You can free download Birds Their Structure and Function 2nd Edition in pdf format.
About Book
A general introduction to avian anatomy. Special coverage includes a detailed account of the external features essential for the identification and description of birds, as well as discussion of flight at great altitudes over immense distances, navigation, sight, and hearing. The overall result is a concise and authoriataive text covering wild and domestic birds–an invaluable reference source for all interested in ornithology.