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Not a Thayer's....right? ad. winter large white-headed gull | Choshi harbour, Japan | march 5 2020 (1 Viewer)


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I have been trying to determine what this is myself for quite some time now. But I fail to see what others seem to clearly see: something is or is not a Thayers Gull.
It is a bit like a firstgrade student trying to solve a 5th grade puzzle with only the firstgrade tools and knowledge.

So here goes:
it concerns this bird: Thayer's Gull (Subspecies Larus glaucoides thayeri)
All photo's with this bird in it are shown here: flickr album of this bird
my reference bird is this one from Carlos Ibañez: photo Thayer's Gull | Choshi | 1 March 2020
That bird looks friendlier than mine but...
I simply stopped seeing which are the features.... hook on p6? grey underside to primaries, dark iris, reddish purple orbital ring.... long primary projection... I am lost.


Since I first saw the photo-series (about a year after) I have spent a few hours trying to figure out what makes a Thayer's.

What would you make of it? For the record: the admins at observado.org have not judged this record yet, so it might be unsolvable.

hope to hear from you

Hi Gerben,

Completely out of my competence, but maybe these pages from the blog of Neil D from Kyoto who is has been a keen guller in Japan for decades will be of help. He is a member here, but only looks in rarely. His Thayer posts are from Mie Prefecture.

I noticed when at Choshi that, on Vega Gulls with Thayer's-like wingtip patterns, the black areas on the primaries were black below as well as above. On Thayer's, these areas were all 'greyed out', producing a ghostly white underwing. I see this on your third image above (compare the underside of the primaries on the far wing with those of the Vega in the background). The solid-looking head markings look right to me for Thayer's, and to me this bird also looks pale enough.



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@MacNara thanks I am closely following his blog (on and off) I have read most of its pages...but chaotic as I am I think I have not read that section recently.... good tip.
Of course the main source is always gull-research.org but without a firm knowledge base that site can also be a well to drown in : )

@SteveMM thanks for noticing the same things I did. It is not that far fetched then ; ) It remains strange then that so few people seem to dare to comment. I should ask Carlos about his record and mine.
Nice comparison! Thanks and good to see the all pale underside of primaries. Unfortunately, I do not have a photo of it flying, although I should go over the timeslot forensically to maybe find at least a hint of a flying underwing.

The main thing seems to be that I doń't see a relatively gentle Iceland Gull in this bird.

I hope someone else drops by too!

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@SteveMM Yes that was the checklist I found when I first went for a search of the ID of this bird back in spring last year (a year after)
I think what most strikes me is, is that the gentle mental image I have of Iceland Gull is totally absent here...as it is in Carlos Ibañez' bird.
I have been looking for proof that these two records concern the same bird, but he and I seem to have photographed the other side of the head.

@jmorlan your bird seems to be more what I expected of a blackish winged Iceland Gull.

More and more I seem to see that the bill structure of all these birds is more or less the same.

I am starting to actually be more convinced..hooray for that.....

btw I should have change its age to 4CY I think (subadult)

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