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Engineers Are Racing to Harness the Dazzling Magic of Feathers. They Haven’t Solved the Mystery Just Yet
The natural marvels, which do everything from enabling acrobatic flight to insulating against Antarctic cold, continue to inspire new designs and technologies
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At the end of just about every commercial airliner’s wings is an important piece of technology that can be easy to miss. The small upturned tips of each wing are called winglets, and although they weren’t added to the big airliners until the late 1980s, they were invented more than a century earlier. Years before the Wright brothers’ historic first flight, a British engineer named Frederick Lanchester patented the idea of more efficient wings for his model gliders, tipped with the very first human-made winglets. His design took inspiration from one that evolved millions of years ago: the wings of eagles that flex their tips upward as they soar.
Birds have inspired human inventions for millennia. Japanese bullet trains have long noses designed to copy the beaks of kingfishers, and woodpeckers’ natural shock absorption could be borrowed for applications including protection of airplane black boxes. The more that designers, engineers and inventors study birds, and particularly their feathers, the deeper their appreciation becomes for these marvels of evolutionary engineering. Bird feathers can move or repel water, make or mask sound, create wondrous displays of color or impressive camouflage, all while maintaining a light weight, softness and warmth. This natural covering that birds have grown and used for millions of years is still, in many ways, superior to anything that humans can produce.
“There is no manufacturing technology that comes close to a feather,” says David Lentink, an engineer and biomimetics expert at the University of Groningen in the Netherlands, and co-author of an April paper on the function and structure of feathers in Journal of the Royal Society Interface.
Part of the gap between natural feathers and engineered materials comes down to scale. The best industrial 3D printers in the world can reliably sculpt at precisions down to about one hundredth of a millimeter. That sounds impressively small, and in the context of human engineering, it absolutely is. But a feather’s smallest functional structures, called keratin filaments, go down to the nanometer scale. That’s 10,000 times more intricate than our best modern manufacturing technology.
But the aspect of feathers that most impresses and inspires modern engineers is their ability to serve multiple functions at the same time.
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The most obvious function of feathers is flight. Strong but lightweight and soft, feathers allow most birds to catch the air and lift themselves off the ground. Birds can make short flights to evade predators or catch prey, or they can head out on thousand-mile seasonal migrations. Flight has allowed birds to spread to every corner of the world, and it has been inspiring inventors since long before Lanchester’s 19th-century winglets.
The ancient Greeks told the story of Daedalus and Icarus, a tragedy about the dangers of ambition. The inventor Daedalus makes wings of bird feathers for himself and his son, but when Icarus flies too close to the sun, the glue holding his wings together fails, and he falls to his death. Today, Daedalus’ wings would be classified under a category of design called biohybrids. Rather than trying to recreate feathers from scratch, biohybrid designs incorporate actual feathers into otherwise synthetic machines. Lentink and other researchers use biohybrid drones to recreate bird flight more closely than ever before, and they have recently created a flying robot that can land on a branch like a songbird.
After flight, another obvious function of feathers is color. Every bird, whether it flies or not, uses this function. Some use color to stick out and attract mates, like peacocks and bright-red cardinals. Others want to hide rather than show off, as with the mottled brown plumage of many female ducks that lets them blend into their marshy nesting habitat or the song sparrow that uses its streaked camouflage to disappear into a twiggy shrub. Hummingbirds and many other species create dazzling iridescence thanks to layers of pigments in their feathers.
Those layers use a phenomenon called constructive interference, where two light waves reflecting off different layers create an effect that neither could achieve on its own. “That helps birds create these colorful, iridescent displays that can change color as you look at them from different angles,” says Sebastian Hendrickx-Rodriguez, lead author of the new paper.
Feather color is inspiring more than just beauty. Researchers are developing a new generation of more efficient solar panels, using another structural trick that causes the reflecting of infrared and ultraviolet light—based off the feathers of birds like arctic redpolls and snowy owls.
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Feathers also provide birds with vital insulation and temperature regulation. Downy feathers from birds like geese have been used by humans for centuries to make soft, warm materials. To this day, no synthetic material can match down’s ratio of weight to warmth, but insulating feathers continue to inspire new materials and technologies. Not surprisingly, penguins are often used as inspiration due to their adaptations to some of the harshest cold on Earth. Researchers are developing all-weather textiles that retain heat and repel water, while staying breathable, based on the triple-layer structure of penguin feathers. Others are experimenting with new polymer aerogel materials based on penguin feathers that could have applications for building insulation and climate control, showing the wide variety of applications that can be based on one particularly specialized group of birds.
Feathers also play a role in generating or eliminating sound. Hummingbird tails produce a bell-like trill when they dive, helping impress potential mates. The silent wings of an owl allow it to sneak up on mice and other prey undetected at night, which has inspired new methods for quieting aircraft, especially helicopters and rotor-powered drones.
Another impressive function of feathers, from an engineering standpoint, is how they function in contact with water.
“We all know that water rolls off a duck’s back,” says biologist Frank Muzio. “But all birds need to stay dry.” None of the other functions work right—the colors are muted, flight becomes impossible—if the birds get too waterlogged. Muzio was lead author of a 2024 study published in the Journal of Avian Biology, based on his PhD research, that reviewed water repellency in bird feathers.
The duck feather has received a lot of attention in waterproofing technology, recently inspiring a new type of gelatin film for food packaging that could be both more sustainable and keep food fresh longer than plastic. But to Muzio’s point, terrestrial birds use water repellency, too. Scientists have cited the iconic birds of paradise of Indonesia, Papua New Guinea and Australia as inspiration for a new evaporation technology that may improve desalination of seawater. Traditional evaporators don’t work well in wet weather, but this new material stands up much better to wetting and drying, just like the rainforest birds that inspired it./https://tf-cmsv2-smithsonianmag-media.s3.amazonaws.com/filer_public/79/ca/79ca7593-edd7-4b26-a2fe-faf311ba4923/gettyimages-978841734_web.jpg)
For all of feathers’ other wonders, what may be furthest ahead of our own engineering is their ability to self-repair. Although birds replace feathers, both on an ongoing basis and during annual molting, many feathers have the ability to recover from minor damage. Parts of a feather can come apart and reform into their original shape in a way that engineers can only dream of for their materials. Run your finger down the length of a flight feather, and the tiny barbs that come off its central vane will separate easily, but they then can be just as quickly smoothed back into order as if no disturbance had ever happened.
“This is very unusual,” says Lentink. “Think of an airplane rustling its wings a little bit and being fine again, after some critical failure in the surface.”
This self-repair mechanism is inspiring new designs of so-called soft electronics, like insulators and semiconductor parts. They may someday be able to reorganize themselves back into a working pattern after damage, just as pigeon feathers have done for millions of years.
One of the most remarkable aspects of all these functions is how they arise from a chemically simple material. Feathers are made of keratin, the same compound as our hair and fingernails. Across over 10,000 bird species, in forms as small as the bristles on a hummingbird’s forehead and as large as condor flight feathers, every feather in the world is made of this one substance.
“Our first instinct as engineers is often to change the material chemistry,” says Hendrickx-Rodriguez. “If we want to make a stronger iron, let’s add some carbon to make steel. If we want to color our plastic, add a chemical dye.” With a much more limited range of materials available to it, evolution works with what it has—keratin—and solves the problems facing the bird with new structures, rather than new materials.
“It’s really mind-boggling, if you look at the whole list of the things that feathers can do,” says Lentink. After thousands of years of marveling at feathers, humans still cannot recreate one. But as researchers understand more about feathers and all their functions, they will continue to take inspiration from this simple but ingenious evolutionary design.