Call and Plumage Variation
A quick post by way of advance notice and apology. I have been working on a piece about Siberian and Common Chiffchaffs. I posted it ‘privately’ to facilitate excellent input from others, expecting to publish soon after. Then I got distracted.
Even greater variation in calls
In the course of reviewing material I revisited a fascinating Siberian-type Chiffchaff recording in Shetland in October 2010. This bird gave an amazing range of calls from rather typical tristis -like ‘peep’ to ‘swee-oo’ and ‘hweet’ calls just like western Common Chiffchaffs (nominate collybita). It looked like a tristis. Turns out I am not the only one to have recorded such a confusing (and enlightening) range of calls emanating from the same bird.
presumed Siberian Chiffchaff, Halligarth, Unst, Shetland, October 2010. The range of calls uttered by this bird engendered new questions and new information, alongside other call variants recorded in both Common and Siberian Chiffchaffs.
Even greater variation in plumage
Meanwhile a paper, published in Dutch Birding this week (vol 34 -2012- no.6) brings further revelation and may answer the questions I have had about birds like this:
possible Siberian Chiffchaff, Valyie, Unst, Shetland, October 2012. This elusive bird was a most striking Chiffchaff. Very grey above, with big flaring supercilium, and bright lemon yellow patch above the eye. I mooted that, had it called, it would sound ‘Siberian’ but it never obliged.
The just-out Dutch Birding paper covers DNA research on 41 Chiffchaffs trapped in the Netherlands in autumns of 2009-11. Most of these 41 were birds identified in the hand as not typical nominate collybita– some being identified as tristis and others as abietinus.
Critically all birds identified as abietinus (using the kind of characters most of us might similarly apply) were found to be tristis based on DNA (as well as all the obvious tristis). This will dramatically change the understanding of Siberian Chiffchaff occurrence in the Netherlands.
Such new understandings of call and plumage variation will surely catalyse fresh debate on the kinds of characters which can be used to identity Siberian Chiffchaffs in W. Europe. Keeps us humble and learning.
Lots more to come including full range of sound files, sonagrams and photos in forthcoming post, once I make sufficient sense of it myself!