Do you know what these birds are?

I can't take pictures of them at the feeder because they detect movement at the window and leave, no matter how sneaky I try to be.  They're ungainly and ugly, and stay in a flock.  I took pictures of them on the fence and the satellite dish and cropped them.  If you recognize them, let me know.  They must be very common, as many of them as I see.  Click on the pictures to make them a little bigger.

Thanks to Penny, I believe these are cowbirds.  It seems their reputation is as ugly as their appearance.  Stupid bad birds, eating at my feeder.  Shoo!