Help identifying a black bird?

I saw a black bird on a lamp post making a sound a while ago that I think sounded more like a cat pur/ground squirrel/frog (except w/o change in pitch). I think it was bigger than the small black flying group of birds around this area and it didn't stand up straight like the cawing ones (more like a duck) oh and I live in the California Bay Area. Sorry for the bad description, but if anybody could give me some ideas I would be very appreciative.