Blackbird - white wing patches

Thank you. I have not seen this bird again since the initial siting. I will let you know if I do.

I saw a bird that looked a lot like this one at my bird feeder in Charleston (East Central Illinois) this morning, 5/2/18. How big is this bird? The one I saw was about the size of the House, Purple and Gold finches who eat at my feeder all of the time. This one wanted no company at the community trough and chased all the other birds away before eating his fill, alone. He was black with white wing patches that, when he was at rest, folded back to look like a white streak on his back. I have never seen any bird such as this anywhere in Illinois and I have fed birds in just about every part of the lower 4/5ths of the state.