Koguba-leek is the song of the Common Grackle. Seriously! He also says a loud cluck when calling. I'm just sure this is made for TV stuff.
The Common Grackle Quiscalus quiscula is long (over 12 inches) and has pale yellow eyes. They appear all black at a distance but in good light, males show iridescent glossy purplish/blue/green head, neck and breast. Females are smaller and have a duller color than the males. That's the norm for the bird world. They have a longer tail and beak than other blackbirds.
Even though I seldom see more than one at a time at our feeders in the winter, they are considered abundant and gregarious (yep TV sitcom calling). Typically they roam in mixed flocks in open fields, marshes, parks, suburban areas.
The female lays 5 pale blue eggs, with black scrawls, in a bulky stick nest lined with grass. It's placed anywhere from low in a bush to high in a tree. Some nest in colonies.
They range from the southern states to upper Canada - never on the west coast. This fellow may be passing through on his way south.
Their diet is extremely varied, including insects, crayfish, frogs, mice, nestling birds, eggs, grains and wild fruits. At feeders they are especially attracted to cracked corn. And therein lies why he was feeding under the squirrel feeder.