Sunday, 22 April 2018

Possible Eastern Common Tern, Pennington Flash

Possible Eastern Common Tern Sterna hirundo longipennis, Pennington Flash 22/04/2018 - Photo © John Tymon
A text from John Tymon alerted me to the presence of a black billed tern at Pennington Flash today. It was a grim morning, pouring with rain from about 9am until noon and very dull. I was hoping for a roseate but John's message didn't suggest that species and when I arrived at the hide the bird was sitting on the spit and just looked like a common tern with a black bill. Except that there were differences. The bill looked a bit too fine, black with perhaps a hint of crimson at the base, the legs were long and black or very dark red and it's underparts were greyish contrasting with very white cheeks. This last feature was even more obvious when it flew, at which time its common tern like primary pattern could be seen. The bird was so dark and it flew in such marsh tern like way that for a moment we even considered and then dismissed whiskered tern.

Click here for a video of the bird in flight

However it was obvious that it wasn't a marsh tern, but what was it?


Possible Eastern Common Tern Sterna hirundo longipennis, Pennington Flash 22/04/2018 - Photo © John Tymon

Our next thought was 1st or 2nd summer common tern, so called 'portlandica'. They're pretty uncommon in the UK, but do occur. However would a bird that wasn't a full adult have a full black cap, and surely the grey underparts with white cheek don't fit either 1st or 2nd summer common? All of the photos I have seen of portlandica terns show a white forehead similar to non-breeding adults, and pure white underparts.

Our final consideration was eastern common tern Sterna hirundo longipennis. This is a race which is yet to be confirmed as occurring in the UK, but there are a number of records under consideration. Notably there was a common tern at Seaforth in about 2008 which was thought to be of this race, whilst there was a similar bird in a tern colony at Abbotsbury in Dorset in 2017.

This bird seems to fit ssp. longipennis, the key features being the slightly shorter, straighter and thinner black bill and very dark legs combined with greyish underparts contrasting with bright white cheeks. Unfortunately the weather was rubbish during it's brief stay at the flash, rubbish for photographs at least. However, shortly after the rain cleared, the bird flew high and away to the north.

Whether or not these photos are good enough to confirm the identification remains to be seen, but it was certainly a very interesting bird. Any comments about this bird gratefully received.

Possible Eastern Common Tern Sterna hirundo longipennis, Pennington Flash 22/04/2018 - Photo © John Tymon
Possible Eastern Common Tern Sterna hirundo longipennis, Pennington Flash 22/04/2018 - Photo © John Tymon

Possible Eastern Common Tern Sterna hirundo longipennis, Pennington Flash 22/04/2018 - Photo © John Tymon

Possible Eastern Common Tern Sterna hirundo longipennis, Pennington Flash 22/04/2018 - Photo © John Tymon

Possible Eastern Common Tern Sterna hirundo longipennis, Pennington Flash 22/04/2018 - Photo © John Tymon

Possible Eastern Common Tern Sterna hirundo longipennis, Pennington Flash 22/04/2018 - Photo © John Tymon

Possible Eastern Common Tern Sterna hirundo longipennis, Pennington Flash 22/04/2018 - Photo © John Tymon

Possible Eastern Common Tern Sterna hirundo longipennis, Pennington Flash 22/04/2018

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