One last bird question for tonight. When I first saw this scaup, I thought the shape of the head looked like a Greater Scaup (much more broadly rounded than I associate with Lesser Scaups). However, when it flapped its wings, I saw the white did not extend out on to its primaries.
In this case, which is more diagnostic, the shape of the head or the extent of the white on a bird’s wings? What other characteristics might I be able to consider with this lone bird?