Many arboreal (tree-dwelling) animals have developed wing-like extensions called patagia, which are elastic membranes stretched between their limbs or toes. These flaps of skin are ideal for helping them glide through the air either to evade predators or to catch their own prey.
The southern flying squirrel is a nocturnal rodent capable of taking to the air and gliding from tree to tree in a single leap. The length of a single flight depends on the height at which the squirrel launches, but some can reach distances of up to 50 metres (165 feet). This form of gliding is known as volplaning.
The flying squirrel leaps out from a tree with its body tilted up and its arms and legs outstretched. After pushing off, the squirrel gains height and momentum. It then stretches its arms and legs out in front to help propel it forwards as it falls. Once the rodent gains altitude, it spreads its limbs to reveal a gliding membrane (the patagium) connected to the wrist and ankle on either side. These flaps fill with air, like a parachute, to create drag. The flying squirrel can dictate the direction in which it flies by steering with its legs, flattening its tail and stiffening the patagia, the two of which also act like an airfoil to generate lift. During the descent, the creature flexes its entire body and tail upwards. Doing this enables the squirrel to change its angle of attack at the last moment by slowing its speed through the air. Finally, as it comes in to land – typically on another tree trunk – the squirrel’s body moves into a vertical position by swinging its hind legs down and forward ready to grasp on to the new tree.
Flying squirrels are found in North America and northern Europe, living in nests or natural cavities high in the trees. When down on the ground, however, they’re a vulnerable target.
Flying squirrels are omnivorous and feast on a wide range of different food from nuts, fruit and fungi to many insects, bird eggs and even carrion from time to time.