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Saturday, 1 November 2014

Do they know it's tristris time at all... ?

There's been a rash of sightings of 'tristris', or Siberian Chiffchaffs in the country these past days, and Kerry has seen at least 5 of these, 4 on headlands, but one (see below) in a garden near Tralee in the company of a Yellow-browed Warbler.

A pale Chiffchaff with a wing bar in autumn is not always a 'Siberian', as there is a wide range of variation across Scandinavia and Russia, with a tendency towards paler birds the further east you go. A 'classic' Siberian Chiffchaff is always pale, and has a lack of yellow tones to the underparts, a lack of rich green on the mantle, and (usually) fairly bright green fringes to the wing and tail feathers. The pale wing bar is usually apparent though not prominent, but is sometimes very faint or absent in some.

The final box to be ticked, for anything but the most clear cut 'Sibe', is the call – a loud, piping call with just a hint of down-slurring at the end, very different from the more typical up-slurred, 'hoo-eet' Chiffchaff call.

Trouble is, there are other races of Chiffchaffs from eastern regions which have some or all of those suite of plumage characters. Of the 7-8 Chiffchaffs present in the Finian's Bay/Bolus Head area yesterday, there was much variation, from at least two showing all the above characters of Siberian Chiffchaff, to 3 others showing most, but not all characters. The borderline between classic Siberian Chiffchaff and an eastern pretender can be a slim one, especially if the bird doesn't call.

'Siberian' Chiffchaff, Bolus Head, 31st October 2014 (Michael O'Clery).
Very different to our own typical Chiffchaffs in autumn which are often suffused with rich yellow, buff and green tones. This individual did occasionally call, a piping, slightly down-slurred, 'hleeep'. Note the lack of yellow anywhere on the underparts (except the area around the 'bend' of the folded wing), 'frosty' edges to the tertials and greenish tinge to the edges of the secondaries.

Chiffchaff, Bolus Head, 13th October 2014 (Michael O'Clery).
Although showing a fairly obvious short wing bar, the yellow and green tones mean it is not a Siberian, but perhaps has at least some eastern genes.

Chiffchaff, Bolus Head, October 2014 (Michael O'Clery).
A typical autumn Chiffchaff, olive above and suffused throughout with yellow and buff.

'Siberian' Chiffchaff, Finian's Bay, 31st October 2014 (Michael O'Clery).
This bird seems to show all the pertinent features of Siberian Chiffchaff but, rather unhelpfully, didn't call for quite a while. Have a close look at the photo below of the same individual (you can click on the image for a close-up). There seems to be a little patch of yellow or buff in the centre of the breast and perhaps a hint of yellow in the supercilium?  Does this rule it out as a Siberian Chiffchaff? It might have, except it finally gave a Siberian Chiffchaff-type call.

'Siberian' Chiffchaff, Finian's Bay, 31st October 2014 (Michael O'Clery).

Interestingly, the eastern type Chiffchaffs, including the two Siberians, spent a lot of time feeding on the ground, in one case in an open grassy field, in another, hopping and flitting through sedge tussocks. Our more typical autumn Chiffchaffs are rarely seen away from bushes and trees, though of course, on migration, birds must occasionally feed wherever they can.

'Siberian' Chiffchaff, Kerries, Tralee, 31st October 2014 (David O'Connor).
This bird shared the garden with a Yellow-browed Warbler.

'Siberian' Chiffchaff, Kerries, Tralee, 31st October 2014 (David O'Connor).