Hey Birthe,

if this was a Caspian Gull it would be the first adult lacking a p9 mirror. :) Because of this and the serrated tongue edge of the outer primary (p10) I'd suggest this is a hybrid cachinnans x argentatus (the so called 'cactus').

all the best,

Lou Bertalan

Hi Lou

This is a 5cy bird with black on primary coverts - see photos here and here. Couldn't that be the reason to the lack of p9 mirror? 

Do you have many examples of cactus showing no p9 mirror? 

I mean most (>98% ?) of nominate Herring Gulls also show p9 mirror, so why this should be a feature of cactus, I can't really comprehend.

Enlighten me please?

Best wishes, Rune

Hej Rune.

Tak for dit svar til Lou Bertalan. Jeg vil ikke kunne indgå med noget konstrutivt til dialogen, dertil er min viden om kaspisk måge ikke stor nok. Jeg er i dialog med min fætter Torben Sørensen om måger og stadig i en læringsproces.

Mh Birthe