Sunday, 7 July 2013

Crossness strikes again

Adult (or second-summer) Bonaparte's Gull at Crossness, London, today.
I ended my post yesterday with the stop-press news that a Bonaparte's Gull had been found on the Inner Thames at Crossness. It was still present today, so I had to make the awkward cross-city journey to 'sarf' of the river to spend some time with this third-ever London bird. And what a peach it was too.

The black hood reaching further down the nape and around the throat, as well as the shorter and more slender black bill and smaller size, are clear distinctions from Black-headed Gull (behind).
Bonaparte's Gulls in full breeding plumage are rare in Britain, most being seen in winter or spring - or, in the case of the long-staying bird this year at Oare Marshes, Kent, as first-summer (2cy) birds. There is speculation that the new arrival at Crossness may actually be a second-summer (3cy) on account of the tiny speck of black in its primary coverts.

The pale under-primaries are just about visible in this shot. Note also the pinkish-red legs.
The two previous London records of Larus philadelphia both also come from Crossness, and were as recent as spring 2012 (an older record, previously accepted, is now under review and expected not to survive). Might this latest bird be one of those two returning? The finder of the 2012 individuals, Rich Bonser, was there today at the gathering for this adult, as were Jono Lethbridge, Mick Southcott, John Archer, James Lowen and many others. While Rich and I were chatting, the finder of the latest Bonaparte's, Mike Robinson, also appeared. He played down the find, putting it down to luck, but should be very pleased with discovering such a notable American vagrant in arguably the month it is least expected to appear.

Obvious here in the centre of the frame, the Bonaparte's could sometimes go missing among the large and mobile gathering of adult and juvenile Black-headed Gulls at the sewage outfall.
This record is a reminder that Crossness is right up there with Rainham and Beddington as one of the top three gulling sites in London. As well as the three Bonaparte's Gulls I was fortunate to see the Franklin's Gull present here in April 2000 - neither species has yet appeared at Rainham or Beddington, though both have their own claims to fame. Such birds are a reminder to keep looking at gulls throughout the year, and to never give up.

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