The Common Grackle is a bird found throughout Maine in the summer; but it migrates to the southern states for the winter. As is well described in the Birds of Maine field Guide, the male is a “Large [11-13 inches] black bird with iridescent blue black head, purple brown body, long black tail, long thin bill and bright golden eyes.” The female and juveniles are similar, but with duller coloring and smaller.
Female Grackle (2009)
A Grackle Altercation with Silent Arbiter (2009)
Male Grackle (2009)
Another observation worth quoting is from A Field Guide to the Birds of North America: “It is an opportunistic feeder and will eat almost anything, from grain to insects to fish, eggs, fledgling birds, and mice. It will wade into water, visit feeders, and follow agricultural vehicles in its search for food.”
See references in Birds.