Thayer’s Gull in Iceland?

Challenging 2nd winter plumage

Martin Garner and David Walker

First off checkout this amazing photo of the awesome gull swarm at Olafsvik, Iceland last year. From Dungeness Bird Obs warden Dave Walker- man you wanna go there!

Martin Casemore Plodding Birder and David clocked the darker bird looking a candidate 2nd winter’s Thayer’s a few days ago at Grundarfjordur, Iceland. It’s a bit of a scary bird, so a few photos and some comment. Lot more pictures of the bird on the Dungeness Bird Obs website.

gull flock (1 of 1)

 

 Gull sp , Grundarfjordur, Iceland, March, 2015

t12 (1 of 1)t125 (1 of 1)t123 (1 of 1)t17 (1 of 1)

 From MG:

“From the first photos it is pretty Thayer’s like. Indeed I suppose it may well be the progeny of 2 adult Thayer’s. However for ID purposes of vagrants I would not peg it as identifiable/ acceptable if it was say in the UK. There are a number of features that put it into the uncertain/ what is going on? box. On the broad front I wonder if there is some pioneer zone where there is some gene mixing- say NW Greenland and these scary ones show up from.

Specifically- and your photos show this much better- it is very mealy dark/light patterning in greater coverts- most often thayeri is quiet plain, the outer primaries have less dark than ideal- best if it crosses to the inner web- and the pattern starts going weak from p6, also not so good. There is a pale spot even if not a proper mirror on p10 and the little subterminal string of pale spots on p8 ish and inwards is definitely odd and maybe better for kumlieni I think.

So that combined set of slight oddments are a least at ‘edge’ of acceptable 2nd winter Thayer’s would make me say it’s best left as Thayer’s -like but uncertain ID. It’s not dissimilar to some we showcased here  and those features are hashed out further here. I have seen quite a few 2nd winter Thayer’s and most look more straightforward- which is of course you want when claiming vagrants! Always learning…”

2 thoughts on “Thayer’s Gull in Iceland?

  1. Suzanne Sullivan

    Hmmm Very interesting gull. I think the miss mash plumage indicates a hybrid of some sort. Wonder if this is what a true HERG X ICGU really could looks like? Or maybe a LBBG and ICGU? For some reason this bird recalls LBBG to me and the outer primaries seem to be very Kumliens. Seems we don’t consider that combo at all. Maybe we should. Considering here in North America we do not know where the LBBG’s are nesting and their population seems to be increasing every year and the tendencies of gulls to mix and mingle with each other seems like a scenario worth throwing into the mix. We already do know they will hybridize with the Smith HERG. I have had several gulls I suspect it could be the case.

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  2. Pingback: Juvenile Thayer’s Gull in Iceland | Birding Frontiers

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