caspian gull pitfalls

 so the long staying caspian gull at redcar tarn is labelled as a common gull on birdguides!!! they need to sort out the algorithums 

going through my photos this caught my eye 

clean headed,nice shawl, beady eye, looks like a classic 1st winter caspian gull 

but more photos 

credit to steve clifton  for commenting 

'Another interesting individual, and I have to admit that on first impression I thought it was (almost) a 1cy Caspian Gull.

However, there are quite a few things wrong. The tertials have broad fringes with internal markings, and the wing coverts look to be largely second generation. Also, the underwing isn't obviously pale/white enough for a Caspian Gull (either 1st or 2nd yr) and from what I can see the primaries are round-tipped. P10 is also shorter than P9, which also indicates a 2cy, as you'd expect any 1cy UK gull to have fully grown it's primaries this late in the autumn (2cy birds will still be just about completing moult of their flight feathers around now, so outermost will still be growing).

I think it's a 2cy 'Herring Gull', but due to that very snouty look, quite probably one with some Caspian genes in the mix-in fact I'm almost certain of it. Note that the iris is quite pale (for a 1cy, but not for a 2cy) and P10 lacks the sub-terminal mirror that you'd expect to see on a normal 2cy Caspian.'

birdforum is a great resource to have at your finger tips 

thanks steve