University of Michigan Museum of Zoology

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Welcome to basic bird anatomy and topography

What is a bird?

A bird is a warm blooded animal which is covered with feathers, lays hard-shelled eggs, and has wings for the front limbs. It has a four-chambered heart like mammals, but unlike them, has no teeth and has a specialized flow-through respiratory system with air sacs connected to the lungs. The anatomy exhibits many adaptations for flight.

wing anatomy


Bird skeletons show many adaptations for flight, the most important being the reduction in bone, including hollow bones, as a way to cut down on weight.


Feathers are unique to birds. They are very complicated structures which primarily serve to make the bird aerodynamic, as well as keep it warm and dry.

Please note: It is not legal for individuals to have native birds, eggs, nests, feathers, or any parts in their possesion without permits from the U.S. Fish & Wildlife Service, and their state Department of Natural Resources (except legally hunted birds). Museums, nature centers, schools, and other educational institutions may keep them.

Illustrations of skeleton and feathers after: Alfred M. Lucas & Peter R. Stettenheim. 1972. Avian Anatomy- Integument, pts. 1, 2. Agriculture Handbook 362. U.S. Government Printing Office, Washington, DC.

Recommended for further reading:

Austin, Oliver L. 1961. Birds of the World; a survey of the twenty-seven orders and one hundred and fifty-five families. Illustrated by Arthur Singer. New York, Golden Press.

Erhlich, Paul L. 1988. The Birder's handbook: a field guide to the natural history of North American Birds. New York, Simon & Schuster.

Advanced high school and college level:

Gill, Frank B. 1995. Ornithology. New York, W. H. Freeman.

Elementary level:

Zoo Books

For information and pictures of different kinds of birds, see the Link to bird biodiversity web pages.

Last updated 3 April 1998 by Janet Hinshaw.