Sunday, 17 July 2011

Seaton Area

Please forgive this lengthy post - I thought this might be of interest to the millions of other Devon birders who like gulls.

The gathering of large gulls on the Tesco site didn't produce any Yellow-legged Gulls this evening, but the White One was present again. I've always thought the balance of probabilities made it a Herring Gull rather than a Lesser Black-backed Gull (despite its relatively small size) and some detective work today seems to confirm that notion. Firstly, its age. This is what it looked like in Feb 2010...



Assuming the current beast is the same bird (and it seems rather likely!) this is what it looks like now...

Note the yellow bill, and a nice blotch of red on the gonys. Also a dark sub-terminal mark on upper mandible.

According to Malling Olsen and Larsson's gull bible, red on the gonys generally appears in the spring of the 4th calendar year. If it is indeed a Herring Gull, its bill in the two photos comfortably matches that of a 2nd-winter in Feb 2010 (its 3rd calendar year) and a 3rd-summer in July 2011 (its 4th calendar year).

And there's more - an open wing photo from today...

Note the nice new primaries from P1 to P6, whilst the outer feathers (P7-10) are all still unmoulted, and worn to the shafts. Again according to Malling Olsen and Larsson, LBB Gull would not be so far advanced at this time of year (usually not completing the moult of P3-6 before late August to early September) while the above state of affairs is perfect for a sub-adult Herring Gull.

Job done - the White One is a 4CY Herring Gull. Quite probably.

Thrilling stuff. And on Black Hole Marsh were 5 Dunlin, up from 2 yesterday. Here are 4 of them...