Wednesday 30 November 2016

Taimyr Gulls: a couple of 1CY birds

I was late off the mark gulling this year thanks to Wood Warbler and Black Bittern earlier in the month (no complaints on that score) but I was still hopeful of finding juvenile Taimyr Gull either near the mouth of the Yamatogawa in Osaka or on the beach in Tsu.

I tend to drive to Tsu nowadays because although it takes an hour longer it's still preferable to the the five different trains I'd have to take (each way), topped off by a 30-minute walk from the last station, to a good spot on the river. Carrying a load of gear on packed commuter trains has never been in my top one hundred fun things to do on a day off. Another big advantage Tsu has over the Yamatogawa is that the gulls are reasonably approachable on the beach whereas the gulls on the river are on mid-stream shoals, I say mid-stream but, as you'd expect, they always seem to settle closer to the far bank.

I spent the last two or three hours of daylight on the beach north of Tsu city on the 18th, after first spending the earlier part of the day birding further south. The only 1CY gulls I saw all had second generation mantle and some scapulars in place. My visit to Mie on the 26th was more gull orientated, after a far more cursory check of some estuaries and areas of fields I got to the beach by early afternoon and managed to find one bird still in juvenile plumage.

One of the birds on the 18th was a really big brute of a Taimyr. I come across a few huge adults and used to wonder at the enormous size difference (and structure, the big birds tend to look proportionately shorter-winged) between the largest and smallest of them. But when I see  such a large individual amongst a group of first winter (1CY / 2CY) Taimyr I feel reassured they really are just as variable as any other large gull taxon. Below are a few images of the big bird...

Mantle and most scapulars are now second generation, just a few lower scaps still juvenile. 

Perhaps size illusion coming into play here, nevertheless it is very much at the larger end of the Taimyr scale.

A clearer view of retained lower row scapulars. Apart from size this is an bog-standard Taimyr right down to the 'Dusky Thrush' breast-side and flank spots.

Strikingly dark outer greater coverts, neatly marked axilliaries (and underwing coverts) are typical. Likewise the white ground to vent, undertail and uppertail coverts with strongly contrasting spots. Some birds seem to have more continuously marked, rather barred and Vega-like upper- and undertail coverts.

The coverts bar is often more apparent with distance. This bird has darker inner primaries than most.

Typical tail pattern, Vega tends to have more extensive black in the outer feathers.

The primary window is usually more conspicuous than this.

Depending on light conditions these immatures can look browner or greyer but in fact this isn't merely light-related, there clearly are browner and greyer types. The following gull (26th) is a nice example of a greyer bird, though they do come even more strikingly 'black and white' than this.

The juvenile plumage juxtaposed with the bright pink (and extensive) base to the lower mandible, equally bright spot in the gape of the upper and more diffuse loop extending from the base around the nostril is eye-catching.

This gull has a strong fuscus feel to it. It's not only the upperparts that lean that way, the lightly marked centre of the breast and belly, almost clean white on the lower belly extending through the undertail coverts which highlights the strongly marked side feathers. Vega tends to be duller and less contrasting frequently barred across the full width of the undertail coverts.

From behind this is a very uniformly dark gull, quite blackish even though the strong light usually brings out the brown tints in these birds.

The rear flank feathers are noticeably dark and form a terminal flank crescent behind each leg and emphasise the clear white lower belly (not visible here).

When the wings are slightly spread the visible inner primaries show a clear contrast between the darker grey of most of the feather length and the very pale sub-terminal area on the inner web just behind the black 'diamond tip'; effectively a short white trailing edge on this kind of view. Vega would show less contrast between tips and bases, thus the 'diamond tip' would look more isolated. 

The primary window looks typical on this gull, more conspicuous than on the previous large gull but nevertheless far duller than that of Vega.

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