Perched there, the robin shook her tail and fluffed up her body feathers before letting everything settle back into place. Then she began to preen, turning and dipping her beak to lift and comb individual quills and vanes, like a fussy housekeeper arranging and rearranging the furniture. I smiled, but who could begrudge her perfectionism? Those feathers impacted every aspect of her life. They protected her from the weather, warding off the sun, wind, rain, and cold. They helped her find a mate, broadcasting her femininity to any male in the neighborhood. They kept out thorns, thwarting insects, and, above all, gave her the skies, allowing a flight so casually efficient that our greatest machines seem clumsy in caparison. Abruptly satisfied with her plumes, the robin dropped from the branch and set off over the field, wings parting the air in quick, certain strokes. I lowered my binoculars, far behind the Audubon group now, but glad to have been reminded of a natural miracle, feathers, as common around us as a robin preening and taking flight.
-Thor Hanson, Feathers: The Evolution of a Natural Miracle