Illustration of the booted racket-tail, Ocreatus underwoodii, is a species of hummingbird. It is found in the Andean cordillera of Bolivia, Colombia, Ecuador, Peru, and Venezuela. All hummingbirds depend on flower nectar to fuel their high metabolisms and hovering flight, which is illustrated by the bird at the bottom.
Hummingbirds are New World birds that constitute the family Trochilidae and they are among the smallest of birds. They have become popular among people far beyond birdlovers due to their tiny yet resilient body, and colourful beauty.
The name hummingbird relates to 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 times per second This makes them capable to fly at speeds exceeding 15 m/s, and doing it backwards.
Hummingbirds have the highest metabolism of any animal.To conserve energy when food is scarce, and during the night, they go into torpor, a state similar to hibernation, slowing metabolic rate to less than 10% of its normal rate, which is illustrated by the bird in the middle of the picture. The top bird is simply trying to keep its fantastic wings clean.