissae (whiskers and other tactile hair). The pup can flinch, and with leg pushes, can squirm around in a nest, but most movement is not purposeful for the first few weeks of life. By the first week, the dorsal side is beginning to show a grey colouring. Between the third and fourth week, the large, dark, prominent eyes open, and the ears begin to "sit up" away from the scalp. By this time, the coat is beginning to offer real cover, and the belly hair is also coming in. Tail hair is still a bit short at this age, but is clearly on its way to a fine full feathering.
Soon after the eyes open, baby squirrels display a curiosity about their nest, and often the surrounding area. This curiosity often results in a fall from the nest cavity. Mother flying squirrels are very attentive, and yet, the unexpected fall can often result in the loss of the pup, to a prowling cat, before the mother squirrel can retrieve the wanderer. Many people have their first experience with these wonderful creatures by way of a cat bringing one home to the door step. Mother squirrels will attempt to retrieve missing pups, and can carry a pup of up to 5 weeks, when she must! (By six weeks, the pup is quite large, and momma can often make baby follow, rather than have to carry the baby!) To carry the pup, momma holds the pup in her forepaws, and turns it until she can get a grip with her mouth on its belly. The pup will then cling to its mother's head and body, allowing her limbs freedom for movement. With small pups, Momma can glide. With larger pups, short jumps are easier to manage, but glides are still a possibility.
When preparing for parturition, mother squirrels usually scout out an area, and have three or more possible nest sites already developed, should they be needed. By the time pups are 5 weeks, they are beginning to gnaw, although they continue to nurse. Most pups are weaned by 8 weeks, although they may stay in the maternal nest until momma departs to prepare for a new litter. It is not unusual for the mother squirrel to move her pups at about the 5 week age, and it is thought this may be precipitated by either external parasites making the whelping nest uncomfortable, or possibly due to urine making the nest unpleasant, or both.
A southern flying squirrel often has two litters per year, and it is not unusual for the second litter to remain with the mother through part of the winter. The breeding season runs from late December until perhaps May, but the female usually has but two fertile periods, and ovulation is generally over a 24 - 48 hr. time frame, during which she will be receptive to a male. The males also have a "breeding period", and a few months when they have a fallow (non-reproductive) period, with fairly abdominal testes (the scrotum appears flattened). Litters from one to 6 pups occur, but the most common number of pups in a litter is 3. When the pups are weaned, they will often nest together for a while, until their first spring, when they disperse in search of their own home range. Male ranges will overlap with other males, and with females, but females usually keep a home range free from other females, unless food and nesting possibilities are plentiful. This protection of a home range is likely due to the fact that the female needs to have several nest possibilities for each litter, in the case of the brood nest being invaded by a predator. Raccoons, snakes, martens, etc., all have a fondness for flying squirrels as prey, and have the ability to climb and invade a nest. Owls also prey on flying squirrels, but usually do not attack a nest. They will, however, often perch nearby, waiting for the opportunity to catch a flyer when it begins its nightly foraging.
Once weaned, flying squirrels begin for forage for food. Their gliding is instinctive - they do not need their mother to teach this behaviour. They do learn as they go, and make greater leaps and glides as they mature. They spend a great deal of time resting, and their awake hours are spent grooming, playing, foraging and hoarding nuts, acorns, seeds, etc. With few exceptions, they do not bury food on the ground, like grey squirrels, but rather cache nuts and acorns in tree cavities. Predominately, they depend on oaks, hickories, walnuts, beeches and pecans, for cache foods, and they eat as they find maple seeds, pine nuts, various catkins, sunflower seeds, pumpkin seeds, corn, berries, grapes, and large fruit, such as apples and pears. They also eat grubs, crickets, moths, and other insects, and have been known to take the occasional bird's egg, or even nestling, if they do not have to fight off the parent bird.
Flyers often live in small groups, of two to seven, usually family members (including momma), in the temperate months; and larger groups of mixed parentage in the cold months. They've been known to share a nest tree with several other species, such as their cousin greys, and even small owls. Some accounts indicate that in the winter, they will even share the same nest cavity with other species. It's believed this is likely for the shared warmth. They are active all year, but will remain nest bound, in especially harsh weather, and can slow their metabolism to accomodate the restriction in diet that remaining treebound requires. They are not often seen searching out water, more often relying on pools of rainwater found in tree crotches. In dry spells, however, they are often found drowned in horse troughs, and buckets of water. They are not good swimmers, for both their patagium and their fur interfere with swimming. In a vessel with no traction, like a water tub, they cannot get out before drowning. (For this reason, keeping a log branch or wood plank in all outdoor tubs may help to prevent these accidents.) Flyers are a bit more friendly with their own, than is seen in grey squirrels, and will often share a perch on a feeder, without hostility.
For Domestication and Lifespan Information, go to FlyerFactsPage2 ...
The music on this page is Claude Debussy's Clair De Lune
The illustrations are from John J. Audubon's Viviparous Quadrupeds of North America (1845 - 1848):
[upper] Oregon Flying Squirrel (plate xv) and [lower] Common Flying Squirrel (plate xxviii)