Tuesday, September 1, 2009

Bird Flight

Nature Watch
By Susan Benson,
CNHM Director of Education

The robins are back again. For the past two days, large numbers have been weighing down the trees in the Museum’s outdoor classroom. Robins flock together for feeding and for migration, so I imagine they are getting ready to instead of “raid the frig” they are ready to “raid” the mountain ash berries. Watching them flutter and fly is such an enjoyment. Have you ever wished you could be a bird for just one day, just to feel what it is like to fly? Bird flight is an amazing adaptation!

The wing of a bird consists of two functional parts: an inner part nearest the body and the outer hand. The outer hand, with its pliable flight feathers, functions as a propeller. The inner part provides the bird almost exclusively with lift.

All birds, except the hummingbird, move their wings at the shoulder, elbow and wrist. The entire hummingbird wing is a “hand wing,” or propeller. It does not soar or glide. Since the hummingbird moves its wings solely from the shoulders, it has great maneuverability in the air. The wing is extended throughout the whole stroke, making a figure eight and producing lift on both the up- and down-stroke. With this beat many hummingbirds can beat their wings fifty-two times a second.
Gliding is the simplest form of flight, when a bird’s wings make no propulsive movements. It is actually coasting “downhill” in reaction to air currents. Larger birds such as the albatross, condor, vulture, eagles and storks minimize their use of energy while gliding.
A soaring bird is one that maintains or even increases its altitude without flapping its wings. There are three main requirements to soar successfully: large size, light wing-loading, and maneuverability. Many birds that use soaring as a flight technique have deep slots in their wings to decrease drag and aid their take-offs.

Birds may stay aloft by riding rising warm air current called thermals, or by obstruction currents, which are updrafts of air caused when steady winds strike and rise over objects such as mountains, hills, buildings, and sand dunes.

Many birds hover by flapping their wings sufficiently to hold their position over one point on the ground. A hawk or kestrel does this by beating its wings, depressing and spreading its tail feathers, and holding its body at a nearly vertical position. They can hover for longer lengths of time by flying into a headwind, allowing them to stay stationary.

Much of our human flight was created through the intense observation of birds in flight. We learned from their streamlined bodies that help them overcome air-resistance. We discovered their hollow bird skeleton used to reduce weight, and the large keel of their breastbone. Most of all, they give us much entertainment and enjoyment.
For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.

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