This is more than likely a male, Red-winged Blackbird that got separated from his flock. In the winter, they will hide their red "epulates" which they display to impress the females and claim territory during breeding season. Normally, the bit of yellow is showing, but I did have a male last week who completely hid his wing color.
I had some Redwing Blackbirds on the feeder today. They are bigger than this bird was and the wing epulates were there. Some were yellowish and some were already red. Sorry I do not have a better picture.