These maps are from The Sibley Guide to Birds of Eastern North America by David Allen Sibley. Copyright 2003 by Chanticleer Press, Inc. Published by Alfred A. Knopf, a division de Random House, Inc. New York. Republished by permission from David Allen Sibley.
For more information, please visit: http://www.sibleyguides.com/about/the-sibley-guide-to-birds/
