References
•Birds of North America
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•Sibley, D. 2000,The Sibley Guide to Birds
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•Bent’s Life Histories on line
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•USGS Patuxent WildlifeResearch Center
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•HMANA Eastern Raptor Migrant Guide
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•Hanging Rock Raptor Observatory, W. VA
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•Dunne, P. Sibley, D., Sutton, C. 1988, Hawks in Flight