Kirk Keever, age 9, of Winchester, Indiana for his question:

How can a hummingbird fly backwards?

A hummingbird is double, jointed, at least in his shoulders. He weighs only about one ounce and almost a third of his weight is flying muscles. With these mighty little muscles, plus his swivel shoulder joints, he can beat his wings 70 times a second  ¬while flying forward or backward or hovering in one spot. Most birds flap their wings up and down. So does the hummer, but he swivels his shoulders with each wing beat. Each beat has a forward stroke and a backward stroke. The forward stroke moves over and down, with the front edge of his wings leading the way. Then his shoulders swivel in a quick half circle. The front edge of his wings now face backward. The backward stroke moves the wings up and over to start the next beat.

Like all birds, he beats the air to form cushions and streaming currents. His wings move the air and the moving air moves him. When he changes his swivel pattern slightly, the air currents change and move him in a different direction. With slight changes in his backstroke, he can fly forward or backward or build air cushions to hold him just where he is