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

[HouseCrow]

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

cheers,
Gerben

 

[Butty]

Japan?

 

[HouseCrow]

Yes, sorry added country in the title now..
Thanks
Cheers

 

[MacNara]

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.

BIRDING - Kyoto, Kansai and Japan

A personal view of birds and birding in the region

birdingkyoto.blogspot.com

 

[SteveMM]

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.

Steve

 

[HouseCrow]

@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!

cheers,
Gerben

 

[SteveMM]

The bird in your series looks remarkably similar to the first (flying) Thayer's Gull in this checklist (https://ebird.org/checklist/S65513396): a checklist you might be familiar with!

Steve

 

[jmorlan]

Here's what we identified as a Thayer's (Iceland) in Choshi:

ML143227411 - Iceland Gull (Thayer's) - Macaulay Library

Macaulay Library ML143227411; © Joseph Morlan; Choshi, Chiba, Japan

macaulaylibrary.org

 

[HouseCrow]

@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)

cheers,
Gerben

 

[HouseCrow]

quick update: The gull gods and their human representatives have checked my record at observation.org and deemed the ID correct... It was a Thayer's Gull after all.

check: Thayer's Gull - Larus glaucoides thayeri 2020-03-05 | Japan

I am not sure who checked my record, but I think it is safe to say they know what they are talking about.

thanks for the help with this one

cheers
G erben