Listen to the sound of the Common Grackle here: -- http://www.birds.cornell.edu/programs/AllAboutBirds/BirdGuide/Common_Grackle_dtl.html#sound

"The Common Grackle is an opportunistic forager, taking advantage of whatever food sources it can find. It will follow plows for invertebrates and mice, wade into water to catch small fish, and sometimes kill and eat other birds at bird feeders."

"The Common Grackle commonly engages in anting, allowing ants to crawl on its body and secrete formic acid, possibly to rid the body of parasites. In addition to ants, it has been seen using walnut juice, lemons and limes, marigold blossoms, choke cherries, and mothballs in a similar fashion." -- All info from Cornell Orthinology website