HKBWS BBS 香港觀鳥會新聞組


    
      
        HKBWS BBS 香 港 觀 鳥 會 新 聞 組
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        Discussion Area 討論區 >> Bird Identification 鳥類辨識 >>  Herring gulls 銀鷗
        
(Message started by: Hendrix on Apr 16^th, 2005, 12:17am)

Title: Herring gulls 銀鷗
Post by Hendrix on Apr 16^th, 2005, 12:17am

http://www.look.com.hk/wings/gulls/herring/001.jpg

http://www.look.com.hk/wings/gulls/herring/002.jpg

Vega ??? yellow leg ??? or same ???

D2X , AFS600/4 +1.4x , f7.1, 1/1250s, ISO 400

Mai Po Nature Reserve, Hong Kong 米埔
29/03/2005

Title: Re: Herring gulls 銀鷗
Post by JanJ on Dec 23^rd, 2005, 8:26am

Hi Hendrix!
Difficult area, identification tentative, but the first one looks like a so called
vegae x taimyrensis. Lightly streaked only in the neck region, and not so bright yellow legs. Still moulting primaries at this time of year (p10 not fully grown) indicates heuglini (vegae x taimyrensis) or vegae.
Second one looks like a vegae, heavely streaked, but more obvious in the neck. Dark around eye with a dark line in front, and behind the eye and rather pale iris reminds off schisisagus, but also vegae, together with underwing pattern and late moult.

http://www.magikbirds.com/image.asp?title_id=509&show_thumbnails=False

http://www.surfbirds.com/ID%20Articles/JapanGulls/index.html

http://user.chollian.net/~aves/news/0502/news050204-heugull.htm

JanJ

Forgot to mention, very nice images!

Title: Re: Herring gulls 銀鷗
Post by Anguslau on Dec 23^rd, 2005, 12:18pm

Very nice images indeed! Look forward to seeing them again soon. :D

Title: Re: Herring gulls 銀鷗
Post by gjcarey on Dec 28^th, 2005, 10:16am

Both photos were taken at the end of March, and both birds show uncompleted primary moult. This indicates that neither bird can be pure vegae, whose primary moult is generally complete by late December or January, aside from exceptional (sick) individuals.

The first bird looks like classic HK heuglini to me. The late date is the cause of the very restricted head streaking and the brighter, more orange tone to the legs (the feet in particular). The head and neck do not have the bulk and size that I associate with vegae, and there is a single mirror on p10. I see no pro-vegae features in this bird at all.

The second is a hybrid of vegae and heuglini. As Jan says, the pinkish legs and heavy neck streaking indicate vegae; in addition, the lengths of head and bill also point to that species, as does the second mirror on p9. However, the moult is incomplete, and so late in the winter this must indicate introgression of vegae genes. It would be interesting to have seen the upperpart coloration in comparison with the typical heuglini we get here. This bird is actually pretty close to vegae, but the moult is problematic.

If one calls this vegae x heuglini individual 'taimyrensis', then this it what it is, though personally I'm still unsure what the birds in HK are. I know what they look like, but I don't know what they are.

Geoff