Crissy Hunter, age 11, of Superior, Wis., for her question:

DO HUMMINGBIRDS MIGRATE?

Bird experts believe that the hummingbird originated in northern South America. He can now be found throughout South America, Central America, Mexico, in some of the eastern and Western parts of the united states and in southern Canada. the birds beat their wings so fast in flight that they produce the humming sound that is responsible for their name.

There are 319 species of hummingbirds in the Western Hemisphere. Some migrate each year from South America to North America and back again while other members of the family are nonmigratory.

Those who make long flights stow up a thick layer of fat under the skin before they head for new parts. The ruby throated hummingbird, for example, will take on a fuel load before his flight that is almost 50 percent of his body weight.

Nonmigratory hummers do not build up fat reserves. It happens only to those who migrate and is caused by an endocrine stimulus triggered by the length of daylight.

Twice each year the ruby throat flies between his home in the tropics and the eastern part of North America, at times going nonstop 500 miles across the Gulf of Mexico. Scientists report and prove by metabolic tests that the ruby throat cannot possibly store enough fuel for such a long flight. But the birds have never read the report  so they continue to make the flights.

Hummingbirds never soar. They must depend on beating wings for flight.

The ratio between a hummingbird's wing surface and the weight of his entire body is about the same as the ratio in other birds that use flapping flight. Soaring birds have :pore wing surface per unit of body weight. With the hummer, however, his flying muscles are much larger in proportion to his size and weight than any other bird. The muscles are attached to a keel on the breastbone that is also proportionately deeper and sturdier than those found on all others.

The hummingbird's power lets the wings beat 55 times per second in hovering flight. No humming sound is heard at this speed. In level flight the speed increases to 75 beats per second, and the hum can be heard. During courtship, the male goes through a series of spectacular aerial gymnastics and the vibration of the wings goes as high as 200 beats per second.

A hummingbird's takeoff takes only seven hundreths of a second  and that's fast. His tiny feet are only used for perching. He can't take a walk or climb along a tree branch. If he wants to move to the right one inch, he has to fly that distance.

Hummingbirds conserve energy by going into a type of  nocturnal hibernation. At night their body temperatures drop about 10 degrees, thus saving energy.