Juvenile Caspian Gull Completes the Full Set or Does It?

I was back at Shawell today searching through hundreds of second year LBB Gulls in the hope of re-finding the Baltic Gull. I didn't manage that but I did see a lot of worn and faded primaries.

So what set have I completed? Juvenile gulls of course. Gulls don't keep their juvenile plumage for long, so it's good to get them early.

By 'A Full Set' I mean juvenile Lesser Black-backed , Herring, Yellow-legged and Caspian Gulls.

Juvenile Yellow-legged Gull, Shawell A5 Lagoons

The first juvenile Yellow-legged Gull arrived on July 4th and up to five have been present since although only one was around today. The first juvenile LBB Gulls turned up on the 8th and at least 20 were there today. Next came Herring Gull with one on the 15th and two today, So that only leaves juvenile Caspian Gull.

I wasn't really expecting a juvenile Casp, because they usually turn up in the UK in August. They are early breeders so one could arrive. Its not far to Poland or east Germany as the gull flies after all.

I spotted a gull this afternoon on the lagoons and said to Steve Nichols that it looked like a juvenile Caspian Gull. 

Juvenile Caspian Gull?, Shawell A5 Lagoons, 18/07/15 - Video Below

It was quite a small one so presumably a female. I was pleased to see that it revealed long gangly legs when it stood up in the shallow water. It is typically high breasted, elegant and has the snouty look about it. The dark centred greater coverts are spot on as well. We watched it fly off and I was relieved to see it had a blackish tail bar and clean white upper tail coverts, plus whitish underwings. I haven't heard of another juvenile Caspian Gull in the country yet, so this maybe the first this year.

That said, a question has been raised over its identification based on the contrast between the upper and lower parts. I have been asked to check as it is difficult to rule out a juvenile YLG.  At present the opinion has swung back around in favour of my original identification. Clearly this is a difficult one, so any opinions will be gratefully received. Gulls can be very complicated and thought provoking and at present my head is beginning to hurt a little!

The consensus of opinion seems to favour some sort of hybrid, but this one has proved to be a bit tricky.

It was quite distant, so once again it was better to video it.

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