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Wednesday, 22 December 2010

Mystery gull




Found this bird today. The rectrices and uppertail covert pattern look suggestive of American Herring Gull but the bird lacks dark bases to the greater coverts, has marbled tertials and the undertail coverts are sparsely marked.
I am leaning towards perhaps a AMHGxGLAUC hybrid (Nelson's Gull) but also perhaps something from the problematic Iceland populations. It is possible that it is a very unusual argentatus and perhaps also a EUHGxGLAUC hybrid (Viking Gull)- although the all dark rectrices and heavily barred uppertail coverts just look too extreme.
and here:

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2 comments:

  1. john22 December 2010 at 23:10

    I tried to figure out the gull using my North American Field Guides, (The Sibley Guide to Birds being the most useful). I had it narrowed down to either a first winter American Herring Gull or first winter Slaty-backed Gull. I guess you guys decided it was the first.

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  2. Peter Alfrey22 December 2010 at 23:33

    Hi John,
    It is not quite right for American Herring Gull or Slaty-backed but certainly resembles one in several ways.
    It could be a hybrid from the Americas (which may involve AMHG)but please send us a straight forward American Herring Gull!
    Cheers John
    peter

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