During a short visit to Stockholm, Sweden I was able to spend a few moments observing the local Scandinavian Herring Gulls Larus argentatus argentatus.
I mainly focussed on the adults and was pleasantly surprised by the many individuals showing reduced black in the outer primaries, a Thayeri-patten on P10 and/or P9, and long tongues on the underside of P10. One individual had yellow legs while another showed a grey mirror on the underside of P10. All good stuff and much different than the primary patterns of European Herring Gulls Larus argentatus argenteus that I am used to seeing in the Netherlands.
We do get to see Scandinavian Herring Gulls in the Netherlands though (mostly during the winter months) so I am familiar with their characteristics, but it was nice to see them where they should be seen: in Scandinavia.
All photos were taken at Gamla Stan, Stockholm, Sweden 21 February 2015.
Bird #1
Individual with dark mantle, yellow-tinged legs and Thayeri-pattern on P10 and P9. Very much the way I like to see them.
Bird #2
Individual with full white tip on P10, reduced black on P9, black on the outer web of P5 and a small black spot on the outer web of P4 (right wing only).
On the underside of the wing a grey mirror (sometimes referred to as a pseudo-mirror) on P10 can be seen. (For more details about this phenomenon, see Adult American Herring Gulls, seen from a Dutch perspective and scroll down to Supporting features.)
Various birds
A compilation of primary patterns of the underwing, showing the difference in tongue pattern on P10 and Thayeri patterns on P10 or P9.
Gulls to the Horizon 