Friday, 16 March 2012

White-winged bedlam

Second-winter Kumlien's Gull (left) with adult Lesser Black-backed Gull of the subspecies graellsii.
The dark pigmentation in the primaries tips was not always obvious when the bird was perched, even at close range.
With temperatures edging into the high teens this week and the first summer migrants arriving in numbers in southern England, it feels like the gulling season is drawing to a close. So only one thing for it: give it a final go! This morning was going to be my last chance for a couple of weeks, so before most of the winter's birds ship out I headed over to Rainham Marshes as much out of duty as expectation.

Good move, however ... within five minutes of arriving I picked up a white-looking gull loafing among the Herrings and Lesser Black-backeds. Despite numerous visits to the Thames this winter I hadn't scored any large white-winged gulls, and had resorted to twitching Beddington on the other side of town to get a fix of its Icelands. I therefore almost expected this stand-out individual to be the famous leucistic Herring Gull that bears the ring number SH1T - an occasional visitor to Rainham (and also Beddington). Instead, when I got the bins on it alarm bells rang immediately - this was clearly an Iceland-type, but looking at it rear on there was obvious dark pigmentation on the white-edged outer primary tips: it surely had to be a Kumlien's Gull.

Note the 'airbrushed' dark outer webs to the four outermost primaries in particular, and the contrast to the whiter inner primaries, as well as the strong tail band.
At range, the darkest area of the wing was actually the greater coverts, in contrast to its appearance at rest.
Before long the gulls got up, and the pattern of the open wings and spread tail was even more striking - see the images and captions above. This bird fitted the 'search image' I had since watching a second-winter Kumlien's in Ireland early last month; I was also well primed for such a bird after editing an excellent article by Peter Adriaens on separating Iceland and Kumlien's Gulls for April's Birdwatch - coincidentally published  today. Perhaps this bird was just meant to be.

I put a call in to David Callahan at the Birdwatch office to run through the features with references to the article and fully confirm my ID before putting the news out. As we were speaking, a white gull flew through the throng and I paused the conversation to eyeball it - second-winter Iceland Gull! Apologies to David for the abrupt end to the call, but the result is a few more images to enjoy:





After a lull in proceedings, I twice got distant and very brief views of a more adult-like white-winger. From the poor record shots below it looks like a third-winter, but what, exactly? There is a hint of darkness in the outer primaries and Andy Tweed told me today that there was a sub-adult Kumlien's briefly at Rainham this week which, like this bird, had a slight dark mark on the bill. Steve Arlow apparently had a similar bird over at Pitsea, only 13 miles or so downriver. I put the news out as Iceland or Kumlien's, pending better views or photos by others, but two comments so far have also suggested leucistic Herring. What do you think?

Third-winter gull over the stone barges today. Could this be the bird reported as a Kumlien's Gull, or is it even just a leucistic Herring Gull, as suggested by others?
In this shot the outer primaries appear slightly darker, but tinged brownish - shame it was so distant.
Finally, no such problems with this spanking adult Iceland Gull, another welcome find which showed very well but briefly today:

Adult Iceland Gull - the fourth and final white-winger of this morning's unprecedented session.
For the number of rare arctic gulls present at Rainham I've never known a day like it - especially as Dave Darrell-Lambert also had a first-winter Iceland Gull at the barges. Of the four birds that I found, the second-winter Kumlien's and the adult Iceland appear to be new birds, while the rather large second-winter Iceland and the third-winter Iceland/Kumlien's are most likely individuals already reported recently. In addition, I have some very distant images of an Iceland from today which may relate to a different second-winter bird - no time to analyse them now, but watch this space.

My final gull list for the morning: 2w Kumlien's Gull, 2w and ad Iceland Gulls, 3w Iceland or Kumlien's Gull, 1w Caspian Gull, ad and 1+ 2w Yellow-legged Gulls, and good numbers of Herring Gull, Lesser Black-backed Gull, Great Black-backed Gull, Common Gull and Black-headed Gull. That's an acceptable haul for one morning. Let's sign off with that Caspian (the last of the winter?):

A first-winter Caspian Gull makes a brief appearance in the crowd.

6 comments:

  1. Wow Dom, what a day! Fantastic gulling session and cracking shots, seemed like it was probably a very hectic afternoon!!

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  2. Another great find, Dom. Rather better views than we had on wennington this afternoon

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  3. Thanks for the kind comments, and glad you both managed to catch up with it - James, if you get another chance to visit Rainham perhaps it will reappear at the barges, where it showed quite well (remembering that sometimes white-wingers stick around until early April)

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  4. The second winter bird looks different to the three (plus a 1/2w) we've had at Beddington Dom. Being able to see a few this winter has reminded me that Iceland Gulls are just as variable as other Gulls. I'm fairly certain the 2w Kumlien's we had today is the bird you had, it didn't come that close. Looking forward to seeing some more.

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  5. ps have you ruled out leucistic Herring Gull for the distant 3w type Iceland Gull ? We've had something similar at Beddington recently that resembled an immature white-winger.

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  6. Glad you got the 2w Kumlien's Gull, Johnny - two Kumlien's in one winter at Beddington is good going! Rich Bonser wondered whether the 2w could actually be the Dover bird relocated - currently in Azores and haven't had time to check pics in detail, but have a look and see what you think. Interesting to hear the 2w Iceland is probably different to the birds you've had at Beddington. I did photograph the same or another 2w very distantly on the same day which may possibly be different to the one shown here, but I've only got record shots of it perched so not sure. The 3w type could quite possibly be Herring, as someone else pointed out - poor pics and photos and not seen again by me, unfortunately!

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