Later in the afternoon, on a beach where the gulls can be approached more closely, I was able to get better shots of gulls. The following images show a sub-adult Taimyr with an almost a complete black ring around the bill. Originally it was with a small group of gulls, Vega and a couple of first winter Taimyr and I later relocated it in flock of mainly Vega further down the beach.
As with the other local gulls, Vega and Slaty-backed, there's a fair amount of variation within saddle colour. By this I don't mean there's a huge difference in saddle colour but that (except for extreme individuals) numbers are evenly distributed along the range of variation. It's difficult to put your finger on what a "classic" saddle shade should be. As can be seen below this bird is slightly darker than the average Vega.
A flock of mainly Vega Gulls. The sub-adult Taimyr is third from the right, behind it is a Common Gull L.c.kamtschatschensis and to its left an adult Taimyr.
No doubt it's the hope of every guller to find a so called "classic" if lucky enough to come across a potentially rare gull, well it's certainly mine anyway, and in Japan Vega as by far the most common Herring-type gull is the yardstick to measure the scarce or downright rare against. When it comes to the scarce taxa the slow drip of information means the range of acceptable appearance only slowly reveals itself. Where and what are the boundaries? How many 'good' birds might have to be discarded, how many extreme local birds might blur the boundaries you are looking for? How many "classics" are there in any given population. Oh dear, the usual questions.
By February a small number of Vega have become largely white-headed and lost their prominent grey shawl but most are still streaked to a greater or lesser extent. Some like the the two gulls below are doing their best to keep up appearances and match field guide standards. But many become slightly more difficult to identify and there are always some confusing individuals I'd prefer to forget about if it isn't possible to see them really well.
The following gull is a good example of the latter. It stood out because of its strikingly white-headed appearance. Earlier in the winter anything this clean would immediately suggest Mongolian but more caution is needed by this time. Mongolians from different populations may differ but none I've ever encountered have this wing pattern. The obvious red on the upper mandible definitely isn't something I'd expect to see in Vega, even in breeding condition. It is a little darker-saddled than the Vegas present but the wing tip isn't good for Taimyr either. I wish the bird had hung around but after a couple of minutes it flew off and I didn't relocate it then or last weekend when I visited the same spot. This combination of features is interesting but it'll just have to remain unidentified.
With adult Vega and first winter Taimyr. The red on the gonys is very extensive, even for Vega in breeding condition.
The extent of red on the bill and rather dark saddle is an odd combination except for Taimyr which this bird doesn't seem to be judging by the wing pattern.
The short p10 on the right wing is peculiar. I've seen online images of Mongolian from their breeding range with a mirror breaking through to the tip but it isn't a feature I'm used to seeing on birds here. Perhaps it originates from a different population? Also birds I see here have more extensive black in the outer primaries, both inwards as sub-terminal bands and towards the bases of the outer feathers.
I previously posted on adult taimyrensis type gulls here but focused more on distinctly darker saddled individuals which may actually be misleading.