Sources
Birds of Eastern and Central North America (Peterson Field Guides) by Roger Tory Peterson
http://animals.nationalgeographic.com/animals/birding/common-grackle?source=A-to-Z
http://www.allaboutbirds.org/guide/Common_Grackle/id
http://www.squidoo.com/commongrackle
http://animals.nationalgeographic.com/animals/birding/common-grackle?source=A-to-Z
http://www.allaboutbirds.org/guide/Common_Grackle/id
http://www.squidoo.com/commongrackle