So, I'm no expert on Yellow-legged Gull, but I have studied the taxon from here 
in North America from time to time.  I've often seen birds that I think could 
be one form or another of YLGU.

Eliminating hybrid Lesser x Herring is going to be very hard.  I think that has 
to be the default explanation here, in spite of the very yellow legs.  Do you 
have closeups of the orbital ring?

As for YLGU, your bird seems to have too much head streaking for any of the 
forms in late February, even lusitanius. I also think YLGU should have a dark 
mark on P5.  But by all means, post the photos to the Western Palearctic Gull 
forum on facebook.

Some photos I took in Spain in summer 2018:    
http://home.bway.net/lewis/birds/ylguns.html

Shots of a similar bird at Hatteras on Jan 25:  
https://www.flickr.com/photos/rfermat/albums/72177720296308518

Bob Lewis
Durham NC




 On Thursday, February 24, 2022, 08:48:01 AM EST, Shaibal Mitra 
<shaibal.mi...@csi.cuny.edu> wrote: 



Dear ID Frontiers NYSBirds,

I would appreciate feedback regarding an adult yellow-legged Larus found 22 Feb 
at Old Field Point, on the north shore of central Long Island, New York.

Broadly speaking, it is a Herring Gull type, but there are reasons to doubt 
each of the usual (and less usual) interpretations of Herring-like gulls with 
yellow legs in this region at this time of year.

Most often, such birds prove to be otherwise typical smithsonianus Herring 
Herring Gulls, which regularly show some degree of yellow color in the legs and 
feet in late winter and early spring (as do small numbers of local Great 
Black-backed Gulls). Another frequent interpretation is Herring Gull x Lesser 
Black-backed Gull hybrid, which the original finder, Patrice Domeischel, 
considered in the present case because of the bird's slightly darker than 
smithsonianus mantle. A third possibility, always present in the minds of New 
York gull aficionados, is Yellow-legged Gull, which was considered by Patrice, 
and also by Peter Osswald, who independently found the bird on 23 Feb. 

Patricia Lindsay and I studied the bird yesterday afternoon (23 Feb), and I 
have reservations about all three of these hypotheses, which are explained in 
my eBird report (link below). Briefly, Yellow-legged Gull is counter-indicated 
by this bird's heavier than expected head and nape streaking; it's notably 
large (larger than typical smithsonianus) apical spots on the primaries; and 
other details of the wingtip pattern (more white, less black than typical for 
smithsonianus, let along Yellow-legged Gull). The latter two points regarding 
the primaries also point away from Lesser Black-backed Gull ancestry. Finally, 
American Herring Gull is problematic by virtue of the subtly (but clearly) 
darker than typical mantle tone; the completely clear yellow tones of the the 
legs and feet; and details of the wingtip pattern. I could not see the orbital 
ring color. Photos by Patrice and Barbara Lagois seem to show it is red, but 
are not decisive on this point, in my opinion.

I wonder if this bird might represent a yellow-legged example of northern 
European L. a. argentatus, which I do not know well in life, but which is 
described as having a slightly darker mantle tone than smithsonianus, a wingtip 
pattern very similar to the present bird, and a relatively high incidence of 
yellow leg color.

My preliminary analysis (with photos by Barbara Lagois) and two of Patrice's 
checklists, also with excellent photos can be found here:

https://ebird.org/checklist/S103599677
https://ebird.org/atlasny/checklist/S103599196
https://ebird.org/atlasny/checklist/S103596988

Shai Mitra
Bay Shore, New York
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