Adult Caspian with atypical primary pattern

[adriaens]

Surely Ruud is refering to the combination of p5 and the perfect argenteus-p10, leaving Herring is a serious option on this one.
Actually, p5-p10 is very good for herring.

I do not think P10 looks 'perfect' for argenteus; on the upperside of this bird, this primary has quite an extensive grey base - a bit more extensive than in the average argenteus (see e.g. https://picasaweb.google.com/Zorkyyy/Ad ... lourRinged#).
Also, the upperparts look a bit darker grey.
I guess it could be a Finnish Herring Gull or so, but the dark iris and parallel-sided bill could well indicate some influence of Caspian Gull.

[Neil Morris]

Here's the only other pic of this bird in flight.

[Hans Larsson]

I´d put my money on Caspian Gull. Structure both in flight and on the perched bird looks just fine and as Lou states, this primary pattern seems to be regular, although rare. I don´t get any real HEGU impression from this bird. It´s always good to be cautious outside the core range, though, so in a British context, one would probably prefer only the most "classic" birds to be safely labelled as Caspians.

/Hans

[JanJ]

As Hans I´m also prepered to put my money on Caspian, at least on the ground. As it seems, the lack of a complete dark mark on p5 is not unique in Caspian
(% I´m not aware of) - this one having a tiny dark mark on the outer web of p5. It´s very difficult to obtain a reliable view of the pattern of the outer primaries (p10 + 9 & 8) both on upper and underwing due to blur. Do we really see the exact pattern of p10?
In this one (Jörgen Bernsmo) the difference between the upper and lower wing is quite obvious and highlights the difficulties to judge from certain images.
As soon as we see the lower wing we might become more comfortable calling it Caspian, if now we should judge from a wingtip pattern point of view.

http://www.pbase.com/slisch/image/131782181

"Lots of dark"

http://www.pbase.com/slisch/image/108646295

Another good view of primaries:

http://lou.bertalan.de/gulls/pic/vh/up_0778.jpg

The subject gull is also featured here:

http://www.birdersplayground.co.uk/Casp ... s%201.html

JanJ