Sources
Birds of Eastern and Central North America (Peterson Field Guides) by Roger Tory Peterson
http://animals.nationalgeographic.com/animals/birding/american-crow?source=A-to-Z
http://www.allaboutbirds.org/guide/American_Crow/id
http://www.birdhouses101.com/Crow.asp
http://animals.nationalgeographic.com/animals/birding/american-crow?source=A-to-Z
http://www.allaboutbirds.org/guide/American_Crow/id
http://www.birdhouses101.com/Crow.asp