Come night fall, the forest is a whole other world. The atmosphere is rent with peculiar sounds, the forest floor is lit by strange neon lights and the crack of twigs underfoot echo into the night. This is the time when animals which were otherwise inactive during the day venture out, where they are free from most of their predators. Among these creatures of the night are the flying squirrels.
I remember gasping when I first heard about flying squirrels. Like Giant Squirrels, the flying ilk has a flair for acrobatics. Of course, they don't really fly- they glide. But it still boggled my mind. They were circus acts of a whole other kind.
Flying squirrels are said to have evolved from tree squirrels as an adaptation to habitats with tall and distantly spaced trees. By gliding, flying squirrels are able to rapidly cover large distances and thus spend more time foraging. Despite their nocturnal lifestyle, they still have predators like large owls and arboreal snakes, but by gliding they can escape predators more effectively. This peculiar form of locomotion is also more energy cost-effective than flying and running.
India has eleven species of flying squirrels found in deciduous, evergreen and semi-evergreen forests and are mainly distributed in the Himalayas and Northeast India except for the Travancore Flying Squirrel which is found solely in the Western Ghats and the Indian Giant Flying Squirrel which is distributed over most of peninsular India, having the largest range of all the species.
Indian Giant Flying Squirrels (Petaurista philippensis) vary in colour from grey to coffee-brown with a mottled back, a grey tail and pale undersides. They feed on fruits and leaves and have a fondness for fig fruits.
They nest mostly in tree cavities and are found in a mosaic of forests of tall trees and plantations. When dusk falls, they leave their nests and return only before dawn.
Glides of flying squirrels are a thrill to watch. Gliding has been the subject of much research, as some scientists believe it may be a precursor to powered flight. Two membranes, one between the wrist and the ankle and another from their wrist to neck are what help them achieve the feat of gliding. Large flying squirrels like the Indian Giant Flying Squirrel have an additional membrane between their tail and hind limbs.
To glide, the flying squirrel climbs high up a tree to the upper canopy and jumps down.
It then stretches its gliding membranes taut with the help of a cartilaginous wrist bone so that aided by the force of lift, it glides spread-eagle along an oblong trajectory.
While air borne, it uses its tail to manoeuvre and then billows its gliding membranes outwards to decelerate so that it can land lightly. A vertical trunk is usually picked for landing when glides are long.
Indian Giant Flying Squirrels have been known to cover distances as great as 90m in a single glide, although they prefer shorter glides. They also prefer climbing across tree branches when distances between trees are short.
While sitting on branches of the tree, they have a characteristic pose with their tail curved in an "S" behind their backs.
Indian Giant Flying Squirrels used to be extensively hunted for their meat in south and northeast India. Habitat loss is another threat, although populations in some parts of the Western Ghats were found to increase with disturbance to the forests.
There is a thin line between creatures of myths and fantasies, and the enchanting animals of our forests. These flying squirrels blurred the line for me.
Note : These photographs were taken in Dandeli by Gopi Krishnamurthy and are a rare glimpse of flying squirrels foraging and gliding during the day time; they seldom surface during the day as they are unable to escape diurnal birds of prey with ease. Instead, they remain in the safety of their nests until dusk falls. The images are an excellent natural history documentation of a nocturnal species.