One of the most interesting creatures in all of creation is the hummingbird. It’s the smallest bird with some weighing as little as .06 ounces (1.8 grams) -- smaller than some moths. Hummingbirds are interesting not only because of their ability to hover and their incredibly small size, but because of the intricate energy system they have. How can such a small bird survive while expending such an incredible amount of energy?
Hummingbirds are energy dynamos. These tiny birds burn 10 times as much oxygen per gram of body weight as does a human being. Their heart will beat up to 1200 times per minute compared to a human heart which in exercise might reach 110 to 120. In order to eat, hummingbirds have to hover, which burns energy at an incredible rate. During hovering their wings are beating 15 to 80 times per second!
The most significant problem for the hummingbird comes at night when the bird has to shut down its metabolism. At the rate at which it burns energy during the day it would not have enough energy to survive through the night at its normal body temperature. A hummingbird that does not store enough food energy to meet its needs for the night will die in its sleep.
What the hummingbird does is to lower its body temperature and take in up to 100 times less oxygen at night than during the day. In this way it uses only a fraction of its daytime energy. This means that the bird has a very difficult time waking up in the morning -- especially the smaller species. Raising the body temperature back to daytime level can take up to 20 minutes.
There are many design features involved in this process in order for the bird to survive. The hummingbird is a remarkable demonstration of amazing design for a very specific and unusual form of life.
Science Digest, August 1988, page 8
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