Structure and Flight

Do they not see the birds committed to fly in the atmosphere of the sky? None holds them up in the air except God. This should be (sufficient) proof for people who believe. (16:79)

That birds can fly and so efficiently is miraculous. In order to work, such a flying machine must be amazingly lightweight and yet incredibly tough and strong. To take off and maintain flight, the bird can’t be too heavy. Yet to survive the conditions faced in the air and the force of landing, it must be tough so as not to break on impact. These two qualities (lightness and toughness) are exactly how a bird is constructed.

The skeletal framework of a bird is rigidly interconnected with a very sturdy spinal column of fused vertebrae. The neck is strong but incredibly flexible as it must have the strength to support the head (keeping it motionless when in flight) yet flexible and ready to swing it suddenly in any direction, bending far downward or upward to spot prey or predators. The number of vertebrae in a bird’s neck varies from long-necked to short-necked birds. This may sound obvious. But a mouse has the same number of cervical vertebrae as a giraffe (seven). Birds have a minimum of 11. Flexibility of the neck is achieved by a system of long bands of muscles and smaller muscles that are perfectly coordinated. From the slow turning of an owl’s head to the flash of a heron catching a fish, it’s a masterful machine.

Bones in the bird are hollow and thin-walled for lightness with internal struts for support. All weight is concentrated toward the center of the bird. At that center is a very large breastbone to which are attached the pectoral muscles, the mighty muscles which drive the wings. Flight muscles may account for 25-30 percent of a bird’s weight, compared to pectoral muscles in the human which weigh less than one percent of total weight. These muscles working to drive the wings build up great heat. To counteract this, the bird has the most efficient respiratory system of any vertebrate. Rather than a single pair of lungs the bird has a system of air sacs throughout the body even in some of the hollow spaces in the bones. The air is taken in quickly to all important parts of the body and the bird’s faster heartbeat provides rapid circulation.

Good eyesight is an important prerequisite of flight. A bird relies more heavily on vision than most animals. In some birds their eyes actually weigh more than their brains. Birds can see distant things as much as eight times more clearly than man can, and they also see close up much better. Most birds have both monocular and binocular vision. They can rely on what one eye sees close up and then count on sharper binocular vision for distances.

Most important to flight are the wings and feathers. The wing is really an arm with a large ball joint fitting into the socket in the shoulder. This is a specialized joint allowing great mobility. The way the bird can rotate as well as flap up and down gives the bird the ability to maneuver, slow down, change direction suddenly and land gracefully.

The feather is a unique and wonderful creation. It’s light yet sturdy, flexible, versatile and easy to care for, provides cushioning, thermal insulation, and is water repellent and replaceable. Bright colored feathers are important in some bird species for attracting a mate and for territorial displays. Some birds have feathers camouflaged like their surroundings to help them hide.

The simple looking feather is actually a very complex mechanism. There is a center shaft attached to the skin. From this project many parallel branches or barbs which in turn bear smaller barbules, which are equipped with hooks and barbs. All of these barbs catch in one another like little zippers forming a smooth surface. If the feather is ruffled and the connection broken, it’s easily smoothed out and rehooked. On each feather there are millions of these barbules hooking the feather together. When the wings are folded the feathers lie over one another like roof shingles with air spaces between to insulate against heat loss.

With all the bird does, there is continuous wear and tear on the feathers, so they must be replaceable. That’s why birds molt on a regular basis. Molting is a precise process, triggered in the least severe season. The feathers are discarded usually in pairs (one from the right side and the corresponding one from the left). And never so many that the bird can’t fly, although it may be weakened. To compensate the new feathers grow in very fast.

None holds the birds in the air except God

God holds them in the air. God gives them the physical construction to fly, the use of wings. They can raise and lower the wings, can move them forward or back, they can reduce the wing area, can rotate the wing at the shoulder, can twist the wings. Then God gives them the instincts to know how to do it. Birds don’t study the laws of gravity but they use them. From great heights, they’ll tuck their wings and fall straight down, then pull out the wings to provide resistance to slow down and land. They make it look easy.

Hummingbirds can fly backwards. Penguins, who don’t fly, use their wings like a powerful oar to move quickly through the water. Hawks can turn upside down in full flight to catch smaller birds trying to escape, then right themselves and fly on without missing a beat.

Birds use the wind with great skill, as if they studied science. Some birds use land drafts to soar and glide, like an eagle using the currents in a canyon. Over water, seabirds are incredibly adept at using drafts. Gulls also have the instinct to use obstacles, like ships, which create extra updrafts. They’ll follow motionless, looking as if they’re tied like a kite on a string.

The structure of the bird and the miracle of flight are signs from God if we choose to see them. This is a proof for people who believe.

The Mystery Of Migration

Certainly of all things about birds, one of the most incredible is migration. In ancient times, all kinds of strange explanations were advanced to explain why certain birds disappeared in certain seasons. It was believed swallows spent the winter sleeping at the bottom of lakes. Aristotle announced that the European robin changed into another bird, the European redstart, at the approach of summer, and then presumably back into a robin. The Romans generally agreed, but claimed swallows turned into frogs. In 1703 an Englishman wrote that birds flew to the moon taking 60 days to get there and then on arrival finding no nourishment went into hibernation.

We now know that when birds disappear from one location it is because they migrate. We know when they go, which birds go where, over what route. Some are truly incredible journeys. The sandpiper goes from Canada to Tierro del Fuego. The golden plover travels from the arctic to the pampas of Argentina. Some barn swallows go 9000 miles from Alaska to Patagonia. Scandinavian swallows end up at the southern tip of Africa. Little warblers weighing less than an ounce take solitary night journeys from Germany to central Africa. The arctic tern is the champion long distance flyer, going between 10 and 14 thousand miles in its migration, breeding at the North Pole and wintering in Antarctica.

Those are the things we know. What still baffles scientists is the how. What prompts them to start when they start and to return when they return? And how do they find their way? For each new theory advanced, tests were performed which disproved it. Do they use landmarks? A species of stork when migrating south through the North American plains makes an abrupt turn to the west at approximately Great Falls, Montana to cross the Rockies. But it couldn’t be landmarks, because birds cross vast stretches of ocean to remote islands. The golden plover travels over 2000 miles from Alaska to Hawaii over open seas. Some curlews go 6000 miles from Alaska to Tahiti with no landmarks to follow.

Birds use the position of the sun. Experiments with birds in cages showed that they would orient themselves to the sun and become confused by mirrors changing the sun’s position. Yet many species of birds migrate by night. They then must use the stars. But while it’s true that birds rarely start out on a cloudy night, they will continue their migration even if clouds obscure the stars.

It is generally acknowledged now that all these factors apply. Birds do use the sun by day and the stars at night and also the earth’s magnetic field, perhaps also wind currents, landmarks and deep ocean sound vibrations. How they use these things remains a puzzle.

And how do they know where to go? In an experiment a bird was carried from its burrow in Wales to Boston, Mass. and released. Within two weeks, it was back in its burrow, 3000 miles across the Atlantic, totally unfamiliar territory. The bronze cuckoo of New Zealand is raised by foster parents who do not migrate, yet the young cuckoo migrates over 2500 miles of open ocean to the Solomon Islands for its first winter.

They must carry within them a "map," which shows them instinctively the route and the destination. And they must also have within them an internal clock that tells them when to leave. The swallows return to Capistrano on the same day each year and the vultures to Hinkley, Ohio (so man can marvel and turn it into an event.)

Migration is an amazing phenomenon. It’s a difficult journey and many perish, providing food supplies for other animals along the migration route. A Mediterranean falcon lays its eggs later in the season than any other bird so it can feed its young off the migration of other birds.

To help conserve energy and insure that the most individuals complete the trip many birds fly in formation. The beautiful V-shape of the Canada goose and others is the most efficient use of drafting. It saves a lot of energy for the whole flock, each bird able to rest on the air currents created. Who teaches them that?

While the ornithologists and scientists struggle and experiment and test out theories, we know the truth. A bird flies because God is the One who holds it in the air. It migrates along mysterious routes because it follows God’s plan. Its flight is part of its glorification of its Creator.

The robin doesn’t wish it were an eagle. The crow doesn’t care that he’s not colorful like the cardinal. The hummingbird doesn’t want to try fish for change like the duck.

That’s a lesson for us. A sign for people who understand and take heed. Our job is to worship God alone. If we can do that job even a fraction as well as birds do their jobs, we might just be fortunate enough to fly with them in heaven.