Simon Barnes assesses the flying capabilities of Sierra Gorda‘s flying squirrel in his latest post in his blog series, Barnes’s Bestiary.
The thing about Southern Flying Squirrels is that they’re no good at flying. Well, they can’t fly at all, in the sense of powered flight, so they’re really southern gliding squirrels. And the truth is they’re not all that crash-hot at gliding.
They live in Canada and the United States down into Mexico, including the Sierra Gorda, where World Land Trust supports a project safeguarding an area of cloud forest. Southern Flying Squirrels are one of around 50 species of flying squirrels that live mostly in the Americas and Asia.
And none of them is what you might call a great flier. Their world is night-time forest, and at dusk you can see them setting out on the night’s work, making precarious glides from tree to tree: as comic a sight as you will ever see.
Each flight looks utterly reckless. Against every piece of good advice you send them from the ground, they launch themselves across the clearing, wobbling violently, eventually making what looks like an extremely lucky landing on a tree. Then, just as you’ve breathed a sigh of relief, they’re crazy enough to try the whole thing all over again.
Glide ratio is the amount of ground travelled for the amount of height lost: a wandering albatross glides in still air at 1:22, or 22 yards further on for every yard dropped. A BASE-jumping human in a wing-suit can get as much as 1:3; a flying squirrel is below 1:2.
So this is not evolutionary perfection. The gliding membrane – the patagium – of a flying squirrel is a kind of Heath Robinson device, cobbled together from the parts available, and if it’s not exactly good, it’s good enough. Good enough to allow them to make a living.
And that’s evolution for you. It’s not about perfection, it’s about survival. Southern Flying Squirrels ply their trade in the darkness of the forest night with the help of their jury-rigged wings – and it works.
Let’s not be snobbish. We humans are also makeshift constructions put together from spare parts. Our upright gait frees our hands to do clever stuff: we pay the price in back pain, the most frequent complaint recorded in the NHS. Like the southern flying squirrel, we’re not that good, but we’re good enough.
MORE INFORMATION
Southern Flying Squirrels can be found in the ancient cloud forests of Sierra Gorda in Mexico, which is supported by World Land Trust’s Buy an Acre programme.
A donation to Buy an Acre can save 1,000m² of this habitat for £25, and one whole acre can be saved for £100, which will be placed under the protection of our in-country partner, Grupo Ecológico Sierra Gorda.