During our planet’s history, powered animal flight has emerged in four animal groups – birds, bats, insects and extinct flying reptiles called pterosaurs. How and why these four developed wings and took to the air are matters of heated debate among scientists.
Hummingbirds are among the smallest of flapping birds. And they’re the fastest flappers, beating their wings up to 80 times a second. They are the only birds that can fly backwards.
The grey-headed flying fox has wings of fine skin supported by arm bones and elongated fingers.
Flexible finger bones allow bats to radically alter wing shape and aerodynamic characteristics.
Insects were airborne more than 340 million years ago. How they developed wings is a mystery. Biologists think they sprouted outgrowths or appendages on the throat that helped them to parachute or glide when falling from heights, but originally had other uses. Gradually these outgrowths became the more manoeuvrable wings.
No bird or bat can match the aerobatic virtuosity of a dragonfly, such as this damselfly.
Flapping two pairs of wings – sometimes synchronously, sometimes out of phase with one another – a dragonfly can reach 60km/h, fly backwards, glide, hover and pivot on the spot in mid-air.
A kingfisher dives for its dinner. Birds evolved some 150 million years ago from bipedal theropod dinosaurs that already had wishbones and feathers – for insulation or display. How the dinosaurs became flappers is disputed.
A flock of starlings. The amazing way the flock coordinates movements during flight is another marvel of the natural world. Starlings – sometimes in their thousands – move in a way called murmuration, where they constantly, but synchronously, change direction within the formation.
A Major Mitchell’s cockatoo (Cacatua leadbeateri) in flight.
Most wings, but not all, have a slightly curved upper surface and a less curved or flat lower surface. They are mostly rounded at the front (the leading edge) and taper to a sharp rear (the trailing edge).
A green lacewing (Chrysopa oculata).
These four-winged insects add another layer of complexity to flight – their fore and hind wings interact.
Peregrine falcons are the fastest birds, reaching up to 300km/h in a dive. The fastest in flapping flight is probably the white-throated needle-tailed swift, clocked at 170km/h.
The humble locust can fly hundreds of kilometres without refuelling – 500km is not an unusual jaunt. Locusts have even been known to cross the Atlantic Ocean, admittedly with the help of a storm or two.
An eagle owl in flight. An example of the upstroke of flapping motion. The wing is flexed and feathers spread to allow air to pass through.
Evening bat (Nycticeius humeralis) in a dive. Bat wings are rich in blood vessels. A system of one-way valves in the vessels prevents the blood from pooling at the ends of the wings, during flight.
A ladybird with wings outstretched. Insects don’t have lungs; instead, oxygen reaches the flight muscles and other tissues via a network of internal tubes called spiracles. These are open to the outside air through the surface of the exoskeleton.
The wandering albatross has the biggest wingspan of all birds, measuring up to 3.6m. Albatross wings are long and narrow for gliding and soaring in strong winds.
A Harris hawk coming in to land. Two pairs of flight muscles power the wings. The largest – the pectoralis muscles – pull the wings down. The smaller supracoracoideus muscles raise the wing, acting through an ingenious pulley system.
Larger bees seem to defy the understanding of flight, being quite heavy, with very light, small wings – but they seem to fly with ease.
Flipping over between strokes, insect wings generate lift on both the upstroke and downstroke.
Greenfinches. On a downstroke, wings sweep strongly forward and downward. The wing’s twist ensures that the leading edge is tilted progressively downward in the outer portion of the wing. Thus, close to the body, the wing generates lift that supports the animal’s weight and near the tip the lift provides thrust.
A greylag goose has its feet down, to slow itself down to prepare for landing.
Tow essential features for super-efficient flight are lightness and strength (compared to size). To this end, avian body components have been pared down to the minimum.
Lesser long-nosed bat (Leptonycteris curasoae). The highly elastic material of a bat wing, as well as tiny muscles in the membrane allow a bat to radically alter the shape of its wing during flight. Because a bat can vary the wing’s ‘camber’ (its curved aerodynamic profile), it can modify the wing’s performance in a more subtle way than a bird can. In this way, the bat is highly manoeuvrable.
Home Topics Wildlife Gallery: The mechanics of flight
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