One of the most amazing creatures in the world is the tiny hummingbird. It's unique even among birds. The smallest birds hummingbirds and the smallest hummingbird, the 5-cm bee hummingbird, weighs less than a penny (2.5 g). Hummers are the only birds which can fly backwards, and they can do so at speeds exceeding 34 mph.
They're indigenous only to the western hemisphere and most diverse in the South American Andes where there are about 160 different species, but only a single breeding species can be found in eastern North America.
They're known as hummingbirds because of the humming sound created by their beating wings which flap at high frequencies audible to humans. They hover in mid-air at rapid wing-flapping rates, typically around 50 to 80 times per second.
Hummingbirds have the highest metabolism of any homeothermic animal. To conserve energy when food is scarce, and nightly when not foraging, they go into torpor, a state similar to hibernation, slowing metabolic rate to 1/15th of its normal rate.
Hummingbirds consume more than their own weight in nectar each day, and to do so they must visit hundreds of flowers. They're continuously mere hours away from starving to death and are able to store just enough energy to survive overnight. They supplement the nectar on which they feed with small insects.
The video below illustrates a fascinating feature of the hummingbird tongue which is much more complex than previously thought. It doesn't function like a simple wick or a soda straw but rather like a pump. It's pretty amazing: