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Subject: [Gulls] Vega Gull 西伯利亞銀鷗 [Print This Page]

Author: ckuifai Time: 13/02/2012 22:23 Subject: Vega Gull 西伯利亞銀鷗

10-Feb-2012
Mai Po 米埔

01

[ Last edited by ckuifai at 18/03/2020 16:57 ]

Author: brendank Time: 13/02/2012 23:37

An excellent set of photos and it is very interesting to see!

This is the type of bird that often gets labeled as Slaty-backed Gulls in Hong Kong. However, to me this bird is not a good fit with Slaty-backed Gull. The structure is not typical for Slaty-backed Gulls. This bird has a rather round "dove"-like head whereas Slaty-backed Gull looks rather block-headed and on this bird the folded wingtips extend rather far past the tail whereas in Slaty-backed that tends to be rather short. Also troubling to me is flecking present on the coverts. While highly variable, on Slaty-backed Gull the coverts typically are more smoothly brown. Additionally, the color tone of the mantle on first-year Slaty-backed Gulls is rather rusty and this feature is completely absent from this bird.

Birds like this seem to me to be a better fit for Vega Gull or least I suspect have some Vega Gull ancestry.

One feature that does seem to point toward Slaty-backed Gull is the rather solid brown tertials. However, the tertials on this bird are heavily worn and there does seem to be some white-fringing to the tertials (which would suggest Vega).

Flight photos of this bird would be very interesting to see if available.

[ Last edited by brendank at 13/02/2012 23:45 ]

Author: ckuifai Time: 14/02/2012 14:57

Brendan, thanks a lot for your very detailed explanation.
Sam

Flight photo :

[ Last edited by ckuifai at 27/11/2015 22:05 ]

Author: ddavid Time: 14/02/2012 21:05

Where did the original pics disappear to?

It's an interesting thread as I'm sure I'm not the only one who finds some of these immature gulls rather puzzling.

David

Author: ckuifai Time: 14/02/2012 21:36

Quote:

Original posted by ddavid at 14/02/2012 21:05
Where did the original pics disappear to?

It's an interesting thread as I'm sure I'm not the only one who finds some of these immature gulls rather puzzling.

David

Sorry for my mistake in moving file of my photo gallery, the pics appear now.

Author: cgeoff Time: 15/02/2012 10:45

While I agree, Brendan, this is most likely Vega, I'm surprised you say this is the type of bird that often gets labeled as Slaty-backed Gull in HK. Is it really?

GeoffC

Author: brendank Time: 15/02/2012 15:13

Yes, maybe a stretch to say that. I made that comment because on three separate occasions I saw and heard birders in the Boardwalk identifying Slaty-backed Gulls which I thought were poor candidates (likely Vega or hybrids involving Vega). Of course, I have no idea whether any of these birds were turned in as records. I think though that there is a danger with a relatively difficult to identify species such as Slaty-backed Gull. Once a few genuine individuals show up people start over identifying it because they now believe it must be "out there".

In any case, that is one of advantages of photography and clearly we are moving in a manner in which more and more photos are available of interesting records.

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