We take many things for granted without realizing the complexity of their design. That is undoubtedly true of bird feathers. American biologist Thor Hanson correctly wrote that feathers are “complex structures of ingenuity that defy the most advanced human technologies.”
Feathers are made of keratin, which is a protein. They are connected to blood vessels like our hair is connected to our vascular system. Once a feather reaches its final stage, it is disconnected from the blood vessel that has nourished it, reducing the weight of the feather. When molting occurs, and old feathers are discarded, the vascular system is re-connected by tiny muscles surrounding the feather follicles to grow a new feather.
These same muscles allow a bird to move its feathers for various purposes. Feathers serve the bird by providing insulation, waterproofing, color, display, and flight. Birds accomplish each of these functions in remarkable ways. Peacocks can present colorful displays, but so can parrots, pheasants, and various tropical birds.
Feathers provide insulation by trapping air, which is a poor conductor of heat. Down feathers trap air efficiently while adding very little weight to the bird. This same feature gives waterfowl their buoyancy while giving them insulation. Birds preen their feathers by treating them with oil from a gland just above the bird’s tail. The tight interlocking barbules in a bird’s outer feathers make them impenetrable to water. Birds use down to produce an environment that allows eggs to hatch and to keep chicks safe. Modern technology can’t match the heat-to-weight ratio of feathers.
Flight is possible because each wing feather has the shape of an airfoil to provide lift and minimize drag. Since the feathers are flexible, they can move to reduce drag, and their tips are designed to minimize turbulence making smooth flight possible. They really are complex structures of ingenuity.
Color in bird feathers is accomplished in several ways. For some feathers, melanin gives color to the feather’s keratin, and the structure of keratin is such that the bird’s diet can control its color. A flamingo’s pink color comes from eating algae that have carotenoids in it. Rather than using pigments, many brightly-colored bird feathers use structural color produced by manipulating light waves to create blues, greens, and iridescent colors.
Considering the complex structures of ingenuity we know as bird feathers brings to mind Psalms 9:1, “I will praise you, Lord, with all my heart; I will show forth all your marvelous works.” Feathers are among those marvelous works.
— John N. Clayton © 2023
References: For more amazing information about feathers, see Thor Hanson’s book Feathers: The Evolution of a Natural Miracle, published by Basic Books © 2011, and Noah Stryker’s book The Thing With Feathers, published by Riverhead Books © 2014.