Saturday 3 December 2016

Taimyr Gull: adults and sub-adults

I recently posted on a couple of 1CY Taimyr Gulls in Mie seen on the 26th of November, I got a few images of adults on the same day too and I'd planned to post them much sooner but birding got between my intention and getting round to it.

The very first gull I came across that day was a Taimyr, I popped my head over the bank to see in which direction along the beach gulls were loafing and there it was right in front of me.

The centre of attention with egrets on one side and me on the other. A typical Taimyr in terms of saddle shade, bare parts colouration (legs often have a pinker element in winter) and moult.

The same bird on the beach, three retained primaries is typical at this time, the vast majority of Vega are more advanced. Taimyr almost always has a gap in the inner greater coverts which isn't visible in this shot but is in the previous image, Vega never does.  The red in the bill normally reaches the cutting edge, as it does on the left side visible in the previous image though it falls short in this shot.

The same bird again, now with a Vega for comparison. Note the number of new primaries on the Vega, the saddle is clearly paler but this isn't always the case as Vega is very variable. Though the red in the gonys of this Taimyr is more restricted than most it is nevertheless far more prominent than that of the Vega, even at this distance it forms an obvious dark spot.

A different bird, the same features. Extensive red in the gonys, darker saddle, three retained outer primaries and a chunk of missing inner greater coverts. The legs are yellower on this individual.

The same bird. Head markings are variable on both Taimyr and Vega but on average Taimyr is far more finely marked.

Yet another Taimyr and again the appearance is spot-on and quite different to Vega. Again three outer primaries are retained but on this bird p5 is the longest, p6 is some way short yet. It's obvious in this shot that it isn't just the greater coverts that are actively in moult and that the old median and lesser coverts look ragged, Vega has completed coverts moult by this time and they look very 'smooth'.

Compared to this Vega the retained primaries give it an attenuated appearance, this can be a give-away at very long distance at this time of year. The coverts are tatty by comparison, the bill has more extensive red in the gonys and the saddle is clearly darker.

The same bird with a different Vega, notice how the variation in Vega saddle colour can affect the perception of Taimyr saddle colour.

The same bird in flight, white patches and spots are usually visible on the Taimyr wing at this time of year caused by dropped feathers revealing the bases of the tract below. White patches are often far more conspicuous than on this individual.

A bird with heavier than usual head and more particularly hind neck / breast markings. I used to think red extending onto the upper mandible was a feature of Taimyr but I now realise this is the exception rather than the rule. 

The following bird might be termed a sub-adult but I don't know with certainty how old it is, if I had to guess I'd say 3CY but I don't see many birds between juv / first winter and adult. It has almost completed primary moult (p10 is just shy of full grown) and all coverts and scapulars have a brownish cast not present on adults.

Unworn A-spots and p10 not quite fully grown indicating it is near completion of primary moult well ahead of adults.

I didn't get a shot of the spread wing but at least it's possible to see the primary coverts show extensive black.

I took the following image a few years ago on 8 December, two birds which I believe are 2CY and 3CY respectively. This is the best indication I have as to how these gulls develop and it is why I'd hazard this bird is a 3CY.

Two gulls in Osaka a few years ago. I presume these are 3CY (left) and 2CY.

From what can be seen of the wing I think the older bird looks essentially identical to the recent bird.

For completeness here are a small selection of Vega images from the same day showing how their primary moult is progressing.

This was the only full-winged Vega that day though there were a few a week later and far more as I write (4 Dec)

This represents the typical state of primary moult on that date.

There were a few Vega with a retained p10, this the only one I noticed still with p9. It also has a longer new feather projection than I'd expect from a Taimyr.

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