Here are some clarifications and cautions from someone who has far more experience with Yellow-legged Gulls than I ever will.  Also note that Marcia Balestri is posting the package to IDFrontiers.  That should produce a flurry of responses.  You can find IDFrontiers at <www.birdingonthe.net>, click on Regional/Specialty.

Paul O'Brien
Rockville, Mont. Co., MD
 
Begin forwarded message:

From:   pobrien776 <>
Subject:    Re: [MDOSPREY] Adult Yellow-legged Gull
Date:   November 20, 2009 12:48:04 PM EST
To: "Andy Wilson" <>
Andy,
I share your cautions.  The mirrors threw me off until I looked at Howell and Dunn, particularly figure 26.1, which shows a good sized mirror as well as extensive fine streaking.  I, too, thought of incomplete molt when I saw the primary extension.  I have no solution for that question, which is one of the reason's I wanted to get more birders, particularly the ones with the gigantic cameras, looking for and documenting this bird.  Flight photos would help on the primary molt question, and on subspecies too.  The size should approach Herring Gull.  I should never have thrown Ring-billed Gull into the equation.  We learn by errors.

Paul O'Brien
Rockville, Mont. Co., MD

On Nov 20, 2009, at 7:55:51 AM, "Andy Wilson" <> wrote:

From:   "Andy Wilson" <>
Subject:    Re: [MDOSPREY] Adult Yellow-legged Gull
Date:   November 20, 2009 7:55:51 AM EST
To: 
Thanks for posting the photo link Paul - an interesting bird. While it has lots
of good value for a Yellow-legged Gull, there are a few things that allow some
room for uncertainty in my opinion. I'd like to hear the opinion of others with
experience of this species.

My main concern is the size of the white mirrors on the primaries - they should
be small on Yellow-legged, they look large on this bird, certainly larger than
is typical for Yellow-legged. Some of that could be an artifact of the
photographs - difficult to say. Also, Yellow-legged has longer primaries than
Herring - this bird has a very short primary projection. Of course that could
be moult, but note that Yellow-legged Gull (at least the western European race)
moults earlier than Herring Gull, and I would have thought would be through
moult by now. I'm not too sure of the moult timing of other races though - so
that's worth investigating. 

Also, the streaking on the head is definitely towards the extensive extreme for
Yellow-legged Gull. In photo 6 - the streaking looks extensive but very fine.
Size is difficult to judge but Yellow-legged is pretty close to average Herring
Gull size, there is extensive overlap among the various races of both. It's
usually noticeably larger than Lesser-Black-backed (when side by side), a
Yellow-legged between Ring-billed and Herring size would be odd.

I don't think any one thing rules out Yellow-legged but it's certainly doesn't
look like a classic bird of the races I'm used to seeing in Europe and North
Africa. This species complex is, well, complex though!

A good find whatever the outcome.

Andy Wilson,
Frederick


<A name=1258667211>Subject: Adult Yellow-legged Gull</A>
From: pobrien776 <pobrien776 AT AOL.COM>
Date: Thu, 19 Nov 2009 16:46:34 -0500
For those of you who may be in the vicinity of Blackwater Refuge this weekend, 
be on the lookout for this gull. �It was seen last Friday (the 13th!) by
Marcia 
Balestri, but not relocated over the weekend. �It was with a flock of mostly 
Laughing and Ring-billed Gulls foraging in the fields along Egypt Road north of 
Key Wallace. �For all we know it could be in North Carolina by now, but it is 
certainly worth looking for. �It will be slightly darker in the mantle and 
midway in size between Herring and Ring-billed Gulls, but with yellow legs. 
�Many of you probably missed the 1993 bird at the Oaks Landfill in 
Laytonsville, Montgomery Co. �It shuttled between the landfill and Georgetown 
Reservoir. �It was a return of the first documented North American record
which 
had been found by Dave Czaplak at Georgetown in the winter of 1990-1991, as I 
recall. 


Photos can be seen at:

http://picasaweb.google.com/BobsShots/Gulls

Good luck!

Paul O'Brien
Rockville, Mont. Co., MD
Eared Grebe - Piscataway Park PG Cty</a> [Joe Hanfman ] 
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