Pipzi
The Tiny Birds That Hover
If you have ever watched a hummingbird at a flower, you may have wondered how it stays so still in the air. Most birds must keep moving forward to fly. A hummingbird, however, can hang in one spot, drink from a blossom, and then dart sideways or even backwards. This rare skill is called hovering, and it depends on the special way these small birds use their wings.
A pigeon or a sparrow flaps its wings mostly up and down, and the downward push does nearly all of the work. A hummingbird's wing works differently. Its shoulder joint lets the wing turn almost upside down, so the wing traces a flat figure-eight shape in the air. Because of this twist, the wing pushes air downward on the forward stroke and again on the backward stroke. The bird gets lift in both directions, which lets it stay in place like a tiny helicopter.
The wings also move astonishingly fast, beating dozens of times every second. That is why they look like a blur and why they make the soft humming sound that gives these birds their name.
Hovering is hard work, and it uses a great deal of energy. To keep going, hummingbirds visit many flowers each day and drink sweet nectar, which gives them quick fuel. They also catch small insects for protein. Their hearts beat very quickly, and their bodies burn food at one of the fastest rates in the animal world.
At night, when they cannot feed, many hummingbirds save energy by entering a state called torpor. Their body temperature drops and their breathing slows, almost as if they were switched to a low-power mode. In the morning they warm up again and return to the flowers.
Hummingbirds live only in the Americas, from Alaska to the southern tip of South America. Wherever they are found, they remind us how much clever engineering can fit inside a very small body.
