The majority of the 580 species and sub-species of hummingbirds are tiny—under four inches in length.
The hummingbird cannot walk (it uses its feet for perching), so it has to fly to get about.
The smallest bird in the world is the Bee Hummingbird (Mellisuga helenae) found in Cuba. It measures only 2.24 inches (5.7 centimeters) from the tip of its bill to the tip of its tail, and weighs but a fraction of an ounce (0.056 oz. or 1.6 gram).
Most birds are, aerodynamically, the most perfect flying machines on earth. The hummingbird, in addition, is the only perfect HELICOPTER.
His wings are attached to his shoulders in such a way that he can poise motionless in the air, and he can fly in any direction, forward, sidewise, up, sown—and even backward, a feat no other bird can do. (Coronet Magazine)
"While hovering, a ruby-throated hummingbird beats its wings up to 75 times PER SECOND."