Donald S. Heintzelman – författare

There are forty species of hawks in North America, including vultures, the California condor, and the bald eagle, our national bird. Heintzelman's monumental study is a comprehensive survey of what we know about the migrations of these magnificent birds in North America, Central America, and the West Indies. After a general introduction on migration season, speeds, and methodology, eleven detailed chapters survey migration routes and statistics in all the following regions: eastern and western Canada, the Great Lakes area, New England, the Middle Atlantic states, southern Appalachia, the Gulf Coast, the Central states, Western states, Central America, and the West Indies. Subsequent chapters deal with the influence of weather systems and local weather variables, updrafts, thermals, altitudes and the daily rhythm of migrations, the influence of age and geography, and the role of hawk counts as indices to population trends.