Some 400 billion birds share the planet with us, each with its own abundant coat of feathers. Far, far too many to count. Perhaps even harder to fathom is the wealth of plumage colors, patterns and shapes that spring from Mother Nature’s artistry. Check out this mind-boggling variety of feathers.
Equally impressive is the story of how feathers evolved, how they grow on a bird’s body and the multitudinous functions they serve. They truly are marvels of engineering. Prepare to be wowed by the following 20 fascinating feather facts.
Birds are the only animals with feathers. Other creatures may fly (bats), lay eggs (lizards) and build nests (squirrels) like birds, but none are feathered. In that way, birds are unique.
Plumage didn’t start with birds. Scientists now believe that most dinosaurs also had feathers (or at least feathery fluff) including, if you can picture it, Tyrannosaurus rex. That means birds are actually modern-day dinosaurs. In the beginning, feathers were probably more for insulation or ornamentation than for flight. But as dinosaurs evolved into today’s birds, the role of feathers also evolved to help them soar.
Learn more about feathered dinosaurs in this video.
The number of feathers varies dramatically by bird species. In general, small songbirds sport between 1,500 and 3,000 feathers, eagles and birds of prey have 5,000 to 8,000, and swans wear as many as 25,000. Hummingbirds have the fewest feathers at 1,000, while penguins have perhaps the densest (warmest) feather coat with about 100 feathers per square inch.
Hummingbirds, like this green violet-ear (or Mexican violetear), have the fewest number of feathers in the avian world. (Photo: Mdf, Edited by Laitche/Wikimedia Commons)
Feathers can weigh more than a bird’s skeleton. That’s particularly true for flying birds, which have the lightest (mostly hollow) bones to keep them airborne. In some species, a bird’s skeleton represents only 5 percent of its total body weight, meaning their feathers account for a substantial portion of the rest.
Feathers share similarities with human hair. They’re constructed from the same fibrous protein called keratin (also the main component of nails, horns and claws), which pushes out of follicles in the skin. However, feathers are also clearly different. Unlike hair, they branch out into complex tree-like structures. The most intricate feathers have a central hollow shaft called the rachis, which sprouts branches called barbs, which further subdivide into smaller branching barbules. These interlock with other barbules to create a sleek, aerodynamic, form-fitting coat.
Birds maneuver feathers via tiny muscles in their follicles. These muscles form a network throughout a bird’s skin, allowing it to spread its feathers for a mating display, pull them closer together to form a tight seal against freezing temperatures, and fan its wing feathers to boost the surface area for better flight.
Tiny muscles in their skin follicles allow birds, like this wild male turkey, to puff out their feathers in magnificent mating displays. (Photo: Mark Gunn/Flickr)
Plumage comes in seven diverse varieties. Feather categories include wing feathers, tail feathers, contour feathers that cover a bird’s body and define its shape, filoplume (sensory) feathers, semiplume feathers that lie underneath contour feathers to provide some insulation, down feathers that offer even more insulation, and bristle feathers on the head that protect a bird’s eyes and face.
Feathers foster flight. Most of us take that for granted, but wing feathers truly are aerodynamic wonders. They’re perfectly designed — lightweight and flexible yet also rigid enough — to help birds lift off the earth, glide through the skies, dive at death-defying speeds, land expertly on flimsy tree branches, and pump continuously for thousands of miles during migrations. Each bird species has just the right feather array and wing shape for its particular flight needs.
Learn more about how feathers aid flight in this video.
Feathers do much more than help birds fly. Think of plumage as a multifunctional suit — a sort of rain coat, sunscreen, winter jacket, armor and fashion statement all in one. Feathers not only protect birds from the elements, thorns and insects, but they also repel water, provide camouflage and help birds attract mates with sexy, showy plume displays.
One bird species uses feathers to carry water. The male sandgrouse, a denizen of desert areas in southwest Africa, fills its specialized belly feathers with water from watering holes and transports it back to the nest for its chicks to drink.
Down feathers offer unparalleled insulation. These specialized feathers lie between a bird’s protective outer feathers and its skin to insulate against the cold. Down is constructed with flexible barbs that have long crisscrossing barbules. This creates a tight thermal layer that traps air molecules next to the bird’s warm body and retains heat while also being extremely lightweight. In fact, down is so efficient, ounce per ounce, that humans have yet to create anything better.
The longest tail feathers belong to onagadori cocks. These domestic chickens bred in Japan can sport tails up to 10 meters long (32 feet).
Check them out in this video.
Feathers get their colors in multi-faceted ways. One way is via pigments, three to be exact. One pigment — called melanin — produces black or dark brown feathers. Interestingly, feathers that contain melanin are stronger and more resistant to wear and bacterial degradation. Another pigment group called porphyrins (modified amino acids) produce red, brown, pink and green colors. A third group of plant-based pigments — called carotenoids — provide red, orange and yellow hues. In this case, color is added to feathers when birds ingest either carotenoid-containing plants or animals that have eaten them. Flamingos, for instance, get their pink color from eating algae and crustaceans that contain carotenoids.
Pigments aren’t the only color source for feathers. Some, like the iridescent throat feathers of a hummingbird, result from intricate patterns in the keratin of the barbules that refract light. Blue shades are produced by small air pockets in the keratin. The resulting patterns cancel out red and yellow wavelengths, allowing blue wavelengths to dominate.
A peacock’s blue and iridescent feathers don’t come from pigments but are produced by microstructures in the keratin that play light tricks. (Photo: Noel Reynolds/Wikimedia Commons)
The better the color and feather display, the better the chances for mating. It’s a hard-and-fast rule in the avian world. Studies show, for instance, that male house finches with the reddest feathers get more females. It’s hypothesized that bright colors may be nature’s way of indicating vitality and good health. Same for tail length. Research shows that female barn swallows (as well as many other bird species) find males with the longest tail streamers to be the most attractive. In the case of peacocks, male attractiveness is determined by a combination of iridescent colors, tail length and how enticingly they shake their display feathers.
At least one bird species sings with its wings. Male club-winged manakins rub specialized wing feathers together at super-high speeds like crickets. The vibration produces a violin-like sound called a stridulation. Its purpose? To woo the ladies, of course.
Watch and listen in this video.
Preening isn’t just about looks. Regular feather grooming actually serves many crucial functions. Preening keeps parasites in check, removes dirt, keeps feathers supple and allows birds to properly arrange their plumage for the most effective insulation, waterproofing and flight. The secret ingredient is a special protective oil produced in the preen gland near the base of a bird’s tail used to coat feathers. Some species like owls and pigeons don’t have this gland but rely instead on specialized feathers that disintegrate into a powder down that’s used to coat feathers in the same way.
A pied shag (native to New Zealand) preens its feathers to keep them clean, parasite-free, supple and waterproof. (Photo: Bernard Spragg. NZ/Flickr)
Flamingos use preen oil as makeup. Turns out the oil from their preen glands also pick up carotenoids like their feathers. Researchers have observed flamingos rubbing reddish-orange preen oil for extra dazzle on their already pinkish breast, neck and back feathers.
Birds replace their feathers regularly. It’s called molting, and it’s how birds deal with the normal wear and tear that gradually degrades hardworking feathers (even carefully preened ones). Depending on the species, birds may shed all their worn or damaged feathers or just some in a staggered fashion to make way for fresh new plumage. Molts typically occur once a year, but some species molt more often.
Birds aren’t the only ones that can replace feathers. So can humans, using an ancient technique called imping (short for “implanting”). This is particularly important for birds that break wing feathers in between molts. Not being able to fly for even a short period of time can be deadly. Imping allows damaged feathers to be snipped and replaced with similar ones from a previous molt or from a donor bird. The procedure involves inserting a thin piece of metal or bamboo (an imping splint) into the shaft of a broken feather still on the wing. Then a replacement feather is slipped onto the other end of the splint, and everything is secured with adhesive.
Check out an imping procedure in this video.