|Pictures courtesy and copyright of JFT|
Not long after I published this post I had a text message off Ian Lewington saying this was an interesting looking tern, possibly a first summer (2CY) Arctic Tern that had failed to undergo it's first primary moult. Unfortunately, even though John saw the bird in the morning and at lunch time, he had only seen it sat on this buoy. so he did not see the open wing or have any photos of the open wing.
John had sent me a photo of the bird and we discussed it briefly. Even though we both said the bird looked structurally like an Arctic Tern we concluded it must be an Common Tern because it still had dark primaries (for reference see this post of a bird we had earlier this year).
A couple of emails with Ian later and he was fairly happy to conclude that this was an Arctic Tern, based on it's structural characteristics. However, after a bit of research it was more interesting than just a second calendar year bird. This is what Ian wrote:
'I think we can safely say this is an Arctic (short legs, short bill, cap shape, general shape etc). It was it's state of moult that puzzled me. I've since learnt that 3rd cal year birds do not have a complete pre-breeding moult in early spring unlike 1st summers and adults. In their 2nd summer they have a body moult but do not replace their primaries (except sometimes p1 or p2). There is a hint of a grey p2 tip on the photo. The bill is also more colourful than a 1st summer.
So a bird about 27 months old! Very educational and I don't recall this plumage/age class in the county before.'
So that's another Arctic Tern I've missed this year!