Saturday, 22 January 2011

Tip top

This second-winter Yellow-legged Gull was one of eight on the landfill site during the latest sesstion.

A good day for recording colour rings, with 15 Herring Gulls (mostly local birds) photographed and logged.
This Herring Gull, UR8T, was ringed at Pitsea, Essex, on 6 March 2010 and seen again on 6 August 2010 at St Maartenszee, Noord-Holland, Netherlands, before reappearing on the Thames at Rainham last Friday.
Another day passes, and still no sign of the Slaty-backed Gull. I put in a good six hours at Rainham on Friday, and estimated from my elevated position that at one time somewhere upwards of 10,000 gulls were on view on the landfill, Wennington and the reserve. Black-headed and Herring accounted for the majority, but there were large numbers of Common Gulls one the tip as well and Lesser Black-backeds seemed numerous too. Great Black-backeds probably numbered 200+ but I didn't make any counts other than Yellow-legged Gull (eight) and Caspian (just a single first-winter), focusing instead on trying to dig out the Slaty-backed and anything else that looked interesting.


The Glaucous hybrid reappeared in the mêlée to give good views. Note the distinctive flight-feather pattern, showing only as brownish on the outermost primaries on the upperwing and as silvery-white on the underwing.

Interesting tertial pattern, surely ruling out the possibility of this bird being a pale Herring Gull, as one person (who has not seen the bird) has claimed. Note also the very pale and marbled greater coverts.

Close-up of the same bird's secondaries, which are mainly white with
limited darker brown internal markings, and barred rump.
Amazing then, among that vast larid swarm, to have seen two individual gulls again that I found on Wednesday. The first was the Glaucous hybrid (above), a distant beast initially but now seen in flight for the first time. The exact pattern and shading of the primaries appear to confirm it is the same bird.

Also reappearing was this dark first-winter gull, which has a number of features suggestive of American Herring Gull (including black tail, strongly patterned rump and uppertail coverts, dark greater covert bases and narrow tertial edges), but which is believed more likely to be a so-called 'Finnish' argentatus bird. Further opinions have been sought.
Another second-shower, right in front of me this time, was the odd dark first-winter gull. This fascinating bird, with its smooth smoky-brown plumage tones, is in some respects strongly reminiscent of American Herring Gull, and this shot of the vent and undertail shows it is more heavily marked below than previously appreciated. However, despite some support for smithsonianus, initial feedback from elsewhere suggests it is most likely to be a dark argentatus. I hope to post on this bird again in due course, but it is very distinctive in the field and, in my opinion, in need of further examination.

The dark eye of this gull immediately gives its a look recalling Thayer's, but the orbital ring is yellow and it is presumably just an aberrant Herring Gull. Unfortunately, the spread wing pattern was not clearly seen.
Also causing brief excitement was a Herring-type gull with a dark eye that was on show for just seconds and then lost in the throng. I'll keep a look-out for this next week ...

UPDATE This blue-ringed 4cy Lesser Black-backed Gull is a Belgian-ringed bird. Thanks to Nathalie Mahieu for assistance in attempting to decipher the code - enquiries are ongoing with the ringing scheme.

3 comments:

  1. For the blue ring, I'd say it looks like NXAH, to be read upwards, fitting a Belgian scheme.
    HTH
    Nathalie

    ReplyDelete
  2. Merci beaucoup, Nathalie - I will email you a marginally better image of the ring in case that helps confirm the details. You're clearly better at this than me!

    ReplyDelete
  3. http://gull-research.org/lbbg2cya/hnam.html

    ReplyDelete

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