Hummingbirds get their name from the quiet hum produced by their rapidly flapping wings, which flap at around fifty times a second, and allow them to fly faster than thirty-five miles an hour. Like their quickly beating wings, they have one the fastest metabolisms found in any animal. Their flight technique allows them to hover in a single spot mid flight to drink nectar from flowers. Furthermore they are the only animal that has the ability to fly backwards. They are very small with sizes 3 to 5 inches in length.