Herring gulls in Oslo

I was in Oslo earlier this week. Spent most of the daylight hours on Wednesday (11th February) around the harbour. I read colour rings on 27 different Herring Gulls Larus argentatus (N=gråmåke). All of these had been ringed around the Oslofjord, and most of them from within the boundaries of Oslo itself. I took lots of photos in the bay beside the Oslo Opera (Bjørvika). As the birds have been aged when caught for ringing I was able to look more closely at ageing of known individual gulls, which was a useful identification exercise. Here are some of the photos I took, sorted according to age of birds:

J8457, 2nd calendar year

 

J783A, 2nd calendar year

 

J8367, 2nd calendar year

 

J7315, 3rd calendar year

 

J4421, 4th calendar year

 

J7594, at least 5th calendar year

 

J2905, at least 8th calendar year