LBBG?

[WolfgangSchweighofer]

Hi,

today 12 -15 large gulls at Wörth/Austria. Most of them cachinnans, one of them PALC from Poland. Among them also a very dark indiviual. From distance (nearly 100m) I had no doubt that it was an abnormal coloured CG. Especially white head and breast, contrasting well to the boa of dark neck streaking, and the slender structure looked well for this taxon.
Pictures revealed, that it was a LBBG, very uncommon and unexpected at this time of year here in Austria.

But what subspecies can it be? I have really no experience with 2cy at this time of year, but none of the few available pictures in the web fit to any subspecies...
Excuse the quality of pic´s, very high distance...

[Theo Muusse]

It shows a high amount of 2nd gen coverts!
Also upper tertials are 2nd generation.
This should leave fuscus and intermedius out and narrow the choice to graellsii or heuglini...
I hesitated for a moment if it is a 3cy bird, but its a 2cy alright.
Theo

[WolfgangSchweighofer]

Interesting! With this choice I would take heuglini

I haven´t expected that graellsii has such a white head at this time (early January). And I had ruled out graellsii here in Austria. But if the palest birds from northern Norway are graellsii indeed, then it is possible.
Heuglini would be nice, but will be impossible here in January...

A poor flightshot (focus was on PALC, unfortunately covered by a COGU).