Saturday 18 March 2017

A second Thayer's Gull in Mie (or so I thought)... but no Bonaparte's

I was gulling in Mie last week and some birders asked my opinion about a Bonaparte's Gull they had found. It was difficult to judge a single back of the camera image, it looked promising but unfortunately the gull had already flown off. However it was seen again during the week and its identity confirmed so I've just got back from two fruitless days looking for it. I was told it probably left with a large transient flock of Black-headed Gulls. This flock contained a number of blue-banded birds one of which I had seen the previous week.

The closest I came to the Bonaparte's? A blue-banded Black-headed Gull which was probably at least on nodding terms with the American.

Fruitless as far as the Bonaparte's was concerned but I did get great views of anadult Thayer's Gull. It's known as Mi-chan apparently, the 'Mi' being the same kanji as in Mie. I got a very brief flight view as it dropped into the middle of a loafing flock and this head shot is the best I could manage.

I was told by a local guller who looked at this image that this bird is Mi-chan, now into her 10th winter at this site! Another Thayer's that also used to winter regularly no longer does so.

This is where my claim of a second Thayer's gets slightly tricky. I'm no expert on the local gull population in Mie. Could it be the bird I saw later was also Mi-chan despite believing it looked different? Just I was getting better views?

Well now with hindsight, and importantly further views of Mi-chan, I can answer that question and in fact I was mistaken, I did only see one Thayer's rather than the two I originally thought. These following images are of the same bird.

I was warned by my informant that there is a hybrid resembling a Thayer's in the area (as well as the usual thayeri-type Vegas) and that care is needed. Presumably there are a number of mistaken IDs. I'm aware of the pitfalls, which doesn't mean I'm proficient at avoiding them of course. This next gull does look more of a pitfall to me. Perhaps it's 'the hybrid' I was warned of, though I'm uncertain what kind of hybrid it could be. Perhaps it's just a Vega with an extreme wing-tip pattern, I do see a few Vega with thayeri-type outer primaries though usually not such a good match as this, but other than the pattern of the outer six primaries there's nothing about this gull that looks out of the ordinary for Vega.

It looked pretty good for a Thayer's coming in like this but that's as good as it got.

Once on the ground things soon began to fall apart. It's just a little too big and heavy, those legs are a little long and distinctly pale pink, that bill seems a tad too robust and the saddle a shade or two too darker than I'd like.

Perhaps the eye is just a little too pale and the eye ring not purple enough. There's an aggregation of too many not-quite-rights. And isn't the black of the outer primaries in the following two images just a little too black...

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