Thursday, 22 December 2016

Caspian Gulls in the Cuckmere (21-22 December)

Thursday 22nd. Finishing work at lunchtime and with the sun shining I decided to revisit the Cuckmere as I was already part way there. Low tide was later and the wind had dropped so I wasn't expecting as many gulls and that proved to be the case. The main flock, of 800+ birds, were in the same field but only half-way across. This time Lesser Black-backs were the predominant species with a rough count of 560 present. Checking through them I picked out a bright-billed adult Caspian Gull (different from yesterday's) and two adult Yellow-legged Gulls. The gulls flew but most immediately returned. Going through them again I saw a smart first-winter although I couldn't find the adult, presumably it hadn't returned. After 10 minutes the first-winter sat down virtually obscured and I continued checking the flock but then couldn't relocate it. All the gulls flew again, some dropping into the next field, some returning and some heading out to sea. The same or another Yellow-legged Gull was seen in the next field but nothing else so I left. Again a Raven flew over calling providing a nice distraction. Images are a mixture of digiscoped and bridge-camera.
adult Caspian Gull in the Cuckmere. This bird had a relatively bright bill, but the sun was shining, and a brownish eye. The brightness of the bill, even accounting for the sun, made it a different bird to yesterday's
showing small white head, snouty appearance, parallel sided bill and long thin legs
showing extensive white on the underside of p10
showing the thin black bar across p5 and very long thin stilt-like  legs
the bill looking longer in this image and the eye smaller
ventral bulge showing well
showing the black subterminal bar on p5 and the grey on the outer primaries cutting into the black
showing the long pale tongue on the underside of p10

gulls in the Cuckmere, the first-winter Caspian is dead centre
a very smart bird, showing all the expected features although I never saw its underwing. Dark bill, a bit foreshortened in this image, very white head and underparts, a few neck streaks forming a shawl, grey mantle with a few dark centres, fairly uniform brown coverts, black tertials with thin thumbnail edges, long black primaries, ventral bulge and thin fleshy legs.

showing the long thin dark bill and a clearer view of its tertials
to me a classic bird
differences from other large gulls might be subtle but combined make an attractive package
fewer gulls in the Cuckmere today
second-winter Lesser Black-backed Gull, not the most familiar of plumages
colour-ringed Lesser Black-backed Gull 6W, also seen here on 17 December. It was ringed as an adult male in Oost-Vlaanderen, Belgium in June 2011, and seen in Zeeland, Holland this June and in northern France (near the Belgian border) in September 
colour-ringed Lesser Black-backed Gull, I wasn't able to read any of it, likewise a red-ringed bird in the flock (with white characters so not North Thames, maybe from Suffolk)
sleeping Yellow-legged Gull
another sleeping Yellow-legged Gull but at least this one was standing up

Wednesday 21st.
A strong wind and an afternoon high tide seemed ideal for large gulls roosting in the Cuckmere and so it proved, but an improving forecast didn't materialise and viewing conditions were poor. The flock was also in the far side of the field opposite Harry's Bush but walking round to the river bank would have meant viewing into the drizzle and would probably have disturbed the flock anyway. As it was they flew four times, most soon returning. I picked out 3 birds that I considered to be Caspian Gulls, a third-winter, fourth-winter and adult, and two adult Yellow-legged Gulls. Poor images follow, much imagination is required ... Two Ravens flew over calling providing a nice distraction.

a lot of large gulls in the Cuckmere, I estimated about 1300 of which 1100 were Great Black-backs
third-winter Caspian Gull (left hand bird), primarily aged by brownish tones on  the coverts. Structurally the bird was all one would expect of this species. Its small white head, small dark eye, long thin bill and anaconda neck are evident in this image. It also had long thin legs, a ventral bulge and an attenuated rear end/long wings
the same bird
the same bird preening far left and the fourth-winter head on far right
the fourth-winter, structurally very similar but with uniform grey upperparts without browner coverts
the same bird, aged as a fourth-winter by the black band near the tip of the bill, otherwise as an adult from what I could see
the same bird in front of a presumed argentatus Herring Gull, note the similar mantle colour
adult Caspian Gull, front-centre, showing amongst other features small white head, small dark eye, washed out bill, anaconda neck and long legs
the same bird
Yellow-legged Gull in the Cuckmere
by now the light was truly awful
 Sunday 18th. A misty day so I didn't venture far. Hardly anything at Shoreham Fort/Harbour and 2 Little Grebes and an argentatus and a colour-ringed Herring Gull on the Adur. 
Lancing College in the mist
argentatus Herring Gull and 'ring-billed' Common Gull on the Adur
North Thames Herring Gull S8WT on the Adur

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