Saturday, 11 January 2020

Siberian Chiffchaff - A Conclusion

I think I am just about done with my Siberian Chiffchaff reading. It has embraced a wide spectrum of material and is slowly eroding my will to live. However, I would like to impart at least the essence of this journey via NQS, and have decided to begin at the end. So, here is the bottom line...
  • If it looks like a tristis, sounds like a tristis, and has the DNA of a tristis, it's a tristis. Sorted.
So just get out there, find yourself a cheery little 'pale and interesting' Chiff, take a description, record its call/song, and pop that dropped feather/fresh poo into an envelope addressed to Prof Martin Collinson at Aberdeen University.

Yeah, right...

Or, you could do what I've done. Read enough bumph to convince yourself that any pale and interesting Chiffies you come across are pretty much guaranteed to be tristis. Forget the DNA test. Enough people have already been down that road to persuade me that birds which look like a tristis will return a DNA test result saying exactly that. If you hear it call, great. A nice, flat, sad 'eeep' or 'iiihp' (at approximately 4.5 kHz, for those of you with perfect pitch) will do nicely. If you don't? Never mind. Almost always, if it looks like one, it will call like one.

Having said that, there are a couple of ways you could get yourself in a pickle. The first is by worrying unduly about the F-word...

Fulvescens
This word crops up everywhere, and generally is used to describe birds which differ in appearance from so-called 'classic' tristis (which show no yellow apart from at wing bend/underwing, and no olive in crown or mantle) by having some limited yellow/olive in their plumage. Like these birds...

Top two: one of the Colyton WTW birds
Bottom two: Chideock WRC bird (RH photo courtesy Richard Phillips)

Note yellowy-green on wing edges, tail, etc. Frequently I have seen 'fulvescens type' used to describe a Sibe Chiff like this. Unfortunately, when bandied about in birder chat the term seems usually to be applied in a disparaging way, inferring that the bird either is not a Sibe Chiff at all, or is some kind of tenth-rate one. However, I have read enough to be very confident that the vast majority (if not all) birds that look like those two above will be absolutely stuffed to the gills with tristis DNA. That's good enough for me. They are tristis. Probably from the W end of the range, but still tristis.

The next two beauties are seemingly not fulvescens type birds...

Bottom left: Kilmington WTW
All others: Colyton WTW bird #2

These two birds are closer to 'classic' tristis than the top two. But, for me, all four are still tristis. The three pics of Colyton WTW bird #2 illustrate how cautious we need to be when assessing colour tones just from photos. They're all slightly different, and prove to me that a description based on just an image is not trustworthy.



The other way you might get your underwear knotted is by worrying unduly about the dreaded...

Contact Zone
This is the vast mixed playground where abietinus and tristis overlap, and little chiffing hybrids are made. Drilling down into the genetic nitty-gritty of birds in this zone is the proverbial can of worms. Even well to the E of this zone, on the West Siberian Plain, some of your pukka tristis are quite likely to carry tiny, tiny bits of abietinus baggage. It's a mess, frankly. And the only way I am able to deal with it from an everyday birding perspective is to leave the lid on.

The obvious question is, surely at least some of our pale and interesting Chiffs must be dodgy hybrid/backcross beasts? The logical answer has to be yes. And what about abietinus? Well, maybe...

But...

For a start, as far as I can discover, very few abietinus Chiffies have been proven by DNA in Great Britain and Ireland. Something like nine in total, as of a couple of years ago. And, importantly, abietinus doesn't appear to look like a Sibe Chiff. As far as mucky hybrid things are concerned, well, it must theoretically be possible that your putative Sibe Chiff will look like one on the outside, but be a genetic smorgasbord on the inside, but the rule seems to be that Sibe Chiff candidates - including so-called 'fulvescens' types - give tristis DNA results when tested.


All the above is admittedly a very simplistic treatment of what is clearly a complex issue. That's deliberate. I do not wish to make this the dullest NQS post ever by quoting figures and citing various 'authorities' left, right and centre. What I want to do - and what I'd love any reader to be able to do - is be confident that the pale and interesting Chiff which has just crossed our path can be indentified without a massive palaver. My own treatment of the little cuties will be as follows...
  • Is its plumage somewhere on the spectrum of tristis - including so-called 'fulvescens'? Yes? Have it.
My research into this has convinced me that at least 99% of the time this will be a safe ID, and for a bird that is not mega-rare that's good enough for me. If it calls, great. But I've spent quite a lot of time with five different birds this winter, and I've heard just one of them call, on one occasion, three times. As far as I'm concerned, it doesn't need to call.

But wait a minute! My county needs the call, or song, for a tristis to be acceptable.

This is a fair point. Sibe Chiff is no longer a BB rarity, but it is still scarce, and records are now assessed at county/regional level. Speaking personally, my local area's recording policies are not going to affect my own. But perhaps you feel differently, and are not happy to count birds which would be 'unacceptable' to your local records committee. If you won't count a tristis as a tristis unless you hear some sort of vocalisation, fine. Who am I to dictate how you should handle your own records?

As for me though, a sight-only record will be fine.

What I've summarised in this post is my own little tristis odyssey, and the sentence above is where it's taken me. Hope you've enjoyed the ride...


I don't normally do this, but I want to close with just a few words of appreciation for help along the way. Thanks go to Martin Collinson and Mark Lewis, for kindly sending me pdf copies of their respective BB papers; to Mike Langman, Joe Stockwell, and several Twitterati for encouragement of various kinds; to Richard Phillips for the smart photo of the Chideock WRC bird, and finally to Lee Evans for some forthright debate. I know Lee will disagree with my conclusion, but that's okay, he doesn't have to live with my questionable standards.

16 comments:

  1. Thoroughly educational, enjoyable and level-headed. I didn't even know Lee was still alive, do say hello to the ol' bean for me.

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    1. Thanks very much Seth.

      Lee is on Twitter at @LeeEvansBirding, where he can often be found holding forth in typically robust fashion. Always good value :-)

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    2. A very handy summary Gavin thanks. There were some questions locally about tristis ID so I will pass the link on.

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    3. Thanks Alastair. Obviously the summary here is just my personal take on tristis ID, but I get the impression that I am not alone in this approach. I can understand why some might be more cautious, especially where Sibe Chiff is a real rarity locally. At one time I would have been in that camp too, but after reading up on them I no longer feel that way.

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  2. And over 3000 viewings for your video of the Tristis so far Gav. This is clearly of interest.

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    1. Wow! I've just seen that Ric. Very unexpected.

      So...you're a secret Twitter lurker... ;-)

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  3. Not really Gav, but this last posting of yours was in my mind during yesterday's 12 mile run through the mud.

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    1. Ha ha! Glad to have provided a distraction from the mud, Ric!

      I would like to have posted the video here on the blog. I have found a couple of ways to do so, but for one reason or another I'm not particularly happy with them.

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  4. I wholeheartedly agree with you Gavin, with persistence many do call - and even sing in the spring (if they are males) - they will often remain (if not killed off by a harsh winter) well into April and even early May - Siberia is too cold to return to earlier than end of May/June! They moult much later than collybita, I've seen and photographed individuals moultling and re-growing flight feathers in April.

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    1. Thanks Mike, that's all very encouraging to know. I've become quite smitten by the little things and would love to hear one of them sing, so I can see there will be some uncharacteristic spring visits to the sewage works!

      I thought your comment to me about there being no need to 'muddy the waters' was very valid, and it came to mind many times during my reading on this topic. It would be so easy to do exactly that...and so unnecessary.

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  5. Hey Gavin. I've obviously read some of the same papers as you, initiatated by finding pale chiffs at Crewkerne WTW over recent winters (2 present this winter). I came to the same conclusion as you. Especially as they almost never call.

    One thing I have done in the absence of calling, is play a little bit of tristis song (Not sure how you feel about using recordings). This year's birds, who always stick very closely together within the throng of collybita, reacted very strongly. They didn't call or sing, but both rose up a small tree with one flicking wings and tail and the other going into a full wing shiver. Other chiffs present completely ignored it.

    Ken

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    1. Thanks for your comment Ken, it's good to know others are independently coming to the same conclusions too. I've been trying tristis playback also, but until recently had underwhelming results, just a few seconds wing-quivering followed by seeming indifference. But see this post from 8th Jan...response exactly as you describe:

      https://notquitescilly2.blogspot.com/2020/01/a-song-and-dance.html

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  6. Gavin, I don't think I reached my conclusion as rigorously as you. I was just frustrated with the "pale chiffs aren't tristis/pale chiffs are tristis" and "what about fulvescens/forget fulvescens". So when the Dutch study came back with the result that "all unusual chiffs are sibes and even some that don't look that unusual are also tristis" (I'm taking liberties with my paraphrasing), laziness meant that I gave up trying too hard and accepted that I would call any pale chiffs with dark bare parts and well-marked heads, tristis... but it still feels good to back it up with response to playback.

    I've had pretty lame responses from tristis to playback before. I wonder if their breeding so much later means they need more of a trigger to get much response. E.g. collybita (which are closer to breeding both in time and space) may respond quite freely to colly playback. Tristis (with many miles and many months to breeding) might need the sun shining and warm temperatures, lots of active insects and a full belly before they feel 'breedy' enough to respond. I know what I mean - but not sure if I'm making sense to others.

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    1. Yep, I know what you mean, and it seems logical to me. Best response I've had was on a mild day when one or two collybita were having a half-hearted little sing.

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  7. Overall, I agree with the findings, except for one very important point. Studying these chiffchaffs for years, particularly the grey/green 'fulvescens-types', reveals that in spring, when often many linger towards March, they begin singing and that's where it all goes pear-shaped. You will find that the song is very much on a 'chiff' 'chaff' theme and NOTHING like the very characteristic, and very different song of the pukka beige-type pure tristis. This leads me to believe that they are intergrades rather than separate species/sub-species, although the squeaky call they make (largely a metallic 'chep' note) is quite unique (although, again, quite different to the very plaintive, solemn, piping note of tristis)

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    1. Lee, many thanks for your comment. I think it is safe to say that your experience of these birds far exceeds my own, and if that is what you have found regarding the 'fulvescens' types you have seen, fair enough. The papers I have read make it clear that the contact zone is a genetic mess, the result of many generations-worth of interbreeding. Logically some of our birds will be from this area. I accept that. However, the only bird I have thus far heard call was a 'fulvescens' type. Its call was (to my ears) identical to the recordings of pure tristis that I have heard, ie, what you describe as the 'plaintive, solemn, piping note of tristis'. Also, the only other local Sibe Chiff I have heard call (back in 2004) produced exactly the same sound (I revisited my description to check) and was also a 'fulvescens' type.

      Obviously I would like very much to hear them start singing come the spring, but in the meantime I am still comfortable calling them 'tristis'. I accept that it is likely a small percentage of our birds will be intergrades, but as the 'fulvescens' plumage type seems to extend well into the West Siberian Plain, I also believe that most will not.

      If the 'fulvescens' type birds can call exactly as a tristis should (and they definitely can! In addition to the mere two that I have heard there are plenty of sound-recorded examples) and can return a DNA result that says 'tristis', that is certainly good enough for me. As far as I am aware (from what I've read on the subject) no 'fulvescens' type that has had its DNA analysed has yet returned any result other than tristis. For me - until proven otherwise - DNA rules!

      I suspect that you and I are going to have to agree to differ on this one Lee! Thanks very much for the discussion though, it has kept me on my my toes...

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