Siguiendo con el tema de la báltica anillada con rasgos extraños, voy a pegar aquí las respuestas de Ruud Altenburg y Hannu Koskinen, que tienen mucha más experiencia en temás de fuscus nominales.
"very nice to see this! Those N Norwegian birds are difficult to identify of course as no one really knows what's happening there at the moment (pure or mixed pairs?). A bird that's just started a complete moult is unlikely to be anything but a fuscus, you'd say. All dark bill and so much head streaking is atypical though. Probably a bird of mixed origin? Also see, eg http://www.gull-research.org/heuglini-id/fuscus1.html and Hannu Koskinen has more N Norwegian birds on his site" (Ruud Altenburg
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"This bird is ringed in Horsvær at Helgeland, were we have more or less stable colonies with fuscus type birds. We see a few paler birds here, but so few that we classify all chicks as fuscus. Normally we only classify adults, not chicks, when ringed in mixed colonies, but in this area we only have one single bird in 400 pairs that are more or less pale." (Morten Helberg
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About J942: I personally lack totally field experience of large Gulls at their wintering grounds (but of course have seen a lot material in web and photos etc.). However, i use to see lots of 1st-summer fuscus in Finland annually. Some of them are really heavily streaked, particularly on lower neck (and tend have rather fine streaks on head, not so dirty and blotchy) . So i wonder why not at least some part of the 3rd winters too? Here some examples photographed in Israel, some of them after moult during spring migration already. Some Norwegians included also: http://www.jbo.org.il/RECOVERIES/recoveries.htm J942 is after all very dark; in these photos no shade of any grey visible. Without any other speculation I consider it to be at least very close to nominate fuscus (Hannu Koskinen)
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