Flying birds are compact, well-integrated flying machines capable of producing the large amounts of energy necessary for flight. Their powerful wings are properly shaped to utilize the physical principles of moving air. In addition, the wing size and shape varies with species, according to the size of the bird and its speed and type of flight. In fact, birds can often be identified by their characteristic flight pattern.
The feathers of a bird serve to streamline the body for flight and provide the primary flying surfaces. The precise position of each feather is monitored by sensory receptors and controlled individually by tiny muscles to change shape and position in response to varying air pressure. Feathers are stronger by weight than any man-made substitute. They are intricately constructed and consist of a strong, flexible shaft (the quill or rachis) and a flat vane. The vane is made up of many filamentous barbs which are held together by tiny barbules. These in turn bear flanges and hooks, which act as a “zipper” to form a tight, flying surface.
The bones of a bird are lightweight, flexible and strong. Typically they are hollow and thin, with most of the bone substance at the outside of the bone for support. Some have internal struts and trusses for additional support. The size and shape of various bones are also suited for flight. Strong flying birds typically have a large keeled sternum (breastbone) that provides sufficient area for attachment of the large breast muscles required for flight.
The internal organs of birds are also suited for flight. Birds have very efficient respiratory and digestive systems, capable of processing large amounts of food and releasing an unusually high percentage of the energy locked in that food. They have well-developed circulatory systems and large, strong hearts for rapidly transporting food and wastes. Special air sacs, extensions of the respirator system, enter the limb bones of many species and provide extra buoyancy and added surface area for respiration and cooling. All of these factors work together to produce a system that is highly efficient and intricately coordinated.
Isn’t it ironic that so many scientists acknowledge design and creative intelligence in the production of airplanes and yet believe that the fantastic precision and coordination seen in flying birds are the result of “lucky” mistakes (mutations)?
Originally published in the Sept/Oct 1985 issue of Think and Believe