So to overcome gravity, the swan must sprint with all its strength, using the surface of the water as a runway. Its wings, like the wings of an aircraft, only generate sufficient lift when a fast stream of air is flowing past them. It takes tremendous effort for a swan to get into the air. Starlings sometimes flock by the thousand, forming dark clouds that twist and pulse as the birds swoop past each other in perfect co-ordination. Flocks also make finding food easier and give protection from predators. This is why ducks and geese fly in V-formations. If each bird flies slightly to the side of the bird in front, it gets a lift from currents blowing off the leading bird's wings. Small birds such as finches have ail up-and-down flight path because they shut their wings intermittently.įlying in a flock has several advantages. They conserve energy by riding on thermals or catching the wind. Long-winged birds like vultures and albatrosses are gliders. They are fast and have enormous stamina, but they use up energy quickly. As a result, their flight paths move up and down. Small birds tend to flap intermittently and close their wings for barely perceptible rests. To do so they must run across the water and beat their stubby wings as fast as they possibly can.īirds differ a great deal in their style of flight.
They find it much harder taking off from the sea after diving for fish, however. As they fall they pick up speed and their short wings begin to generate lift. Puffins get airborne by throwing themselves off cliffs. After reaching the top of a thermal, they can glide for miles without having to flap. To stay in a thermal they have to keep turning, which is why they are often seen circling. Once they get going, birds can conserve energy by catching the wind, gliding on air currents, or taking brief rests.īirds of prey and vultures soar to great heights by riding on upwellings of warm air called thermals. Wings work best when air is blowing over them, so until a bird has built up speed it relies on muscle power alone. For most birds, getting off the ground is the hardest part. But it takes tremendous effort to overcome the force of gravity and travel on nothing but air. Birds move through the air with such grace that flying looks effortless to our eyes.
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