Recently, I discovered that crickets, toads and bats aren’t the only nighttime visitors to my backyard. Letting my dog out one evening, I was startled by a small critter hanging onto my bird feeder. Caught in the glare of the porch light, the small mammal was motionless. Then in an instant it leaped, gliding silently off my deck to the woods below.
This nighttime raider was a southern flying squirrel (Glaucomys volans). Although they are found in deciduous forests of Eastern North America from Southern Ontario to the Gulf Coast, southern flying squirrels are not commonly seen because of their stealthlike, nocturnal habits.
Only 8-10 inches long, including the tail, southern flying squirrels are grayish to brown above and creamy white below, with a flattened tail, large ears and large black eyes.
Of course, the most notable feature is the thin, furry membrane of skin, known as a patagium, that runs along the sides of the body from the wrist of the front leg to the ankle of the hind leg. This membrane is what gives the squirrel its flying or, more accurately, its gliding ability. When the front and back legs are extended, the membrane forms a winglike gliding surface.
The membrane acts like a parachute and the flat tail serves as a rudder. This allows the squirrel to silently glide from tree to tree. Before landing, the squirrel drops its tail and lifts its front legs. This slackens the membrane and acts like a brake. Flying squirrels land as lightly and quietly as they glide and will immediately scurry to the other side of a tree trunk to avoid detection.
There are two breeding periods for the southern flying squirrel. The first is February through March and the second is May through July. Litters average between three and four young but can range up to seven. The tiny squirrels are born hairless with eyes and ears closed, weighing less than one quarter of an ounce. Development is slow. Ears open at three weeks; eyes at four.
The young are weaned by six to eight weeks and not active until that age. They are then capable of gliding. Females are devoted to their young, seldom leaving newborns, defending them and even moving them if the nest is disturbed.
Southern flying squirrels can produce two litters but only under favorable conditions.
Southern flying squirrels favor beech-maple, oak-hickory and live oak forests. Tree cavities serve as nest sites. Often a squirrel will use one cavity as their nesting site and others as feeding or refuge areas. Not surprisingly, their primary foods include nuts, such as acorns and hickory nuts, although they will also eat berries, seeds, fruits, buds, flowers, mushrooms and bark. Flying squirrels also occasionally eat animal matter such as insects, bird eggs, nestlings, small mammals and carrion.
As the days shorten, flying squirrels will begin hoarding food. Nuts are gathered and stored, either buried individually, stashed in nest cavities or in the cracks and crevices of trees.
Flying squirrels do not hibernate but may remain in nests for several days during severe weather. Groups of flying squirrels may also gather in one cavity to conserve warmth.
Predators include cats, owls, hawks, raccoons, weasels and foxes. But the amount and quality of habitat is probably the biggest threat these squirrels face. Southern flying squirrels require forests with mast-producing (nut-bearing) trees and cavities for nesting.
The Chesapeake Bay watershed was covered with forests when colonists first arrived. Since then, forests have been fragmented, cleared piece by piece, to make room for roads, businesses, farms and homes.
Between 1985 and 1995, 471,000 acres of forests, about half the size of Delaware, have been lost. The Chesapeake Bay watershed continues to lose about 100 acres of woodlands a day. In many places, only small disconnected patches remain.
The loss of forests affects the southern flying squirrel as well as other wildlife that depend on woodlands for habitat. Game mammals, migratory birds, fish, reptiles and amphibians need forests and forested streams for food, water, shelter and breeding sites.
The loss of forests also affects water quality of local waterways and ultimately the Chesapeake Bay.
Forests capture rainfall, reduce runoff, filter nutrients and sediment and stabilize the soil. They are also one of the least-polluting land covers. Although forests cover 60 percent of the Chesapeake Bay watershed, they contribute less than 14 percent of total nitrogen and 3 percent of total phosphorus.
Forests affect the quality of our own lives. They offer us a place of natural beauty and recreation. Smaller tracts of woodlands usually result in limited access for hunting, fishing, hiking, camping and other outdoor recreation.
The conservation of our remaining forests, as well as forest restoration, benefits not only small woodland creatures like the flying squirrel but the entire Chesapeake Bay watershed and all of us who live here.