Quiscalus quiscula
Unfortunately for the smaller birds, the Grackles have learned how to get seeds from the feeder. It's not easy, because they barely fit on the small perches, often falling off to one side, and flapping their wings to keep their balance, like this fellow is doing. Actually, they don't eat that much -- the House Finches they scare off are messier eaters -- but they do displace the other birds who have to fly off to some nearby tree and wait for the Grackles to have their fill. That's partly why I don't mind them too much, because I much prefer to take pictures of those birds while they are away from the feeder.