The other day, as I walked home from the post office, house sparrows were darting to and fro in the limbs of a tree. One was on the ground, pecking about in the dust and winter-bleached grasses. When I approached along the sidewalk, the sparrow shot straight up, a perfect vertical line, to a twig some twenty feet high in the tree. This took no more than a second. Although it's possible the wings fanned so fast that it wasn't discernable to my eye, I saw no flapping of wings. I asked, how'd you do that?! The sparrow gazed down at me like a proud little stuntman.