Monday 5 November 2012

'Split me, lump me, any way you want me... long as you tick me, that's alright' (with apologies to Amen Corner or whoever wrote that lyric first). Thus can be summarised the lengthy discussion on a local internet birding forum about the identity of a Siberian Stonechat recently on Portland. After the initial ID as Siberian, attention focused on the bird's relatively warm colouration. The possibility of it being of the eastern Asian sub-species stejnegeri was raised, a prospect supported by the presence of other birds from the far east in Dorset at the time.

This shot just about shows the unstreaked rump of Siberian Stonechat
In terms of species status, stejnegeri is currently regarded as a sub-species of Siberian Stonechat (maurus) but a potential future 'split' from it. Or future 'lump' with Stonechat, depending on how you look at it, or how much time you want to give it before the warring factions of boffins who decide these things change their minds again about what constitutes a species. Siberian Stonechat has itself only recently been split by the BOU from Stonechat, a momentous decision about which all Stonechats, Siberian or otherwise, did not give two shakes of their streaked/unstreaked rumps.

Note the hint of an eyebrow in this shot
So subtle are the differences between maurus and stejnegeri, however, that the identity of the Portland bird could not be confirmed even after it was caught and had its inside leg measured - the bill width was frustratingly inconclusive, apparently. After the incredible record of a Sakhalin/Pale-legged Leaf Warbler in a Portland garden a few days earlier, this was presumably the second time in a week that the redoubtable Portland Bird Observatory Warden Martin Cade was left scratching his head with an identification challenge, and I can't imagine that happens very often. Fortunately in the case of the Stonechat modern science came to the rescue and a DNA sample taken (from faeces or a feather, not sure which) has since proved it to indeed be stejnegeri.

Although I had limited time, the bird came reasonably close...
...but never gave me a clear opportunity to photograph the unstreaked rump in full.

All this post-hoc-sub-species-specific-identification-by-DNA-analysis-of-potential-future-armchair-ticks is a bit confusing for the humble field birder. Though I suppose it does at least level the playing field between us duffers and proper birders when only the folks in white coats who are happy to poke around in bird turds know what we are all gawping at. Fortunately, I managed a brief gawp last Friday morning between packing cases for a week on the Isles of Scilly, more on which later.

A typical pose...

..and an amazing record given the likely origin of this bird

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