Hummingbird gets their name from they make some sounds like hum. Recently on the web some scientists reported they got the similar sound from vibrating their feathers so hummingbirds might not sing from their vocal region but from their feather. Hummingbird is a very small bird. They range from 5 to 22 cm in length weighing 2 to 25 g depending on its different species. Their wings can flap 15-80 times per second, though I thought it could be higher (I used 1/500 second and could not get solid wings in the picture). They could hang in the mid air by flapping their wings. They could fly backwards, this is the only species of birds which can do so. They eat their food weighing more than their body weight a day. Some species of hummingbird has a heart rate of more than 1000 pulse per second. A male hummingbird has bright color in the neck. Their lifespan is about 3 to 4 years, though there are some records showing 12 years. On the pitures shown here, they might be from 3 or 4 different species of hummingbirds. See more in wikipedia.org/wiki/hummingbird.