Sunday, October 31, 2010

Adult Vega Gull in Sault Ste.Marie,ON

I could have titled this "Possible Vega Gull" or "Vega-like Gull" but I opted not to hedge. This bird seems to meet all criteria for an adult Vega Gull. For those who aren't obsessed with Larusology you might be asking -What is a Vega Gull?

According to the AOU a Vega Gull  is Larus argentatus vegae the east Asian-western Alaska subspecies of the Herring Gull. Olsen and Larsson consider it a separate species L. vegae closer to Slaty-backed than Herring Gull. Ujihara the Japanese gull expert also considers it a species. Howell and Dunn describe the differing viewpoints and go on to say "American Herring Gull, European Herring Gull and Vega Gull are best treated as distinct species,".

Today at the landfill I noted a darkish mantled gull.

Adult Darkish Mantled Gull- Sault Ste. Marie

Although the mantle was clearly darker than the Herrings it clearly wasn't dark enough to be a Lesser Black-backed or darker gull. This immediately rules out Slaty-backed and Great Black-backed (GBBG)which this bird clearly isn't. The bright pink legs and mantle shade rules out Lesser Black-backed.

At first I was thinking Herring x Greater Black-backed hybrid. However on prolonged observation of the bird many things didn't seem to fit with that identification. First off the birds structure seemed very consistent with Herring Gull with no GBBG traits.

                 Adult Herring Gull                 Adult Vega Gull - Sault Ste. Marie

                      Adult Vega Gull           Adult Herring Gull  - Sault Ste. Marie

Overall in size the bird was similar to the surrounding Herring Gulls. It was larger than many but smaller than about 30% of the nearby Herring Gulls (observation at the time). The head shape was consistent with Herring Gull as was the bill size.

I noted what appeared to be a darkish eye.

Adult Vega Gull - Sault Ste. Marie

On very close inspection through the scope the eye was brownish yellow and the the orbital ring was distinctly reddish in colour. 

Adult Vega Gull - Sault Ste. Marie - close-up

If you go to your Sibley-Guide to Birds there is a very nice illustration of a adult Vega Gull on page 217 showing the orange-red orbital ring and the brownish yellow iris. The American Herring usually has a much paler iris and a yellowish-orange orbital ring.

Adult Herring Gull-head close-up

Many GBBG and LBBG hybrids could potentially have a reddish orbital ring as well. I really needed to get some open wing shots to look for the other differentiating features of Vega Gull- 1. a very broad white trailing edge 2. white tongue tips on P6-8. Both of these features are reminiscent of Slaty-backed Gull.

Well after about an hour I finally got a decent series of open wing shots.

Adult Vega Gull - Sault Ste. Marie

Note on the above bird the very wide white trailing edge as well as the white tongue tips on P6-8. (Tongues are the non black areas of the primaries sticking out into the black like a tongue.


Adult Vega Gull - Sault Ste. Marie -showing white tongue tips
Peter Adriaens pointed out that I had this primary incorrectly labelled P6. I had counted back from P10 and failed to note P7 is missing. I have corrected this on the current picture.This is actually even more supportive of Vega as most commonly a complete band is present across P5-although this is variable.-KZ

Adult Vega Gull - Sault Ste. Marie -showing white tongue tips

 The primary pattern on my bird is very similar to the Vega Gull wingtip pattern #2 shown in Olsen and Larrson pg. 28. None of the American Herring Gull patterns approach this especially the amount of white on the tongue-tip of P6.

I would like to thank Japanese gullmasters  Osao and Michiaki Ujihara for allowing me to use the following illustrative pictures from there excellent website. The following pictures were taken in late Oct. in Japan.



Adult Vega Gull -Japan-Oct.25/06-  Osao and Michiaki Ujihara

Note the similar stage of moult to my bird with mostly old primaries and missing coverts. According to Olsen and Larsson the outer primaries moult from late Nov. to Feb. Howell and Dunn confirm that Vega Gull under goes "a relatively late PB moult". In Ujihara's pictures of over 25 adult Vega Gulls on Oct. 25/06 all had retained some old primaries. In my bird P8-10 are old. Looking at hundreds of adult Herring Gulls today virtually none had retained old primaries and most had P9-10 almost completely grown in.

Adult Vega Gull-Japan -Oct.25/06-  Osao and Michiaki Ujihara

The above Vega Gull taken at a near identical time of year shows a near identical moult timing and wingtip pattern.




Adult Vega Gulls-Japan -Oct.25/06-  Osao and Michiaki Ujihara

The above photos show several Vega Gulls in late Oct all with retained old primaries and several with still all white heads like my bird. 

Chris Gibbins authored a study- "Identification of Adult Vega Gull: Field Observations from Japan". This was done in February so some observations such as head streaking could not be extrapolated to October birds. In most of the categories of observation well over 100 birds were studied. 


Comparing my bird to Gibbins results I found that- 83% of studied birds had a similar mantle colour to mine (20-30% saturated), 68% of the birds had similar bill markings to mine (red,no black), 70% had similar eye colour to mine (light to medium speckled), 68% had similar primary pattern (black to P5). 

The leg colour fell well within the 4 shades of pink illustrated (#678) but no percentages were given for the individual shades. He did say 93% of  L. vegae had dull pinky-flesh colored legs. The bright pink legs seen in breeding season are lost to a certain extent during the winter.


Adult Vega Gull  - Sault Ste. Marie showing "pinky-flersh coloured legs"


Adult Vega Gull-Japan -Oct.25/06-  Osao and Michiaki Ujihara

The above bird from Japan in late October shows similar coloured legs and bill as well as a nearly all white head and a similar stage of primary moult.

The variation of patterns on P10 were illustrated in Gibbins study and the 4th one illustrated was very similar to my bird. All in all this study reinforced that in all its main characteristics this bird fell well within the limits of the majority of Vega Gulls studied in Japan.

So to conclude I want to adress three questions from easiest to hardest.

1.Why isn't this just a regular American Herring Gull?

This is fairly easy- First the mantle shade is out of range of this species. The reddish orbital ring is also not seen in American Herring Gull. The primary pattern and very broad white trailing edge would also be quite atypical(but probably not impossible)for this species. The darkish eye is also atypical but a small percentage of Herring Gulls will have eyes darker than this.

Adult Vega Gull-Sault Ste. Marie -showing darker mantle and classic "Herring Gull" structure

2. Why isn't this a American Herring Gull X Lesser Black-backed Gull (LBBG) hybrid.

The main argument against this is the primary pattern and the very broad white trailing edge to the wings. This wouldn't be something you would expect given that the  adult LBBG usually has only a small white spot on P10, minimal white tips to the primaries and a relatively narrow white trailing edge. On some occasions they will have a small window on P9  shown on the bird pictured below. None of the multiple pictures of adults LBBG I reviewed in many sources had as much or more white on the wings. 

All the pictures of presumed Lesser Black-backed X Herring hybrids I have seen have had a very odd pinkish- yellow leg colour as well as a considerably darker mantle than would be typical for Vega. A good example can be seen in Photo #7 on Jean Iron's excellent website.


Adult Lesser Black-backed Gull showing maximum amount of white on wings

3. Why isn't this a Great Black-backed(GBBG) X Herring Gull hybrid?

This is clearly the most likely alternative identification. In fact initially in the field this was my presumption. However as I watched the bird I was increasingly stumped by its relatively light mantle much lighter than I would expect for this combination. Next I just could account for the total lack of any GBBG structural characteristics. No sign of the massive bill or odd "skinny looking" flat head. The size was that of a medium size Herring with none of the long -legged look of GBBG. 

Below are multiple pics of presumed GBB X Herring Gull hybrids that I will use to illustrate some points. All of these birds have been considered GBBG XHerring hybrids by multiple authorities

Second winter GBBG X Herring hybrid

Notice the large stout bill, the GBBG-like head and long legs. Although this picture doesn't portray its size well it was quite tall appearing and larger than most of the Herrings.

Second winter GBBG X Herring hybrid

Again a very stout bill with a flat angular head. Larger than most of the Herrings and quite tall appearing.

Third winter GBBG X Herring hybrid

Another tall bird with a very flat head and relatively stout bill. Notice the mantle shade quite a bit darker than my bird. The eye in this third winter bird is already lighter than. A very nice picture of an likely adult GBBG X Herring can be viewed at this site:


Adult Vega Gull-Sault Ste. Marie-showing rounded head and relatively average "Herring Gull" type beak

The above bird shows no trace of GBBG structure that I can detect. This was obvious in the field were it fit in nicely with the surrounding Herrings many of which were bulkier and larger than it. 



Adult Great Black-backed Gull showing flat angular head and massive bill

The next reason this bird is not a GBBG X Herring hybrid is its primary and secondary flight feather patterns. Both the Herring and Great Black-backed Gulls have medium sized white trailing edges to the secondaries. My bird as is typical of Vega has a very wide trailing edge reminiscent or maybe even wider than in a Slaty-backed.


Adult Great Black-backed Gull showing medium width trailing white wing-edge and typical primary pattern


Adult Herring Gull showing medium width trailing white wing-edge and typical primary pattern


Third winter Herring Gull   Third winter GBBG X Herring hybrid
Both showing medium width trailing white wing-edge.

Below I will show pictures of a variety of adult Vega Gulls to illustrate the very broad white trailing edge to the wing along with the typical primary pattern usually with a large window on P10 and P9 and white tongue tips.



Adult Vega Gull, May/09 Gambell,Alaska




Adult Vega Gulls-Japan - Osao and Michiaki Ujihara

Compare the Vega Gulls from Japan and Alaska to my Sault Ste. Marie bird.


Adult Vega Gull- Sault Ste. Marie-showing very broad trailing white wing-edge as well as white-tongue tips to primaries

My final point is perhaps the most important of all and to me makes the identification of this bird as a Vega Gull secure. My bird is in relatively early prebasic molt with three retained old primaries per wing.
This is very typical of Vega Gull at this date. Ujihara noted that of 40 Vega Gulls he examined on Oct.25th,2006 all but 2 had retained primaries. Many still had retained primaries into late December.

Of the hundreds of adult American Herring Gulls I examined closely over the last two days I could not find a single bird with a retained old primary. Although moult is clearly a variable thing it would appear that Vega Gull is fairly unique in its late prebasic moult. Great Black-backed Gull typically is at this stage of moult in late August-early Sept. I have never seen a GBBG with retained primaries in late October.


Adult GBBG in active prebasic moult-Sept 1/2005 Virginia Beach

Although Vega Gull is clearly a very rare find in the east it would not seem any less likely than Slaty-backed Gull which is a regular visitor to western Lake Superior over the last five years. Michael Brothers had a very nicely documented adult Vega Gull at Daytona Shores last winter. Unfortunately young birds are a very challenging identification and most of these birds are likely never identified.

This bird has Herring Gull like size and structure with a darker mantle,  a reddish orbital ring, a very broad white trailing edge to the wing and a typical Vega Gull primary pattern. The eye clour, leg colour and bill pattern are all consistent with the majority of Vega Gulls studied by Chris Gibbins in Japan. To boot it is in active prebasic moult with three retained primaries a good 2 months after all the other candidate large gulls and hybrids should have been at this stage. I think this is sufficient evidence to identify this bird as an adult Vega Gull.

I am hoping this bird sticks around so I can document it in full winter plumage. I did search for it today without luck but it is likely still around and I will be keeping a close eye out.

Comments on this bird would be appreciated.
See ya

Kirk
zufelt_k@shaw.ca
















6 comments:

  1. Very nicely documented Kirk! A lot of patience to get the all important flight shots. If I saw this bird in East Asia, I would have no hesitation in calling them a Vega Gull. A remarkable find!

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  2. Amazing find and wonderfully documented. Well done!

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  3. Looks good to me! Note that there is an accepted Vega adult from Florida, two winters ago. I have found many Vega youngsters in California, the adults are much more problematic to identify here with the huge range of back colors in West Coast gulls and hybrids. I have some candidates though. Alvaro.

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  4. Great comparison photos. Thanks for the informative write up.

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  5. i would apprecate help in identifying a gull. i have a photo of a bird with a black beak, and legs, black tail feathers and grey wings with white tips. the bird looks to have black rather than yellow eyes as well. there is some mottling of color on its head and belly. is this a juvenile? any idea what kind. it is from daytona, florida.

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  6. Great bird, and very well documented. I agree with your ID of Vega. One correction, I believe, which is that Lesser Black-backed Gull has a similarly late molt, so a Herring x LBBG hybrid could also have a late molt like this bird.

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