The hummingbird is an animal that by all rights shouldn't be able to fly. Its wing movements are not at all like that of other birds. But not only can they fly, they're so good at it that they're the only species which can fly backward. They're also one of the few--but not the only--that can hover. And in the past week alone, two new studies on hovering animals have been made public. One is on bats and the others on the bluegill sunfish.