Flying squirrels are fascinating mammals often misunderstood. While their name suggests bird-like flight, they actually glide gracefully through the air, covering impressive distances between trees. This unique anatomical adaptation allows them to navigate their arboreal environments.
The Art of Gliding
The most striking feature enabling a flying squirrel’s aerial movement is the patagium, a furry membrane stretching along each side of its body, from wrist to ankle. This specialized skin fold is supported by elongated cartilaginous extensions (styliform elements) from their wrist and ankle bones, providing rigidity. A flattened tail functions as a stabilizer, aiding in steering and maneuvering, and can also act as a rudder or brake.
To initiate a glide, a flying squirrel launches from a high perch, often bobbing its head to triangulate the landing distance. As it leaps, it extends its limbs laterally, stretching the patagium into a parachute-like “X” shape. During the glide, the squirrel adjusts its body, limb positions, and tail movements to control its trajectory.
Glides are not static; squirrels continuously change their velocities and forces. A typical glide involves an initial sharp drop to gain speed, a leveling-off phase, and an upward curve before landing. They can cover considerable distances, often 20 to 60 feet, with some recorded as long as 300 feet. Nearing their target, they raise their tails and drop their hind legs, creating a parachute effect with the patagium to reduce impact, landing vertically on a tree trunk.
Diverse Species and Their Homes
Over 50 distinct species of flying squirrels exist globally, categorized into New World and Old World groups. New World species (Glaucomys) are found across North America, from Alaska to Honduras. The two most recognized North American species are the southern flying squirrel (Glaucomys volans) and the northern flying squirrel (Glaucomys sabrinus).
Old World flying squirrels (Pteromyini) inhabit Asia and Europe. North American species are distinguished by size and fur: southern flying squirrels are smaller (8-10 inches) with entirely white belly fur, while northern species are larger (10-12 inches) with gray-based belly fur. These squirrels primarily reside in deciduous and coniferous forests, preferring areas with a dense tree canopy for arboreal movement.
Life in the Canopy
Flying squirrels are primarily nocturnal, a behavior that helps them avoid diurnal predators like hawks. Their large, dark eyes are adapted for excellent low-light vision. During daylight, they sleep curled in nests, often in tree cavities or abandoned woodpecker holes. They frequently change nesting sites, especially when not raising young or if a nest becomes soiled.
Their diet is omnivorous and varied, adapting to available food sources. They consume seeds, nuts, fruits, fungi, insects, bird eggs, and carrion. Southern flying squirrels are more carnivorous, supplementing their diet with eggs, young birds, and dead animals. They often store food, like nuts and seeds, in dens or hidden locations for later consumption, particularly during leaner winter months.
These social squirrels frequently den together, especially in winter. Communal nesting helps conserve body heat during colder periods, with groups sometimes consisting of up to 19 individuals. Their gliding ability aids predator avoidance, allowing them to quickly traverse distances and escape threats from animals like owls, snakes, and raccoons. After landing, they promptly scurry to the opposite side of the trunk to evade predators.