Originally posted to Surfbirds by Steve Preddy
There's a fascinating paper in the current issue of BB by Alan Dean and Lars Svensson, dealing with Siberian Chiffchaffs. Lars and Alan are commendably cautious in the way they word their conclusions - quite rightly so, as what they have to say is quite radically different from "accepted wisdom". However, if one follows their arguments through (with a bit of extrapolation/oversimplification) I think you get the something resembling the following.
1. Much of what's been written on Sibe Chiffchaff over the last few years is rubbish. As a result, if you think you've seen Sibe Chiffchaff in Britain, you almost certainly haven't, even if you heard it call and it didn't sound like a Common Chiffchaff - this just means you haven't been listening to Common Chiffchaffs carefully enough, as they have lots of calls, not just 'hweet'
2. Siberian Chiffchaffs are brown above and washed buff below, and not at all pale - when we say brown, they're not in Dusky Warbler's league but they're heading that way - forget the idea that they're "grey & white" - that's nonsense
3. There might be a discernible western population of Sibe Chiffchaffs which can be separated as "fulvescens", but there probably isn't and the idea that there is might just result from some overactive imaginations - all that's probably going on is a greater tendency towards some yellow in some parts of the plumage in the west of the range - apart from that the birds here are still essentially identical in appearance to tristis ... repeat - they're not "grey-and-white"
4. Grey & white chiffchaffs like those seen in Britain in many recent winters are just eastern abietinus Common Chiffchaffs ... follow the collybita-abietinus cline east, and this is what you get; the difference between these birds, which in some quarters have been called - incorrectly - "classic tristis", and "not so classic" birds, has no real significance - they're all just flavours of abietinus, or possibly hybrids. They're NOT tristis!
5. Whilst there is clearly a well-documented collybita-abietinus cline, there isn't anything like as much existing between abietinus and tristis; it's likely there's some hybridisation going on, but it could be just as unimpressive & insignificant as that between Common & Iberian Chiffchaffs.
6. Calls? ... Common Chiffchaff has a variety of calls, and there's a bit of geographic variation going on too; grey-and-white chiffchaffs, if they call oddly, are just reflecting that. Some of these calls can be transcribed in the same way as that of tristis, and so could easily fool observers who don't have experience of tristis into thinking that tristis is what they've heard ... WRONG!!!
7. As for grey-and-white chiffchaffs with "different-sounding" songs ... probably they're just "mixed singers" ... either hybrids, or birds of the race abietinus from near to the hybrid zone that have learnt the wrong song.
8. So, to recap, both Common Chiffchaffs and Siberian Chiffchaffs vary individually and geographically, Common Chiffchaff more so, to the extent that out-of-context pale eastern birds can give the impression that they're a different species from dingy western birds - but they're not. Common & "real" Siberian Chiffchaffs do however look different in all plumages, and have totally different songs ... now then, what's the genus we're dealing with here again? ... and when we get such striking differences in song between two different forms in this particular genus, especially when correlated with fairly sizeable DNA differences, what does that mean? Correct - we do have two different species, but their respective appearance is quite different from the mental images which most British birders currently have. Furthermore, most birders have only seen one of them in Britain - time to get the tippex out !!
There's a fascinating paper in the current issue of BB by Alan Dean and Lars Svensson, dealing with Siberian Chiffchaffs. Lars and Alan are commendably cautious in the way they word their conclusions - quite rightly so, as what they have to say is quite radically different from "accepted wisdom". However, if one follows their arguments through (with a bit of extrapolation/oversimplification) I think you get the something resembling the following.
1. Much of what's been written on Sibe Chiffchaff over the last few years is rubbish. As a result, if you think you've seen Sibe Chiffchaff in Britain, you almost certainly haven't, even if you heard it call and it didn't sound like a Common Chiffchaff - this just means you haven't been listening to Common Chiffchaffs carefully enough, as they have lots of calls, not just 'hweet'
2. Siberian Chiffchaffs are brown above and washed buff below, and not at all pale - when we say brown, they're not in Dusky Warbler's league but they're heading that way - forget the idea that they're "grey & white" - that's nonsense
3. There might be a discernible western population of Sibe Chiffchaffs which can be separated as "fulvescens", but there probably isn't and the idea that there is might just result from some overactive imaginations - all that's probably going on is a greater tendency towards some yellow in some parts of the plumage in the west of the range - apart from that the birds here are still essentially identical in appearance to tristis ... repeat - they're not "grey-and-white"
4. Grey & white chiffchaffs like those seen in Britain in many recent winters are just eastern abietinus Common Chiffchaffs ... follow the collybita-abietinus cline east, and this is what you get; the difference between these birds, which in some quarters have been called - incorrectly - "classic tristis", and "not so classic" birds, has no real significance - they're all just flavours of abietinus, or possibly hybrids. They're NOT tristis!
5. Whilst there is clearly a well-documented collybita-abietinus cline, there isn't anything like as much existing between abietinus and tristis; it's likely there's some hybridisation going on, but it could be just as unimpressive & insignificant as that between Common & Iberian Chiffchaffs.
6. Calls? ... Common Chiffchaff has a variety of calls, and there's a bit of geographic variation going on too; grey-and-white chiffchaffs, if they call oddly, are just reflecting that. Some of these calls can be transcribed in the same way as that of tristis, and so could easily fool observers who don't have experience of tristis into thinking that tristis is what they've heard ... WRONG!!!
7. As for grey-and-white chiffchaffs with "different-sounding" songs ... probably they're just "mixed singers" ... either hybrids, or birds of the race abietinus from near to the hybrid zone that have learnt the wrong song.
8. So, to recap, both Common Chiffchaffs and Siberian Chiffchaffs vary individually and geographically, Common Chiffchaff more so, to the extent that out-of-context pale eastern birds can give the impression that they're a different species from dingy western birds - but they're not. Common & "real" Siberian Chiffchaffs do however look different in all plumages, and have totally different songs ... now then, what's the genus we're dealing with here again? ... and when we get such striking differences in song between two different forms in this particular genus, especially when correlated with fairly sizeable DNA differences, what does that mean? Correct - we do have two different species, but their respective appearance is quite different from the mental images which most British birders currently have. Furthermore, most birders have only seen one of them in Britain - time to get the tippex out !!
