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        Discussion Area 討論區 >> Bird Identification 鳥類辨識 >>  Vega Gull (1st winter) ?
        
(Message started by: KK Hui on Dec 16^th, 2005, 3:41pm)

Title: Vega Gull (1st winter) ?
Post by KK Hui on Dec 16^th, 2005, 3:41pm

http://img.photobucket.com/albums/v22/kkhui/GullTern/161205_77x.jpg

NSW
16/12 2005

Vega Gull 1st winter, anyone?
Thanks!

Title: Re: Vega Gull (1st winter) ?
Post by miket on Dec 17^th, 2005, 9:37pm

Others can speak about gulls with a lot more authority than me, but I think the almost solidly dark tail points to taimyrensis rather than vegae.

Mike Turnbull

Title: Re: Vega Gull (1st winter) ?
Post by JanJ on Dec 18^th, 2005, 1:07am

Hi all!
Because of the rather extensive moult in scapulars and mantle, at this time of year, 'taimyrensis has a later moult, and would normally still have the wast majority of scapulars like a juvenile, fully dark-centered, and the pale inner primaries, which typically would be darker in 'taimyrensis. Therefore I think this is a vegae. The bill seems a little strong for a 'taimyrensis, and together with head creates a structure more in line with vegae, 'taimyrensis often looks smaller headed (sexual differences (males bigger than females) makes it difficult to be sure on this though.The dark tailband is broad and would be a 'taimyrensis' character (which isn´t, at the present, considered to be a valid taxon, but a hybrid between Heuglin´s Gull and Vega Gull) but could fit a vegae as well. The dark greater coverts however, would be perfect on a 'taimyrensis', and seems a bit solidly dark for a vegae, but there is variation, some vegae has very pale greater coverts, with a few narrow dark bars (like many 1st winter mongolicus) some have darker. This one has very dark greater coverts, a slight bother perhaps. My vote is vegae though, but could be wrong.
JanJ

Title: Re: Vega Gull (1st winter) ?
Post by Anton on Dec 19^th, 2005, 3:11am

Hello KK~
Are these pictures of the same gull as yours? I saw it among a big group of black-headed gulls....

http://img.photobucket.com/albums/v225/shark7plus/PICT0059b.jpg

http://img.photobucket.com/albums/v225/shark7plus/PICT0068b.jpg

I also want to know what it is....Thanks! ;)

Nam Sang Wai 南生圍
16/12/2005
Dynax 7D + Tamron 200-500 mm

Anton

Title: Re: Vega Gull (1st winter) ?
Post by gjcarey on Dec 19^th, 2005, 2:06pm

I think this bird is a first-winter Slaty-backed Gull L. schistisagus. The extensively dark tail points to this species, as does the lack of obvious pale inner primaries. A tail as extensively dark as this would be extremely unusual for vegae; similarly, I would expect even a hybrid vegae x taimyrensis to show a less broad dark tail band, as well as some obvious lightening of the inner primaries. The inner primaries appear slightly paler on the photo as a result of the angle of light and the fact that the feathers are fully spread.

The second set of photos provided do, indeed, appear to be of the same bird. On these there are visible rather dark underwing greater coverts, which again is a pro-schistisagus feature. Note the apparently almost complete lack of pale inner primaries on the lower photo.

Feather patterns are rather variable on schistisagus, and it is difficult for me at least to point to anything on this bird that indicates this species. Structurally, however, it appears somewhat stocky, especially around the head and neck, and the bill appears rather thick.

Geoff Carey

Title: Re: Vega Gull (1st winter) ?
Post by JanJ on Dec 19^th, 2005, 10:21pm

Hi all!
I did consider schistisagus, but thought the outer primaries a bit to dark, now thinking the often Thayeri like pattern there. On the other hand the inner primaries does seem a little on the dark side for veage, and the 'patch' does include over half of the primaries. If the second set of images is the same gull, the contrast, dark coverts lighter primaries would be good for schistisagus, as mentioned by Geoff. The images are rather dark, which makes it difficult to see properly. The head does look a bit stocky, and over the neck, true. The dark tail is of course a character of schistisagus, but vegae, although not as often, can have one like this.

http://www23.tok2.com/home/jgull/051108/vegae.htm

JanJ

Title: Re: Vega Gull (1st winter) ?
Post by Anton on Dec 19^th, 2005, 11:38pm

Hi JanJ~

I have tried to re-tuned my pictures....hope they now look better for identification....

Also one more shot here....hope it would be helpful.... Thanks all! ;)

http://img.photobucket.com/albums/v225/shark7plus/PICT0069b.jpg

Anton

Title: Re: Vega Gull (1st winter) ?
Post by JanJ on Dec 20^th, 2005, 2:16am

Hi all,

A trick of the light. On the last image the underwing looks different, there´s an obvious contrast between outer and inner primaries (with no effect like this:http://www.birdskorea.org/images2005/image12juvsbgulwithadmidfebhokky05wingbelow.jpg) and the underwing coverts looks pale, except for a line of lesser underwing coverts,greater, median and lesser primary coverts. On Antons second image, from below, the gull does look schistisagus 'front heavy'. Geoff is probably right in his assumption that it´s a schistisagus. As can be seen here, the different light and angles makes it very difficult to judge certain plumage characters from single images, that would be except for structure though, which do fit a schistisagus.
JanJ