Man vs Birds: The art of aerodynamics

Some birds do of course need runways, whether on land or water. The great Indian Bustard does a running take-off. Vultures too need to trot as fast as they can, flapping their gigantic wings before becoming airborne. (Alas, if they’ve overeaten this may not happen!) Albatrosses have special runways facing the wind that end at cliff edges. On the water, coots and geese splash frantically across the surface, beating their wings before achieving lift. Some ducks like pintails and teals do a vertical take-off, especially when they’re panicked. Pelicans landing on water stick out their webbed feet to brake as they splash down (‘reverse thrust!’), and always convey the impression that they’ve come down too fast!

But think: nearly all our aircraft (save jump jets) need lengthy runways to land or take-off. A big bird like a stork can touch down on a spindly branch or chimney top without fuss. Also, unlike most aircraft, birds fold their wings into their bodies when parked, taking far less space.

There’s more: aircraft need powerful engines, jet or propeller driven, to deliver the thrust required to enable their wings to generate enough lift. In birds, the wings do both. Powerful muscles enable the wing to flap rapidly, providing the thrust. The design of the wing itself is made for lift. And even these muscles can be specialised. Long distance endurance fliers like migratory geese have blood rich red muscles that are constantly fed a supply of oxygen to burn, which is why their meat is red. Birds like partridges and pheasants have glycogen-powered ‘white’ muscles to provide them with a sudden burst of energy to enable them to blast away from predators; hence, their white meat. But these are anaerobic, so the bird tires rapidly.

The flight pinions actually act like propellers, twisting and turning as the bird flies. Usually the down-stroke is the power generator, the upstroke a reloading, though some birds can twist their wings along their axes to generate lift and thrust both times. Also the pinions are cambered – slightly curving over their tops – in order to provide lift. Hold a kite flight feather (you can often find them on the ground when the birds are moulting) lightly between forefinger and thumb and draw your hand swiftly forward, and you will actually feel the feather attempting to move upwards.

While landing, aircraft use their flaps to slow down and lose height; birds have a special tuft of feathers on the leading edges of their wings called the alula, or bastard wing, which pops up just before they touch down. You can observe this most easily in pigeons. While gliding or soaring, the wingtips of birds like vultures and kites flex upwards to assist aerodynamic efficiency, something many of our aircraft now have too.

We get breathless while climbing heights due to the paucity of oxygen, yet birds like bar-headed geese fly at around 30,000 feet over the Himalayas while on migration, thanks to their extraordinary respiratory system that enables a continuous supply of oxygen to their blood while flying.

Migratory birds fly in their famous ‘V’ formation because eddies of air coming off their wing-tips assist lift in those flying just behind them. While the leader does the hardest work, it changes places when it’s done with its stipulated duty hours!

Our fighter jets bomb and strafe and hunt down other warplanes in ‘dogfights’. Birds too use flight for combat, piracy and to hunt. Their wings are designed to suit their habitats: hunters like sparrow-hawks have broad, short wings that enable them to twist and turn through tangled woodlands. Seafaring albatrosses have the long tapering wings of gliders, enabling them to catch the wind coming just off the waves, while vultures and condors have big broad wings that enable them to catch the thermals rising from the hot earth and soar for miles without so much as a wing-beat.

We show off our air prowess at air-shows with acrobatic displays, birds show off similarly: watch a paradise flycatcher displaying with its silken tassels, or eagles in a somersaulting tangle with one another as they court, separating inches above the ground! Also, flocks numbering thousands can fly in breath-taking synchrony (the famous murmurations of starlings) without colliding and without even a squadron-leader! Birds never suffer bird-hits!

And as for service and maintenance, birds are way ahead of us. They will assiduously preen and clean their feathers daily; tattered feathers are dropped and replaced symmetrically (so that flight balance is not upset). I once watched a darter conduct a complete overhaul of its plumage and walk away after 45 minutes; it was still going strong.

I will always be gobsmacked as I watch a giant Airbus A380 lift-off. But there’s nothing to beat a squadron of flamingos racing over a shallow lake, necks craned, taking to the air.