Thayer’s Gull thing…

Thayer’s Gull?

On the 11th of February Rodmund found a putative adult Thayer’s Gull in Vestmanna. On the following day we went to look for it and after six hours of searching we relocated the bird. It showed very well along with 60 Iceland Gulls, 3 Kumlien’s Gulls and a few Glaucous Gulls.

Thayer’s Gull?

I’m not an expert on Thayer’s vs Kumlien’s Gull and they’ve been lumped as variations of Iceland Gull. The bird is non the less very close to Thayer’s Gull when it comes to wing pattern. On the gull research org home page similar looking 4th winter Thayer’s Gulls can be seen:

http://gull-research.org/thayers/thayers5cy/5cyfeb028.html

Without making any bold claims this bird surely lies very much in the Thayer’s end of thing considering the Thayer’s – Kumlien’s – Iceland Gull continuum.

Iris

 

Wing pattern

 

Thayer’s Gull?

And nailed or not… seeing this bird was surely magnificent. A video of the bird can be seen here:

Other birds around during recent days include hundreds of Iceland Gulls, a Great Tit in Klaksvík, Steller’s Eider in Sumba (long-staying female seen by Rodmund today), male Merlin and a Common Merganser in Hvannasund.

Common Merganser

 

Merlin

Silas Olofson

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2 comments on “Thayer’s Gull thing…

  1. Rodmund á Kelduni says:

    Hi Silas.

    As you know, the AOS (North American Classification commitee) don´t have Thayer´s gull on it´s list as a full species as it is lumped with Iceland gull, therefore it make no sence to talk about Thayer´s nor Kumliens gulls, as they now are a variation of Icland gull.

    So when you write, Thayer´s thing as a head line or Kumlien´s gull in the video it make no sence, just Iceland gull. (morph ?)

    It will be interessting to follow varios European rarety commitee´s decissions hereafter, they did not follow the BOURC but listed Thayer´s gull as a full species, what now ?

  2. Cornelius says:

    Hello Silas and Rodmund,

    Interesting bird for sure. But when referring to “Thayer’s Gull” (or “Kumlien’s Gull”), for historic and taxonomic reasons, I would consider it best to consider these denominations as if they were signifying certain populations with a certain variation – not morphs. On the other hand in field ornithology it is legitimate and best to talk about an “Iceland Gull of the Thayer’s-type” or an “Iceland Gull of the Kumlien’s-type” or of the nominate-type or of integrates between those types. To use the word “hybrid” does not make sense in field ornithology when referring to the three Iceland-Gull-taxa, because we never know if each parent was a descrete member of a descrete population.

    The main problem is, for taxonomy and field ornithology alike, that these populations are associated with certain features and that there is a lot of instability in most large gull populations since they are not reproductively isolated even from other so-called species.

    In case of your bird I would talk about an integrate of Kumlien’s-type and Thayer’s type. I assume that these birds might not have occured as breeders at Baffin island in the 20th century but only further west. Maybe more typical of eastern Thayer’s or it is an x-generation-“hybrid” (which is probably true for most gulls – but you know what I mean: a “rather recent hybrid” with the assumption that somehow descrete populations do still exist), which does not even exclude the possibility of Herring-Gull influence. But this is speculation and I would not place a bet on that birds like these do not occur on Baffin nowadays as part of modern Kumlien’s Gulls (nor can I fully exclude that the variation of Kumlien’s in the 20th did include this type).

    There is however one feature that possibly hints more towards a bright Thayer’s Gull (= a very western bird) and these are the exceptionally wide white fringes in the secondaries and tertials, a feature typical of all pacific taxa of large gulls and a feature that in my opinion is dominant and visible across species (probably because of gene-drift = hybridisation). But I haven’t studied whether there actually is a gap in this feature from “Thayer’s Gull” towards nominate or Kumlien’s. That might be something to look into.

    Kind regards, Cornelius

    Please keep posting those beautifull impressions of the landscape around your observations. I miss the Faroes.

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