Herring Gull (larus argentatus/argenteus) - Rainton Meadows DWT - February 2012

The photo of the below bird really did make it stand out from the crowd when I observed it in the field around about a week ago, what struck me immediately when I picked the bird up was the very bulky size and almost raised forehead. So is it argenteus or argentatus?

(Herring Gull - © John Bridges)

Looking at this bird standing on the ice its clearly fairly large and bulky, a very deep chested appearance, a lot of white in still visible in the primaries even at rest, the mantle is fairly dark (compare to larus argenteus to the right), I therefore conclude this bird to be an argentatus. Overall the bulk and jizz of the bird are reminiscent to me of a mini Glaucous Gull. What does strike me as a bit odd is the inner greater coverts look like they have a dark shade to them, I have images of the same bird as I was there the time the photograph was taken and this dark shade is still present. Perhaps the bird has been a little oiled in that section of the wing? 

I think Herring Gull is a very overlooked bird and I believe are deeply interesting birds and great to study the variation in the field when not many other 'interesting' Gulls are around.