Posted by Gary W. Potter (198.81.23.73) on December 22, 2001 at 12:07:46:
A couple of additional comments:
1. In my earlier post I want to clarify that my lack of experience with Scaup was "summer" not "supper" scaup. Thanks to my duck hunting brother I have had supper Mallard, Pintail, and Teal, but never scaup!
2. After reading other posts and checking some references my confidence on the female being a Greater has gone up, mostly on basis of the post auricular crescent.
3. One more point concerning the lower female, which I think points toward Greater. I have noticed when seeing both species together, that the larger nail on the bill of Greater is usually distinctly visible from the side of the bill as seen in profile, while on lesser it is, at best, very difficult to see the nail on the side of the bill tip. I do not know how variable this characteristic is, but on the lower female, even with the tip of the bill cut off at the edge of the photo, the black does appear from the side, pointing toward Greater along with the head shape and eye color.