Date: 10/28/18 10:27 am From: Joe Roller <jroller9...> Subject: Re: [cobirds] Re: Teachable moment. Please post your photos for study.
Although ducks do hybridize and Aythya hybrids, eg Ring-necked x Tufted Duck hybrids occur, the "structural features" Glenn Walbek mentioned are evident hear, so a juvy RN Duck molting into first winter plumage fits well with your great photo. Those structural features would include: Flat and upward sloped top of head, with peak at rear of crown Flat, straight back of head. Tufted would have rounded head. Bill of RN Duck is slightly longer than scaup or Tufted Duck, although that is not diagnostic. What other structural features can we see? One interesting thing about this photo is that the eye is bright yellow. Glenn's photos of juvy RN Duck showed dull yellow eye! Is the same individual or is eye color affected by lighting?
Finally in the European guide, "Bird Identification" by Harris, Tucker and Vinicombe, on page 45, there is a drawing of a juvy/first winter RN Duck with the caption, "Eye dull, WISPY CREST DUE TO MOULT". Also a hybrid (adult) drawing is on the same page.
What else can we learn that will help us separate juveniles of these very similar species - RNDU and *TUDU*! There was certainly a big TOO DOO at Marston yesterday.
Joe Roller, Denver Comments welcome.
On Sun, Oct 28, 2018 at 11:13 AM <myrongerhard...> wrote: