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| Atlantic Gull - Whisby 22/11/2009 http://www.lbcarchive.co.uk/forum/viewtopic.php?f=3&t=17221 |
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| Author: | Edmund Mackrill [ Fri Jul 20, 2012 5:55 pm ] |
| Post subject: | Atlantic Gull - Whisby 22/11/2009 |
Whilst studying Yellow-legged Gulls in the Bird Guides Iris album I came across a photo by Russell Hayes that clearly was not a typical Yellow-legged Gull ( Larus michahellis michahellis) but which shows strong characteristics of Atlantic Gull (Larus michahellis atlantis ). I contacted Russell and he sent me a couple of the original photos from Whisby 22/11/2009 . Russell has now posted a photo of the Gull for me to comment on. Interestingly, Collin Jennings photographed the same bird on the same day and posted the photo in the Forum Photo Album at the time!. As can be clearly seen this bird has the typical extensive head streaking of Atlantic Gull, although less extensive than pure Azorean forms, it falls well into the range of other Atlantic birds - michahellis typically has very limited head streaking in winter. The mantle colour is certainly at the darker end of typical michahellis and fits Atlantic Gull which typically has a darker mantle. The tibia is noticeably short as is the primary extension - both characteristics of Atlantic Gull. Whilst showing a pale eye I feel this is indeterminate. The bill is relatively short and heavy, again fitting Atlantic Gull. Primary pattern cannot be fully seen but what can be seen is ok. This may be the first record of this sub sp for Lincs. All comments most welcome. Thanks Russell. Edmund |
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| Author: | Grahame Hopwood [ Fri Jul 20, 2012 9:28 pm ] |
| Post subject: | Re: Atlantic Gull - Whisby 22/11/2009 |
Although Ed was quite right to flag this bird up on the strength of that one photo, we however believe that this Larid represents a Yellow-legged Gull of the form michahellis. This particular individual turned first turned up on 11th Nov 2008 on Grebe Lake but quickly re-located to Thorpe Lake where it roosted every night on one of the small islands until 9th Jan 2009. The same bird then re-appeared later in the year on 3rd Nov and wintered until 27th Jan 2010. The bird did show quite dense streaking around the eyes/face we did discuss this on a couple of occasions whilst watching the bird, particularly in light of the near adult atlantis that had turned up in Oxfordshire during Oct 2009. However this does appear to be within the range for michahellis. Indeed Olsen and Larsson comment that ‘ head often with fine brown streaking especially on crown and ear coverts’ The illustration on plate 39 shows a adult winter michahellis with a head pattern not too dissimilar to that of the Whisby bird but falls short of the ‘heavily dark spotted head creating a hooded appearance’ typically found on atlantis. DN has seen several Yellow-legged Gulls in late autumn/winter with head streaking as prominent as this bird. The apical spots looked a bit small for atlantis (though there is variation) and the mantle tone was not actually as dark as Russell’s photo suggests, as this was taken on a very dull overcast day (DN was stood next to him at the time!). In addition the wing tip pattern on this bird was also consistent with michahellis. Finally this particular gull was an absolute monster being close in size to a Great Black-backed Gull. For this reason and coupled with its aggressive nature it was known affectionately as Brutus to local birders! Regards Grahame Hopwood Dean Nicholson |
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| Author: | Edmund Mackrill [ Fri Jul 20, 2012 10:53 pm ] |
| Post subject: | Re: Atlantic Gull - Whisby 22/11/2009 |
Fascinating. Thanks for your post Graham - size was the one character that I could not determine. However, I still think that birds showing this plumage and structure are not true michahellis ( for the reasons I describe )and are probably of Atlantic Coast origin and atlantis shouldn't be ruled out just because a bird does not show 'full' Azorean atlantis characters. Olsen refers to considerable variation within the large range of atlantis. I shall do more research, especially as I'm going to be on the Atlantic Cost of Iberia in September. You never know with Gulls!! |
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| Author: | Freddy Johnson [ Sat Jul 21, 2012 9:05 am ] |
| Post subject: | Re: Atlantic Gull - Whisby 22/11/2009 |
Congratulations to Ed, Grahame and Dean N. for 3 interesting and educational posts of the type that help to imbue our LBC website with quality plus knowledgeable and analytical (adult) comment. I'm not a great Larid fan myself but couldn't help but read the 3 posts more than once so as to fully appreciate the pro and anti discussion points and reasoning involved....certainly not posts to be skimmed rapidly....  Freddy |
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