Thanks for clarifying the differences between these guys and buffleheads; I walked a golf course here in southwestern Ontario today and although I could see them quite well with my binoculars, they were indeed skittish and I could get nowheres close ... once I saw the bald eagle, I knew why !! Turns out I was right to question the bufflehead idea; they were definitely goldeneyes !!
Thanks MB. Excellent summary. You forgot to mention that their colloquial name is "whistler" from the whistling sound made by the quick beat of their wings in full flight.