RE: Teachable moment. Please post your photos for study.

[Glenn Walbek]

https://ebird.org/view/checklist/S49494502

 

Sent from Mail for Windows 10

 

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From: Joe Roller <jrol...@gmail.com>
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

[myrong...@gmail.com]

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

[Joe Roller]

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.

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[Peter Burke]

COBirders,

A friend of mine posted this photo of a female Tufted Duck today so I thought I'd share it with the group. It's a bit of a closeup, but interesting to look at...

Good birding,

Peter

Peter Burke

5590 Spine Rd. #204 Boulder, CO 80301

(973) 214-0140

Flickr  LinkedIn

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