Aldo, our American Kestrel, has been very busy preening. Even in front of a group, he will tuck his head behind his wing to organize his fluffy down or twist his tail forward and pull his beak along the length of each feather. Birds preen constantly to keep their feathers “zipped” together so they remain strong for flight, stay waterproof, and keep the bird warm. Aldo will also do a good imitation of a dog shaking off after a dip in the lake when he shakes out all of his feathers. Instead of water spraying everywhere, a cloud of white dust puffs around him. This is an indication that he is going through a molt, or the annual dropping and regrowth of all his feathers. New feathers are protected by a thin, waxy sheath as they grow to prevent breakage. This sheath will eventually be pulled off by the bird while preening or it can break down on its own. These crumbled bits of sheath get stuck in the layers of feathers until he gives a good shake to send them flying. Occasionally a little downy feather pops out, too, and is carried away with the breeze.