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:

> [image: IMG_6024xx copy.JPG]
> Thanks to Bil Ford, this morning we were able to get better photos of this
> bird. I have posted photos at this ebird post:
> https://ebird.org/view/checklist/S49516513 for Marston Reservoir. Note
> that the bird did not dive while we watched (so I assume the head is dry).
> Also it was well away from any other bird - at least 1/4 mile - and over by
> the isthmus, very near the shore. I have more photos in case there is some
> body part you want to see. Any chance this is a hybrid?
> Myron Gerhard
> Littleton, CO
>
> On Sunday, October 28, 2018 at 8:28:20 AM UTC-6, Glenn Walbek wrote:
>>
>> https://ebird.org/view/checklist/S49494502
>>
>>
>>
>> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
>> Windows 10
>>
>>
>> ------------------------------
>> *From:* Joe Roller <jrol......>
>> *Sent:* Saturday, October 27, 2018 9:17:22 PM
>> *To:* Glenn Walbek
>> *Cc:* John Drummond; Joey Kellner
>> *Subject:* Teachable moment. Please post your photos for study.
>>
>> I saw your revised checklist.
>> Would help me learn the structural points, etc if you re-attached the
>> close photos you took of the RN Duck, as were on your earlier list.
>> Thanks, Joe
>>
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