Pick up a pair of owl feathers and rub them together, and you won’t hear much. That’s because the feathers are coated with a fine layer of plush fibers called “pennula,” which shroud sound and give owl wings that soft, velvety feel that Graham noted. An owl’s wing feathers separate slightly from one another in flight, so air flows over each feather, with the pennula providing a gap between adjacent feathers so there’s none of the friction or rubbing there is in most birds. The wispy vane fringes at the tips of both wings and tail also help to prevent wind eddies. Collectively, the serrated
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