Slaty-backed in the UK?

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pim wolf
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Slaty-backed in the UK?

Post by pim wolf » Fri Jan 14, 2011 12:18 am

like Dominic write's: "It's been one of those days..."

Full story here: http://www.birdingetc.com/2011/01/candi ... ondon.html

pim

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Theo Muusse
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Location: Dordrecht

Re: Slaty-backed in the UK?

Post by Theo Muusse » Sun Feb 20, 2011 8:28 pm

I love the forum about this bird.
Combining all features to make it one has not happened yet!

Surely its one, but do they think so too?

Theo

grzegorzneubauer
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Slaty-backed or what???

Post by grzegorzneubauer » Mon Feb 21, 2011 9:46 am

Hi All,
have just wanted to start a new topic, but thx to Theo's reply discovered that it already is here...
Pls have a look on that bastard I photographed yesterday at my favourite coastal site - Wladyslawowo, N PL (some of you may still remember the place from the 2003 IGM)
Not surprisingly, initial thoughts went to schistisagus (esp. that I have looked at the UK one recently too many times), but after careful studying of pics, I must admit there are at least few things that don't fit. While the wing-tip alone seems to be quite within the variation - see eg fig 12 on page 30 in KMO & HL book and David Erterius pic 38020... from Chukotka in the netfugl gallery - the trailing edge looks (too) thin, and the structure is not the one I would expect (but there are also pics in the web that show them in upright posture, when they look very similar!). Given the variation - which as shortly described in Gulls book seems not to be smaller than in eg HEGU - what is it?
So, the most important things to answer now: (1) no idea on variation, and its studying from not so numerous pics of open wings in the web does not help much and (2) no idea on excluding a hybrid (schist x something or maybe marinus x something pale, eg HEGU?). Any published hybrids of marinus x sth???
See also probable hybrids of schist x glauc : http://www23.tok2.com/home/jgull/HybridGW_SL/ . Similar, uh?
After my emotions have fallen dawn, I'd personally go for SSH ('some sort of hybrid') rather than anything else.
Needless to say: I urgently await your thoughts!
Greg
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grzegorzneubauer
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Re: Slaty-backed in the UK?

Post by grzegorzneubauer » Tue Feb 22, 2011 10:55 am

Really, nobody is able to produce a comment about such an extraordinary bird? no thoughts? pics have been viewed 50+ times since yesterday...
Attached one more showing well the wing-tip from the underside.
Greg
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adriaens
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Re: Slaty-backed in the UK?

Post by adriaens » Tue Feb 22, 2011 11:42 am

Hi Greg,

my first impression from these photos is of a (very) dark, northern argentatus.
Of course, it is possible that there is some influence of Great Black-backed Gull in this bird; who knows...
In any case, it does not look like a Slaty-backed Gull to me.

grzegorzneubauer
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Re: Slaty-backed in the UK?

Post by grzegorzneubauer » Tue Feb 22, 2011 12:20 pm

adriaens wrote:Hi Greg,

my first impression from these photos is of a (very) dark, northern argentatus.
Of course, it is possible that there is some influence of Great Black-backed Gull in this bird; who knows...
In any case, it does not look like a Slaty-backed Gull to me.
Thanks Peter. An option that I didn't consider...
G

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JanJ
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Re: Slaty-backed in the UK?

Post by JanJ » Tue Feb 22, 2011 3:51 pm

Hi Greg.

With such a provokativ gull I´m not surpriced that people hestitate to comment. However, as Peter - I was into a dark argentatus with a possible marinus influence, based soley on the darkness and to certain extent the outer primary pattern, but that is just guesswork at the best.
Although I can see where the possble Slaty-backed thoughts are comming from it´s a long way to Slaty-backed.
So - what do others say 8-)

JanJ

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marsmuusse
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Re: Slaty-backed in the UK?

Post by marsmuusse » Tue Feb 22, 2011 4:35 pm

I think one of the reasons for hesitating to reply is that most of us do not have much field experience with this taxon and the near relatives / hybrids.
What is the variation in taxa that can be found much closer to us, like far northern tatus, pinkish legged taimyrensis, vagae and of course hybrids with SBG? Speaking for myself, I always first have to check the East Asian sites to find what is common stuff there, and then reconstruct the likelyhood of slightly uncommon birds and the chance they turn up here.

There are some pictures which come very close to your bird, like "4 Hybrid Gulls - (Slaty-backed Gull x Glaucous-winged Gull) in Japan" at the Ujihara site:
http://www23.tok2.com/home/jgull/HybridGW_SL/

Like Peter and Jan, my first impression was also argentatus at the darkest end, but when I saw picture a306, it looked really dark? (too dark? unacceptable for argentatus?)

adriaens
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Re: Slaty-backed in the UK?

Post by adriaens » Tue Feb 22, 2011 4:41 pm

marsmuusse wrote: There are some pictures which come very close to your bird, like "4 Hybrid Gulls - (Slaty-backed Gull x Glaucous-winged Gull) in Japan" at the Ujihara site:
http://www23.tok2.com/home/jgull/HybridGW_SL/
I disagree. If you compare the primary pattern, especially the amount of black(ish) on P6-8 and the size and shape of the white mirrors on P9-10, the Polish bird looks very different from these Japanese gulls.

grzegorzneubauer
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Re: Slaty-backed in the UK?

Post by grzegorzneubauer » Tue Feb 22, 2011 5:48 pm

Hi,
thanks a lot and sorry for my impatience! That's something I needed. In the mean time a comment from O & M Ujihara arrived who also exclude a SBG. It is therefore definitely not a SBG while what it is remains unanswered. I heard or read about dark northern argentatus, and have never seen some darker-than-usual birds, but never such outstandingly dark. personally I think it's a bit too dark to easily call it just 'dark argentatus'. It seems to fit some graellsii lbbg in mantle shade, which is clearly darker than kodak 8 given as the darkest argentatus in the Gulls book. And clearly darker than I can imagine any argentatus to be.
well, well, gulls: learning and discovering all the time. and that's fantastic.
Thanx once again,
G.

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