Early morning start at the Bill produced plenty of Yellow Wags flying about also a few Tree Pipits and a nice adult Hobby chasing some small passerine around. Down to the Bill Common where there were a few loafing Gulls, one of which immediately caught my eye as being very dark and very long!
Here are some shots, the first one is a pretty mad posture.
Well, what do you think so far!? I think it looks quite good for a fuscus, structrually its not bad, it is probably dark enough, it is certainly long enough! The bill is quite slender and the eye looks quite small, but the legs do look a bit long.
The pic above shows that it has got new P1 and P2 which is also consistent with fuscus (and intermedius) but the mirror looks quite big. Answers on a postcard.
Sent these pics and a couple of others to Killian for some expert opinion.
He commented as follows (and kindly added some graphics to the flight shot)
"What an amazing looking bird! I can certainly see why you may have considered this bird possibly a fuscus on the length of the wings alone!
I think Lars Jonsson's 1998 paper established pretty conclusively that the size of the white mirror on p10 does not constitute a really reliable means of differentiating between fuscus- and intermedius-types. Also, unfortunately, I think it has been demonstrated that some intermedius are remarkably long-winged.
From the larger shot of the bird flying away it appears that the bird is moulting more like an intermedius than a fuscus (see attached below). In particular, the fact that it has dropped p3 would count against it being a fuscus, as would, perhaps, the fact that it is in such 'active' wing moult while (presumably) on migration?"
Click to enlarge