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        Discussion Area 討論區 >> Photo Gallery 相片分享 I >>  Black-tailed Gull 黑尾鷗 &nbsp;
        
(Message started by: Hendrix on Dec 27^th, 2005, 10:55pm)

Title: Black-tailed Gull 黑尾鷗  
Post by Hendrix on Dec 27^th, 2005, 10:55pm

FIRST WINTER ? ???

#1
http://www.hkbws.org.hk/fileServer/PhotoG/hendrix/hendrix_185.jpg
http://www.look.com.hk/wings/gulls/btailed/004.jpg

#2
http://www.hkbws.org.hk/fileServer/PhotoG/hendrix/hendrix_186.jpg
http://www.look.com.hk/wings/gulls/btailed/005.jpg

AFS600/4 + 1.4X on D2X , 1/1000 , F5.6 , ISO 500

27/12/05 NSW

Title: Re: Black-tailed Gull 黑尾鷗
Post by JanJ on Dec 28^th, 2005, 6:32am

Hi Hendrix!

Does not look like a Black-tailed Gull of any age.
Take a look at these:

http://larus.hp.infoseek.co.jp/a_Bt-G.html

I think it is one of the large white-headed gulls, probably mongolicus.

Last image here:

http://vegae.hp.infoseek.co.jp/MonJ_2wYam/MonJ_2wYam.html

JanJ

Title: Re: Black-tailed Gull 黑尾鷗  
Post by Anton on Dec 28^th, 2005, 6:52am

Hi JanJ~

Or could it be a Vega gull? ???

Anton

Title: Re: Black-tailed Gull 黑尾鷗
Post by JanJ on Dec 28^th, 2005, 7:53am

Well, it could I suppose. I think that the rather lightly streaked head, (it is December) with streaks/spots confined to the neck, rather similar to a cachinnans, and the somewhat parallel shaped bill, with a well defined black tip, is good for mongolicus. As always identification is tentative, due to variation (!), but it could well be a vegae, but there is a mongolicus feel to it.

JanJ

Title: Re: Black-tailed Gull 黑尾鷗
Post by gjcarey on Dec 28^th, 2005, 10:42am

I do not think this is mongolicus. The mixture of varying age (different patterns and colours) feathers indicates that this is not a first-winter bird. That given, then it cannot be mongolicus, which shows a clean pale grey mantle in second winter plumage, with largely white underparts and tail, the latter with a varying though usually rather narrow tail band. Mongolicus in its first winter does not replace very many coverts at all, usually just a small number of inner wing coverts by the end of the winter.

My suspicion is that this is a second-winter HK heuglini. This carries out a more or less continuous moult through its first winter and into the first summer, which results in this rather variegated appearance to the upperparts in the second winter. The tail band is still broad and blackish though, which is a good indicator of heuglini. And is that one or more pure and fairly dark grey feathers in the middle of the secondary median coverts on the left wing?? The inner primaries are a little pale, which might suggest some vegae influence.

Regards,

Geoff

Title: Re: Black-tailed Gull 黑尾鷗
Post by JanJ on Dec 29^th, 2005, 12:18am

No, not a 1st winter bird of course, and the plain looking greater covert pattern would perhaps not be so good for 2nd winter type mongolicus. like this:

http://www23.tok2.com/home/jgull/051118/mongolicus2w.htm

JanJ