Mark Eifer, age 10 of San Diego Cal
How do birds fly?
The flight of a bird is ,one of the wonders of nature. Mankind watched, vnndered, envied and studied the flying birds long before he built a machine that could take to the air, Each bird has its own style of flying. The partridge takes off with a whirr of wingso the owl swoops in silence. The swan uses his feet to launch himself from the water. The flicker flies on short, swift wing beats, the gull glides without effort and the eagle soars in lazy circles.
The principles of flight, however, are the same for ail birds: Flight is the mastery of the air. A bird uses the air much as a fish uses the water, He moves it this way and that piling it up in cushions to lift him aloft, piercing it to let himself through, To us, used to the solid grounds the air is a filmy nothing. To a bird, this filmy stuff can be used to hold his light body above the ground.
The birds body is built for flight, It is light and streamlined. The heaviest part is the chest. Here are the powerful muscles that work the beating wings. They are fixed onto a breast bone shappd life a ship's keel. This gives the whole body a streamlined, forward motion when cutting through the filmy air in flight.
Apart from those chest muscles, the rest of the birds body is as light as possible, The bones are light and slender and the large ones contain hollows filled with air. There are still larger air pockets in the body of the bird. They connect with the lung. The bird can take in extra oxygen and lighten himself at the same time.
Most important are the feathers each one a miracle of tiny filaments growing from a hollow quill. The feathers of a flying bird are wind proof and water proof. The filaments lock together with thousands of tiny barbs, The water‑proofing is done. with oily brilliantine which the bird applies to his feathers as he preens:
Nature has given the bird this body built for flight,, but he still has to learn how to fly. There is more to this than just flapping the wings. The bird must learn wind direction. For he uses this and the rising air currents to hoist himself and stay aloft.
Slow motion cameras show us the complex movement of each wing flap. The up‑beat is a quick flick with wing pinions outspread to let through the air, The down‑beat takes half as long again. The feathers are closed and wind proof as the bird pushes a pile of air into a cushion below him. The wings bend at the elbow joints to scoop up the cushions of air that hoist the bird forward and upstairs,
The soaring bird makes the best use of rising air currents to keep him aloft without effort, He uses his wings to climb upstairs and gain height, then he glides along slowly, slowly falling. Sometimes he drifts into a rising current that lifts his light body up again. Otherwise from time to time, he must flap his wings to make those airy cushions on which he climbs upstairs,