This page has sources that helped me build this site.
Cornell and Audubon Bird Society www.birdsource.org/gbbc
Cornell University. www.birds.cornell.edu
Cornell University. www.allaboutbirds.org
Widdop, Linda. www.phillybirdnerd.net
Sibley, David.The Sibley Guide to Birds of Eastern North America. New York, New York. Andrew Stewart Publishing edition.
Tekiela, Stan. Birds of Pennsylvania 2nd ed. Cambridge, Minnesota. Adventure Publications Inc.
www.npwrc.usgs.gov
Cornell University. www.birds.cornell.edu
Cornell University. www.allaboutbirds.org
Widdop, Linda. www.phillybirdnerd.net
Sibley, David.The Sibley Guide to Birds of Eastern North America. New York, New York. Andrew Stewart Publishing edition.
Tekiela, Stan. Birds of Pennsylvania 2nd ed. Cambridge, Minnesota. Adventure Publications Inc.
www.npwrc.usgs.gov