One of the challenging aspects of birding is the ability to identify and name the birds. We see many different species of ducks here in South Texas, and most are distinctive enough to identify with certainty. But there is a pair of ducks that have caused ID problems for a very long time: Greater Scaup and Lesser Scaup. With names like that you would expect one to be obviously larger or flashier, but alas they are almost identical! The Greater Scaup is slightly larger, but they are almost never seen together, so judging size is useless. Field guides give information like "Greater has a more rounded nape contour" and "Lesser has a taller and narrower head". Also, "Black nail on tip of bill averages smaller on Lesser, but there is much overlap". For these reasons, we have never positively identified a Greater Scaup, as they are rare in Texas.
While at the South Padre Island birding center a couple of weeks ago we spotted a lone Scaup resting with a group of other ducks. I got some good pictures, and it seemed correct for a Greater Scaup. The head was "more rounded" and the black nail on the tip of the bill was large"ish". But how to be sure?? During this visit we had talked with one of the premier birding experts in Texas, Mary Gustafson. So we took our camera over to Mary, showed her the pictures, and she confirmed that it was indeed a Greater Scaup. Sometimes you've just got to get an expert to help you out!!