Monday, January 4, 2010

Probably not a European Herring Gull-? Vega Gull

I got a quite a few positive responses in regards to the possibility of this bird being a European Herring Gull- L. a. argentatus. Alas however the two not so positive responses were the most elucidating. These comments revealed to me the true importance of actual extensive field experience with the species in question.


Former candidate for first winter European Herring Gull


 Hans Larrson (Olsen & Larsson- Gulls of North America, Europe and Asia) kindly reviewed the pictures and forwarded some very enlightening comments as well as some very detailed pictures.

Here are Hans comments


"Back to your bird then. Compared to the average argentatus in southern Sweden (with many Arctic birds arriving now), it differs in:


*Bill colour - The vast majority has a quite dark bill during the first year, although birds with bicolored do occur regularly.


*Body colouration - Normally the underparts are not so uniform. We always keep an eye out for this type of pattern, while searching for American Herring and Thayer´s Gulls, that has yet to be recorded here. Usually, we fail to find birds with such neat colour.


*Wing coverts (and scapulars, to a lesser extent) - They seem paler and very neat and tidy patterned compared to the darker and quite messy ones in argentatus.


*Leg colour - This deep reddish tone is unusual in our argentatus. Normally they are duller with a greyish tinge.


All in all, my opinion is that your bird much better matches Vega Gull. I enclose a selection of argentatus from my local patch this weekend, to illustrate my reflections. My intention is to eventually post them on my blog (that I run with Jörgen Bernsmo), but with Christmas approaching it may take a while.. "


Hans Larrson


Hans Larrson's great blog- http://truthjalpen.blogspot.com/search/label/Larus%20argentatus

Lets go through this point by point

Bill colour- I don't think the bicolour bill on my bird is a decisive point. It seems to be present uncommonly in L. a. argentatus and is clearly seen in L. a. smithsonianus.

Body colouration- This is probably the single most diagnostic point in my mind going against L.a. argentatus.




First winter European Herring Gull -Hans Larrson

The above picture was taken by Hans Larrson in Sweden this past December. It clearly illustrates the heavily streaked chest and belly. My bird below clearly differs with a neat uniform chest and belly as well as lightly vermicullated flanks.


My First winter "Herring Gull"

The flanks on the following L.a . argentatus from Sweden are much heavier marked with blotchy bold patterning.



First Winter European Herring Gull- Hans Larrson

On to the wing coverts. Hans comments - They seem paler and very neat and tidy patterned compared to the darker and quite messy ones in argentatus. Indeed my birds coverts are quite precise.



My first winter "Herring" Gull


First winter European Herring Gull- Hans Larrson

Above Hans L.a.argentatus clearly has messy coverts quite distinctive from my bird. However the folllowing bird which is also a Swedish  L. a. argentatus really seems to be remarkably similar to my bird with maybe just a touch messier coverts very similar mantle feathers and rather uniform underparts.




















First winter European Herring Gull-Hans Larrson



My first winter "Herring" Gull

Well the leg color on all of Hans birds is as he describes - dull greyish pink. My bird definitely has brighter pink legs and that was noticeable in the field and in comparison with the other first year Herring Gulls at the scene.



My first winter "Herring Gull" to the right

I think the above photo illustrates well this birds relatively bright pink legs. In the field they were noticeably brighter than the other first year 'Herring" Gulls.

The well known Dutch birder and gull expert Peter Adriaens also was kind enough to comment on this bird via ID Frontier's:


"At the risk of sounding overly critical, I think there are still several subtle features that do not look entirely convincing for European Herring Gull.
Perhaps too much importance is placed on the paleness of the plumage and the barred look of the wingcoverts and tertials, but not enough on the tail pattern and pattern of the underparts.


First though, there is the bill pattern. While it is true that a bicoloured bill in itself is not an issue for argentatus, the pattern is only rarely as clear-cut and Glaucous-like as in this bird. In most European HGs, the black colour of the bill tip continues along the mandibles towards the base.
To my eyes, the tail looks a bit unusual for European HG in that the outermost tailfeathers appear so densely barred right up to the feather bases. In European HG, the dark bars on the outermost rectrices are typically sparse or widely separated, creating the impression of rather white outer tail bases. I don't know if there is a need for more comparison flightshots of European HG on the internet, but have uploaded mine:


Peter Adriaen's



My first winter "Herring" Gull




First winter European Herring Gull - Hans Larrson




First winter European Herring Gull - Hans Larrson


Peters comments on the barring of the outer retricies and tail pattern are well demonstrated in the above pictures. A quite convincing difference between my bird and the two examples of L.a. argentatus sent to me by Hans Larrson.  Peter's link shows many other examples supporting his point.


After reviewing Hans and Peter's comments and the pictures I felt fairly convinced my bird was not a European Herring Gull. Clutching at the last straw I reviewed every picture in the books and on the net of first winter Vega Gulls. I also sought out opinions:


Brandon Holden remarked that "those familiar with Vega noted that they are a"Northern" Gull, retaining juv. plumage for a long time. My bird, and yours, were both perfectly molted into 1st basic plumage, something that would be odd for Vega by this date."


On reviewing the multiple first year birds on Ujihara's "Japanese Gull Site"-

http://larus.hp.infoseek.co.jp/gullidentifi_.htm

It was apparent that most (but not all) Vega Gulls retained their juvenile plumage well into the winter. I could also not find a bird in the early first winter of life with such a frankly bicolored bill. However some of the late winter birds had very similar bills. The tails of Vega Gulls were very similar to my bird as were the bright pink legs.

I did send the pictures off to a couple individuals with extensive experience with Vega Gull and if they respond I will do a further post.

Probably the wisest advice I got on this bird was from gull guru Bruce Mactavish:

"While your bird doesn't fit the typical image of smithsonianus I don't think it is safe to automatically assume it has to be European or Eurasian.  I don't think we know the limits of smithsoninanus in central
North America especially. Maybe later I will send a few shots from late Sept 2009 in Red Deer.  Identifying gulls using the process of elimination is dangerous.  Even now saying it is a probable Vega because it doesn't appear to be a Euro Herring is also unsafe.  We need to know what a Vega really looks like too.



Backburner birding. Gulls like that are best left on the backburner
until we learn more."





Sound advice.

 I would sure like to hear from anyone with experience with Vega Gulls.

Kirk




5 comments:

  1. Hi Kirk,
    I fully agree with the conclusion that it´s most probably a smith until one can really prove another possibility. Also, as mentioned in your post, several features are not in line with Vega Gull. Individual variation is enormous and it´s easy to under-estimate the extension of this at times..

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  2. Hello Kirk.

    I agree with Hans and Peter that your gull is most probably not an European Herring for the reasons they mentioned. Excluding, or suggesting a Vega Gull is a real challenge - as is the separation of many American from European herring Gulls. In the pic. above the one labeled 'My first winter Herring Gull to the right' the darker (although on a pale bird), rather uniformly patterned neck and upper mantle and underparts hints the wellknown pattern of American Herring.
    As can be seen in these Vega moult score is quite different in Dec. Also note the rather uniform pattern on upper mantle and underparts in some which could invite to confusion with American Herring.

    cheers

    JanJ

    http://www23.tok2.com/home/jgull/071222/vegagull.htm

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