A couple of weeks ago, local birder Matt Knott kindly let me know of a Siberian Chiffchaff which had been seen on the Otter by a visiting birder. It is only in the last couple of days that I have found time to have a proper look and it would appear there are now two birds associating with at least 2 "collybita Chiffchaff"
I am certainly no expert when it comes to Chiffchaffs and there is an awful lot of literature on them! So in basic terms, chiffchaffs wintering in Britain are most likely to originate from 3 areas:
Western and Central Europe: Phylloscopus collybita
Finland and Scandinavia: Phylloscopus collybita abietinus
The Urals and further East: Phylloscopus collybita tristis
I have found a Siberian Chiffchaff on the patch previously (during the hard winter weather of January 2010 and very close to where this year's birds are frequenting - see HERE) However, since then, thoughts on plumage criteria for assessing Siberian Chiffchaff have changed somewhat.
Following DNA analysis, a paper was published in Dutch Birding in 2012 covering DNA research on 41 Chiffchaffs trapped in the Netherlands in the autumns of 2009-11. Most of these birds were identified in the hand as "non-collybita" birds i.e. tristis (from the Urals and further East) or abietinus (from Northern Europe Fenno-Scandia) using a suite of plumage characteristics very similar to those published by BBRC as a guide to help county submissions of potential tristis records. The conclusion from the DNA, crucially showed all birds identified using such plumage charcteristics and thought to be abietinus; were actually proven to be tristis. Therefore suggesting that any non-collybita Chiffchaffs wintering in the UK are more likely to be tristis and that abietinus is actually likely to be very rare bird in the UK.
Perhaps unsurprisingly, it now seems that basing id on plumage alone is not good enough and there is much variation, with some tristis having more green and yellow tones than previously thought possible.
SO, a cold toned looking chiffchaff with obvious brown tones to the upperparts, particularly around the ear coverts and supercilium and quite clean pale undertail coverts is certainly worthy of a closer look. The all important single "peep" call would still appear to be the clincher though. To my ear, the call is quite mournfull and vaguely similar to Bullfinch.
Both the birds below responded very well to the call of Siberian Chiffchaff call and one bird even began wing quivering in response to Siberian Chiffchaff song.Very interesting to see just how different birds can look in different light though! See photos below.
Chiffchaffs are always interesting, especially in winter as you never quite know what else may be lurking with them, like Yellow-browed Warbler for example. Anyway, certainly a learning curve and the more experience gained with such birds, the better!
|A very green looking and typical "hweeet" calling collybita
|Siberian Chiffchaff - cold toned, broad buffy super and warm brown ear coverts and mournful single "peep" call -though bill not looking that dark...
|Same bird as above in different light! Very different looking bird in sunlight.
|Same bird as above two images - almost looking like a Bonelli's Warbler with those brightly edged tertials and rectrices!
|Bird 2 - Subtle wing bar present on greater coverts and overall cold grey brown tones. V black legs
|Bird 2 - other side. Again showing subtle wing bar
|Cetti's Warbler - also frequenting the same area