The smallest and most beautiful of all birds, found only in America, and almost exclusively tropical. They get their name from the peculiar humming noise made by the rapid vibration of their wings. The muscles of their wings are very strong. This enables them to fly with great swiftness, and to hover over a flower while they capture the minute insects in it and perhaps sip the nectareous juices. They do not sing, having only a kind of shrill chirp. Their nests are very pretty, made of mosses and lichens, and lined with cotton and any soft thing they can find. They are unsurpassed by any birds for their brilliant plumage, and some are ornamented with crests, tufts, or frills. Many fruitless attempts have been made to domesticate these beautiful birds.