Viking Gull or Thayer's Gull in Denmark?

User avatar
JanJ
Posts:437
Joined:Mon Oct 12, 2009 10:08 pm
Re: Viking Gull or Thayer's Gull in Denmark?

Post by JanJ » Sat Mar 31, 2012 4:49 pm

I should probably hold my tongue, ;) since Peter comes up with yet another good example of how a thayeri can look. The variation - in this case in 1st cycle thayeri is probably more extensive than birders normally might think. The axillarie barring in Peter´s thayeri approaches the ones shown by the danish bird, although not so extensively.

Thanks for that image Peter, no doubt there´s more to come...

JanJ

adriaens
Posts:229
Joined:Sun Sep 27, 2009 9:24 pm

Re: Viking Gull or Thayer's Gull in Denmark?

Post by adriaens » Sun Apr 01, 2012 3:21 pm

Underwing of one of the birds from my post on 30 March:
ThayersGull_1c_Monterey_CA_20110201_020.JPG
ThayersGull_1c_Monterey_CA_20110201_020.JPG (75.57KiB)Viewed 6026 times
Some more underwings from California:
Attachments
ThayersGull_1c_HalfMoonBay_CA_20110119_010.JPG
ThayersGull_1c_HalfMoonBay_CA_20110119_010.JPG (423.53KiB)Viewed 6026 times
ThayersGull_1c_BodegaBay_CA_20110127_077.JPG
ThayersGull_1c_BodegaBay_CA_20110127_077.JPG (70.17KiB)Viewed 6026 times
ThayersGull_1c_BodegaBay_CA_20110127_074.JPG
ThayersGull_1c_BodegaBay_CA_20110127_074.JPG (51.44KiB)Viewed 6026 times
ThayersGull_1c_BodegaBay_CA_20110127_050.JPG
ThayersGull_1c_BodegaBay_CA_20110127_050.JPG (47.85KiB)Viewed 6026 times

User avatar
Hans Larsson
Posts:47
Joined:Tue Nov 24, 2009 9:49 pm

Re: Viking Gull or Thayer's Gull in Denmark?

Post by Hans Larsson » Sun Apr 01, 2012 8:14 pm

Further different Thayer´s gulls from CA for comparison. I would be baffled (or depressed, really) if a hybrid could come up with the set of features that Kent´s bird shows..
Attachments
thay6.JPG
thay6.JPG (365.83KiB)Viewed 6020 times
thay5.JPG
thay5.JPG (410.43KiB)Viewed 6020 times
thay4.JPG
thay4.JPG (448.93KiB)Viewed 6020 times
thay2.JPG
thay2.JPG (392.02KiB)Viewed 6020 times
thay3.JPG
thay3.JPG (175.02KiB)Viewed 6020 times
thay1.JPG
thay1.JPG (159.43KiB)Viewed 6020 times

User avatar
JanJ
Posts:437
Joined:Mon Oct 12, 2009 10:08 pm

Re: Viking Gull or Thayer's Gull in Denmark?

Post by JanJ » Sun Apr 01, 2012 9:47 pm

Nice pic from Hans and Peter! Especially pic 4 by Hans - which shows similarities to Kent´s bird regarding face pattern
And yes, why worry about a certain facial expression and size of head, amount of bleching and such things, when everything else seems to be in place for a thayeri 8-)

JanJ

User avatar
Hans Larsson
Posts:47
Joined:Tue Nov 24, 2009 9:49 pm

Re: Viking Gull or Thayer's Gull in Denmark?

Post by Hans Larsson » Sun Apr 01, 2012 10:35 pm

I should add that my birds are November-December ones, for the record.

User avatar
marsmuusse
Posts:666
Joined:Sun Sep 27, 2009 12:43 pm

Re: Viking Gull or Thayer's Gull in Denmark?

Post by marsmuusse » Mon Apr 02, 2012 6:53 am

I think an important feature can not be determined very well from the images: size of the bird. Maybe Kent has an 'overview' picture, or maybe he can tell from what he experienced in the field. There are two images in his set on the blog:

- one picture where the bird looks strikingly small (hyperboreus-like bird in the background).
Image

- one in which it comes pretty close to a Herring (assumed nominate argentatus on location?). Here, it obviously lacks the bulbous tip, still we do not know the sex of the Herring and that might have been a huge male for instance.
Image

User avatar
Hans Larsson
Posts:47
Joined:Tue Nov 24, 2009 9:49 pm

Re: Viking Gull or Thayer's Gull in Denmark?

Post by Hans Larsson » Mon Apr 02, 2012 8:38 am

Another view of Thay4 from my previous post, to compare underpart mottling.
Attachments
thay4-2.JPG
thay4-2.JPG (178.81KiB)Viewed 6005 times

Kent Olsen
Posts:46
Joined:Wed Dec 02, 2009 11:07 pm

Re: Viking Gull or Thayer's Gull in Denmark?

Post by Kent Olsen » Mon Apr 02, 2012 2:24 pm

Unfortunately there are no overview photos beside what is apparent in these photos which you have seen before: http://gulldk.blogspot.com/2012/04/poss ... -gull.html

However, now posted in a completely un-cropped version I hope that you can have some kind of impression by comparing with the jizz on accompanying large gull, i.e. wing span, rump width, head shape, body size etc.

The Glaucous Gull behind the discussed gull was of average and obvious much larger in overall size; it is not only due to the telephoto lens effect. In comparison with Herring Gulls the discussed gull was judged to be within their smaller size and jizz range, thus being a smaller and slimmer type of Herring Gull. This actually conflicted in my mind as I at that time found it hard to believe that genetic influence from Glaucous Gull would produce a slimmer and smaller than average Herring Gull-sized Viking Gull.

Based on the large series of great photos from e.g. Peter Adriaens and Hans Larsson I personally believe that the proportions and size of the Danish gull fits well within the larger Thayer’s Gulls. However, I need to stress that my considerations are based on the assumption that the photo material illustrates pure Thayer’s Gulls and not any of hybrid origin.

While photographing two Iceland Gulls at close range, the Danish gull suddenly landed between the other gulls. I was stunned by its plumage and general colour and thus shot a series of photos, but it didn’t stay for long before it went to a nearby roof from where it within minutes was scared off again by factory workmen and then couldn’t be relocated.

Based on my narrow search image on Thayer’s Gull, I evaluated the photos on the camera display and concluded that it was a scary hybrid and not the real thing even though several impressions kept roaming. The head profile changed dramatically between when it stood relaxed on the roof with a rather round head and gentle expression and when it feed with its wings continuously raised while balancing on the container edge and in constant combat with the nearby large gulls as in most photos.
Attachments
_MG_6290.JPG
_MG_6290.JPG (241.32KiB)Viewed 6001 times

User avatar
Hans Larsson
Posts:47
Joined:Tue Nov 24, 2009 9:49 pm

Re: Viking Gull or Thayer's Gull in Denmark?

Post by Hans Larsson » Mon Apr 02, 2012 8:54 pm

During my trip to central CA in early winter 2010 I saw very few Thayer´s gulls, so I had plenty of time to carefully eliminate other possibilities for the birds posted here. IMO, despite the Pacific coast being seriously hybrid-infested, the species is generally very straightforward to ID when seen well.

Kent Olsen
Posts:46
Joined:Wed Dec 02, 2009 11:07 pm

Re: Viking Gull or Thayer's Gull in Denmark?

Post by Kent Olsen » Fri Apr 06, 2012 9:56 pm

I have made a series of collages which makes direct comparison with Thayer’s from California and Japan possible. To evaluate the finer details please remember to click on the photos as they will expand to full size.

http://gulldk.blogspot.com/2012/04/thay ... -with.html

Does everybody agree on the identification?

Kent

Post Reply