I was watching a small white duck a little ways out on Green Lake this morning - all I could think of was smew(not likely, I know). To me, the black on the head appeared as patches behind the eyes, not as a cap. The only other non-white area was on the rump - streaky black/white/gray. Could have been primaries. I didn't get a close look and had no binos. Never thought of a coot...