On December 17, 1903, at Kitty Hawk, North Carolina, the Wright brothers’ made history. Their famous flight lasted only 12 seconds and covered only 120 feet. The nose of their awkward craft bounced up and down along the way. But it was giant leap for humankind. Thousands of years of human dreams of flight had finally come to fruition.
If birds could talk, though, we would hear them mocking us: You call that flying? What a joke!
For all mankind’s creative brilliance, the construction of a mechanically powered aircraft pales in comparison to the ultimate flying machine – a bird. Everything about it is a masterfully engineered, tightly integrated series of components designed for flight. To see one glide in the wind is to observe poetry in motion.
From Egg to Air
It all starts in the egg.
Ranging in weight from less than an ounce to more than three pounds, a bird egg is a factory manufacturing a meticulously crafted mechanism ready for flight in a matter of weeks. Genes are switched on and off. Cells interact and communicate. They’re all part of an elaborate dance taking place on a stage with thousands of cast members doing everything they’re supposed to on cue, in the right order, in the right sequence, in the right time.
In almost no time, the organism goes from one cell, which could have become anything, to billions of different cells doing hundreds and hundreds of different kinds of tasks. At the end of the process, information has been translated into a physical product of stunning complexity, each part necessary for the bird to engage in the miraculous – taking flight.
The miracle starts with a bird’s incredible anatomy. Its wings are crafted in an aerodynamic way that produces lift as air moves rapidly over the curved top of the wing and slower beneath it. As a consequence, there is more pressure pushing up on the bottom of the wing than there is on top of the wing. In a sense, birds are actually sucked up into the air.
But the wings would not be very useful if not for the unique design of its bones. Whereas mammalian bones are solid, a bird’s bones are hollow, held together by extremely thin crossbeam-like structures attached to the top and bottom of the bone. These “beams” keep the bone strong, yet very light. If not for their specialized bones, birds could not fly; they would be too heavy.
An adult pelican, for instance, weighs more than 20 pounds and has the strength to fly hundreds of miles before landing, yet its entire skeleton weighs less than 30 ounces. The hollow bones reinforced by an internal network of girders and struts allow it not only to free its body from the bonds of gravity but are durable enough to withstand the constant stress of flapping takeoffs and landings.
However, a bird’s wings and skeletal framework alone would not be very helpful if not for its unique respiratory system that allows a bird to beat its wings several times a second on the average and fly on average more than 10 hours straight – in the sun, without any protection, without getting tired. A human in great physical shape would collapse after 20 minutes of the equivalent exertion.
Bird accomplish that through a unique breathing process. When humans breathe in, we inhale oxygenated air. When we breathe out, we exhale deoxygenated air. We can’t simultaneously inhale oxygenated air and exhale deoxygenated air. We fatigue when we exercise, since our muscles lack the necessary oxygen to function properly. When birds inhale, half the oxygen goes immediately to the lungs, like us, and half the oxygen goes into something like a reserve tank. When it exhales, it has a system that sucks in this extra air in the “reserve tank” into the breathing tubules of the lung, which enables the bird to obtain oxygen during both inhalation and exhalation.
No other mammal can do that! Our blood and organs can’t obtain oxygen at the same time we exhale oxygen. But birds can flap their wings vigorously for hours and hours without getting fatigued because of their unique respiratory system.
Not only are the bird’s skeleton and biological systems a highly coordinated series of complex parts geared toward flight, but even something as seemingly simple as its feathers are. In truth, feathers are anything but simple. One “simple” feather can contain a million individual parts.
A feather’s overall structure is supported by a hollow shaft that runs up the center. Then, branching out diagonally from the shaft, hundreds of strands called barbs give a feather its flexibility and aerodynamic shape. Seen close-up, each barb supports hundreds of even smaller structures called barbules. Barbules are arranged in two sets of opposing pairs. Those extending from one side of a barb support a cluster of microscopic hooks and those on the other side are curled into ridges. As they overlap, the barbules interlock, hook-to-ridge, to create a zipper-like mechanism, and on a larger scale a herringbone pattern that blocks the passage of air bends freely and allows the bird to easily repair breaks on the surface of its wings.
Unless those individual components work together appropriately, the feather will not be functional. And feathers are just a small part of this combination of systems that allow birds to fly.
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If the flight of any bird is a wonder, an example of nifla’os haBorei, one very tiny bird is a wonder of wonders.
Hummingbirds – Poetry in Motion
In November 2011, Time Magazine honored a miniature aircraft as one of the best inventions of the year. It was designed to mimic a hummingbird in flight. Called the Nano Air Vehicle or NAV, it was developed by a team of engineers in southern California. This prototype of an experimental surveillance drone was equipped with a video camera and could hover, rotate and fly in any direction. It was hailed as a sensational piece of engineering, especially considering that all the parts were encased in a package that weighed about the same as an AA battery.
But in terms of its complexity and abilities, the NAV was still light-years behind the bird that inspired its creation.
Hummingbirds are among the most breathtaking creatures on the planet. There are 343 recognized species today. They are often described as nature’s helicopters. Their acrobatic displays are powered by wings that can beat more than a hundred times a second and are unparalleled in the avian world. The tail is a balancing organ that helps guide which direction they want to go. They can raise it to zoom up. They can drop it to stall. They can use it to go side to side. The flight muscle in a typical hummingbird represents about 43% of the body mass. It gives them a tremendous power to do the kinds of maneuvers most birds cannot even dream of accomplishing.
Hummingbirds routinely employ three specialized types of flight – forward, backward and hovering. To fly forward, the wings flap rapidly up and down, generating thrust. To hover, their angle and movement are radically adjusted to create a figure-eight pattern that stabilizes the bird’s body in the air as it feeds. To fly backward, the wings move in a circular path above the bird’s head.
No other bird can fly like this because no other bird has a skeletal system designed to function like hummingbirds. In virtually every other species of bird, the mechanics of powered flight are similar. Its wings flap up and down like paddles on hinges, creating lift only on the down stroke. While a hummingbird hovers, however, it flaps its wings backward and forward to generate lift on both strokes.
Hummingbirds need to hover in a fixed position, meaning that they need lift all the time. Their shoulder joint provides a unique solution to the problem. It can rotate a wing 140 degrees by twisting the upper arm bone. When the bone twists, the entire wing inverts as it’s coming back up to generate part of the lift that they require to maintain their stability in the air.
The hummingbird’s rigorous lifestyle is also sustained by its muscular, metabolic and circulatory systems. To keep this massive flight muscle filled with oxygen carrying blood, the bird’s heart has to beat as many as 1,250 beats a minute. All of this is being controlled by nerves firing at an incredible rate. To make this possible, the hummingbird is fueled for flight by consuming more than twice its body weight in nutrients each day. During its waking hours, the bird eats every 10 to 15 minutes. It has been estimated that to survive, an adult human being with comparable metabolism would require 150 pounds of food every 24 hours!
No Simple Tongue
The engineering demonstrated in the bird’s anatomy is again ingenious. But other parts of it are not less so.
The hummingbird’s tongue is about twice as long as its beak, so it can reach deep into a flower. Until recently, many scientists believed that the birds relied heavily on capillary action to draw the nectar through their tongues and into their mouths, kind of like water spontaneously rising up a thin straw in a glass. But some fascinating discoveries of the University of Connecticut have shown that the mechanisms involved are much more dynamic than anyone realized.
The hummingbird’s tongue is actually a nectar trap equipped with a pair of narrow tubes that taper sharply. The tip of each tube is segmented into a row of flaps that are attached to a supporting rod when the bird isn’t eating. These flaps form two rows of closed loops that fit compactly into the mouth. But when the hummingbird feeds, its tongue undergoes a dramatic transformation. Inside the flower, the tongue extends to make contact with the nectar. When immersed in fluid, the tip splits and the flaps on each systematically unfurl like a fork. Then, as the tongue is withdrawn, the flaps close tightly to seal and capture the nectar.
For delivery into the bird’s mouth, this entire process is executed automatically in less than a 20th of a second thousands of times a day from flower to flower to flower to flower.
The incredible workmanship of the hummingbird body and mechanics aside, the wonder of a hummingbird almost transcends language. Seeing it is almost like responding to the work of an artist, as one scientist put it. We respond with our soul, with our emotions. What can you say? Words can’t do it justice. You just stand there and applaud.
Murmurations of Starlings
On a January morning in southern England, flocks of European starlings depart from the heath, an area of open uncultivated land, where they had roosted throughout the previous night. In an explosion of motion and sound, the birds disperse to the surrounding countryside, where they will feed throughout the day. Twelve hours later, each will return to take part in one of nature’s most spectacular displays.
Late in the afternoon, small groups of starlings begin their journey back to the reeds and marshes that sheltered them the night before. Starlings are long-distance daily commuters. They will travel up to 30 miles to get to their chosen roost. They follow invisible aerial corridors, snaking through the countryside, avoiding the turbulence that is going to slow them down. They all come together to stay warm and safe in a large group.
As daylight wanes, small clusters become enormous flocks called murmurations, a word related to “murmur” and possibly derived from the sound made by half a million beating wings. Up to 300,000 individual starlings gather in the air all in one flock. They’re intelligent birds checking out the roost site to make sure that there are no predators, such as birds of prey or foxes, around.
After completing their initial survey of the heath, the flocks gather for the final time. Like a massive organism, they flow gracefully through the twilight sky. If a hawk or falcon approaches, it is often confused and driven off by the sheer mass and movements of the flock.
It’s hard to believe how so many birds don’t crash into each other as they twist and turn. The sky almost goes black with the density of the flock. Then, with a roaring noise in the air, suddenly they rain down like giant black hailstones. It is an astonishing sight.
Starling Air Traffic Control
This magnificent phenomenon evokes an obvious question: How do so many birds avoid collision while maintaining such precision in the air? Though much of the science behind these murmurations is still unresolved, recent studies in Italy and the United States have produced at least a partial explanation. Scientists photographed portions of a flock from two angles. Then they used the data to identify the locations of individual birds. They were able to plot the positions of more than 1,300 starlings within a murmuration and create 3D models to reconstruct their movements.
Research appears to indicate that an individual starling cannot monitor the entire flock. Instead, they’re estimating the distance between themselves and the nearest birds in their immediate vicinity, those to their left, right and especially in front of them. Each starling monitors only the positions of the six or seven closest birds and appears to follow one simple rule – when your neighbor moves, so do you. As a result, the slightest change of direction by one starling can trigger a chain reaction that ripples throughout the entire flock, creating constant variation within these immense formations.
It’s like fighter pilots flying in tight formations, where they can be wingtip to wingtip as close has 18 inches away. They’re using a property called topological distance, where the individual pilots aren’t actually monitoring the whole formation. Instead, they’re watching their nearest neighbor and responding to every movement he makes in the air. The aerial maneuvers of 200,000 starlings are even more demanding. The birds must each sense and react to the oscillations of the flock in less than 100 milliseconds, about three times faster than the blink of an eye. Their instinctive decisions are flawless.
It is a ballet, the choreography of which science is not close to understanding fully. For instance, the murmurations are three-dimensional. The flock moves in several directions at once, but there doesn’t seem to be a specific leader. Who decides whether to turn left or right or to form a giant sphere or a jumping lion in the sky? Who sends a message that it’s time to dive back into the reeds for the night? And how is it transmitted to hundreds of thousands of birds in an instant?
Unanswered questions may haunt scientists but only add to the wonder of these creatures.
747s and Birds
Flight is a complex function, with all the associated anatomy and behavior. The physical demands on a flying bird are severe and dozens of biological systems are designed to meet every challenge. The enormous quantities of energy and strength the bird requires are produced by hearts that beat more than 500 times a minute, massive breast muscles that relentlessly power their wings, the most efficient respiratory systems in the animal kingdom and digestive systems designed to fuel high metabolisms without taxing the stringent weight requirements of flight.
Birds also depend upon navigational systems that contract the sun, the constellations and the Earth’s magnetic field, an internal gyroscope to stabilize the orientation of their bodies during rapid movements in the air, acute vision to identify food from half a mile away, and a battery of instincts that cue and direct migration journeys across oceans and continents.
Many different but perfectly coordinating systems are necessary for the bird to fly. The more systems and component parts involved, the more challenging it is for scientists to explain how all of them came together so precisely in a bird. As one of them explained, “If you throw all the parts for a 747 into the middle of a room, turn on a fan and blow everything around, you’re not going to end up with a 747. Living organisms are much more complicated than a 747, and they are integrated wholes, not merely the sum of their parts. They are alive and responsive.”
We see birds flying all the time, yet most of the time we take them – and the miracle they represent – for granted. That’s a shame. Each bird is an opportunity to strengthen our emunah. Rav Avigdor Miller writes (A Nation is Born 8:18) that just as the miracles that Hashem performed in Egypt “were wondrous demonstrations of Hashem’s deeds, so are all the ‘natural’ processes and all events and even all objects demonstrations of Hashem’s deeds… Seeing is a miracle, hearing is a miracle, thinking is a miracle, eating and digestion are miracles, the birth of a child is a miracle, an enzyme is a miracle, DNA is a miracle, a chromosome is a miracle, and an atom is a miracle.” A bird is also a miracle.
Each bird in flight is a consummate blend of beauty and functional design that embodies the highest levels of engineering. Each is a tapestry of the mysterious and the unexpected, a showcase of behaviors that can surprise inspire and fill a human heart with awe and wonder. In short, a miracle. Let’s stop a moment to appreciate the miracle and not just let it fly by…
In the lush rainforests of Australia, birds roost in the low branches and amble across the forest floor enjoying the shade and tropical fruits, but the jungle isn’t theirs alone. A dingo (a dog-like predator) is prowling in the shadows and fruit won’t satisfy its appetite. All the birds can fly to safety except one – the cassowary, which can’t clear the ground on her puny wings. Though cassowaries may be flightless, they’re not defenseless. These huge birds are extremely aggressive. Instead of fleeing, it attacks, sending the dingo running for cover with one swipe of her razor-sharp claws.
The cassowary is one of approximately 60 living species of flightless birds. These earthbound avians live all over the world, from the Australian outback to the African savannah to Antarctic shores. They include some species of duck and all species of penguin, secretive swamp dwellers, speedy ostriches, giant emus and tiny kiwis.
Flight can have incredible benefits, especially for escaping predators, hunting and traveling long distances, but it also comes with high costs. It consumes huge amounts of energy and limits body size and weight. A bird that doesn’t fly conserves energy, so it may be able to survive on a scarcer or less nutrient-rich food source than one that flies.
Flightless birds, even those without the cassowary’s aggressive nature and razor-like claws, have their own means of survival. Emus and ostriches may weigh hundreds of pounds, much more than wings can lift, but their legs are thick and their feet sturdy, and their developed thigh muscles make them formidable runners. They may be flightless, but they can really wing it.