Iberian Chiffchaff in Lancashire
When I visited Spurn back in May, I recall being told that an Iberian Chiffchaff in Lancashire was still lingering. I was unable to divert to the site before getting a train from Preston on my way back, however, and I soon forgot about this bird, assuming that it had departed. I was woken out of this facile assumption, however, on the morning of Monday 3rd June, when I saw a post on social media linking to a blog post about someone having seen the bird the weekend just gone. At that stage, I had made plans to visit my friend Seán Ronayne in Catalunya for the coming weekend, so I started to peruse train and bus timetables online and see if I could divert on my way to Manchester Airport. As this proved feasible, I made the necessary arrangements, and eagerly got a bus from Lancaster to Pilling early on the morning of 7th June.
The bus passed directly by the amenity area where this Iberian Chiffchaff has been holding territory, and, indeed, within 2 minutes or less of being dropped off, I could hear the bird in song, and, a few minutes later, I'd managed to see it also. The pressure taken off me, and with time on my hands, I could then afford to spend time with the bird, listening to it, making sound recordings, trying to get pics and generally enjoy the experience while gaining valuable familiarity with a species that is on the Irish List but which is presumably overlooked as well.
It soon became apparent that the bird was giving song strophes that were very typical 'in your face' Iberian Chiffchaff song, and others that, while 'distinctive' somehow, were a lot more confusable with the typical song of Common Chiffchaff...certainly, I could see these song types being written off as just being an 'odd Chiffchaff song' if one didn't then also hear the more typical phrases.
Given the existence of 'mixed singers' within the (narrow) contact zone between Common and Iberian Chiffchaffs, and the fact that hybridisation (though rare) does occur, the field identification of Iberian Chiffchaff demands due care to eliminate presumed hybrids or Common Chiffchaffs that have somehow picked up some Iberian song elements. Of course, that being said, unless every Iberian Chiffchaff candidate is DNA sampled, even a cautious approach may lead to an occasional bird being accepted that possesses some collybita DNA, but, then, and increasingly in today's ornithological world, one could say that about out of range records of many things, certainly large gulls spring to mind.
It is worth providing a brief summary here, with an apology to anyone who reads this and knows all about the facts already, of what is known about the song of Iberian Chiffchaff, the implications for field identification, and what exactly constitutes a mixed singer. Anyone interested in more in depth explanation of the issues can be advised to check out the literature. Basically, Iberian Chiffchaffs have two main song types, which are often termed the advertising song and the conflict song. Common Chiffchaff has these two song types also, incidentally, but, in that species, the two song types are incredibly similar. In Iberian Chiffchaff, the 'advertising' song is the typical song most associated with the species. Typical 'advertising' song contains three motifs: initial 'djup' or 'chiff' type notes, upwardly inflected 'wheet' notes and a terminal rattle. Individual song strophes may leave some of these elements out, or give fewer or more of one element from another strophe, but basically the advertising song is generally quite distinctive.
The conflict song is much more similar to that of Common Chiffchaff, and there is a very real risk, if one isn't expecting this, of dismissing a bird that otherwise sounds good as a 'mixed singer', given the existence of Common Chiffchaff-like song elements. Indeed, any bird giving both advertising and conflict songs will certainly sound somewhat like a Common Chiffchaff at times, this is perfectly normal. A 'mixed singer' would give elements typical of Iberian and Common Chiffchaffs within a single strophe of advertising song, or the phrases would last longer than the typically short advertising song strophes of Iberian.
Given my being away from my laptop for a few days after seeing (and hearing/sound recording) this Iberian Chiffchaff, and thus unable to edit my sound recordings, I made a video with my phone and posted that on Twitter. The bird wasn't rubbished, or even strongly questioned as such, but the possibility that one slight element was reminiscent of Common Chiffchaff at one point was raised. Especially as I had no prior field experience with the species, I welcome such questioning, a more regular feature of 21st century birding but also a reminder of the potential for the Internet as both a repository of knowledge and a means of facilitating open discussion between birders from across the world. It certainly made me knuckle down and listen in detail to my own recordings once I was able to download them to my laptop.
Regrettably, I never heard the bird call: on current knowledge, the call is thought to be diagnostic. However, I asked around, and it transpired that Chris Batty managed to hear and sound record it calling two days after my visit. The calls noted matched those of Iberian Chiffchaff, both aurally and in terms of the sonogram generated. While I was already pleased with it for myself, it's good to hear that that extra detail was also noted.
Having gone through the basics, here are a few of my own sound recordings of the bird.
Note the slightly 'bubbling' calls in between song strophes, similar can often be heard from male Common Chiffchaffs between song strophes when on a territory. The song itself consists solely of elements associated with Iberian Chiffchaff advertising song, though the terminal rattle can sometimes be left out, and the number of other elements varies.
Again, as above, this seems to be quite typical Iberian Chiffchaff advertising song, with no hint of 'mixed singing'.
Some conflict song. Note that this sounds a lot more like Common Chiffchaff song, and could easily be overlooked as that, but, knowing that there was an Iberian Chiffchaff around, it did sound a little different, perhaps the individual song strophes seemed a little shorter, or something in the delivery. Nevertheless, this was a practical reminder for me not to be so quick to dismiss any 'odd Chiffchaff' even if it didn't first appear to be Iberian: it could be conflict song.
A section of sonogram from the recording used in XC480890. Note the four almost vertical lines representing the 'djup' notes, a single upslurred 'wheet' and a subterminal rattle. Also note the narrower frequency range, mainly between 3-7kHz with very limited elements of the song exceeding 6kHz (though there are harmonics which appear above the actual notes), and the fact that the strophe is so short, this one coming in at about 2 seconds long (typically over 4 seconds long in Common Chiffchaff).
As far as the bird's appearance went, I'd not feel confident identifying a silent Iberian Chiffchaff with a degree of certainty, though nothing in this bird's appearance seemed wrong for that species, and a combination of subtle features added up to make this bird something that would attract a second glance if seen well.
The appearance of Iberian Chiffchaff is quite subtle, as can be seen from my images! At the risk of simplifying matters, it can even be tricky to separate one from Willow Warbler, as they can be yellower on the face and upper breast at least, and a bit greener above, than on Common Chiffchaff, with a more prominent supercilium, less obvious broken eye-ring (especially poorly marked above the eye), paler base to the lower mandible and paler legs, on average, all features more associated with Willow Warbler. The primary projection, though hard to assess from these images, is a little on the short side, the legs are brownish rather than a paler and more orange-toned colour (but some Willows have darker legs, of course), and the bird arguably 'felt' more like a chiffchaff in life, but the risk of overlooking a silent Iberian Chiffchaff as a Willow Warbler, at least on a superficial view, is very real. The very strong, almost buttercup yellow, tones to the fore-supercilium were distinctive on this individual, and brighter than on many/most Willows, and the eye stripe was probably weaker than on most also.
Given that an overwhelming majority of accepted North-western European records of Iberian Chiffchaff have related to singing birds, one might imagine that at least spring females are being overlooked, and perhaps some occur in autumn also (c.f. other southern warblers such as the subalpine warbler complex or Melodious Warbler). The recent increase in vagrancy is probably largely related to greater observer awareness, though it is also possible that the species is undergoing an increase and/or range expansion. Most remarkably, an apparently pure pair of Iberian Chiffchaffs (the female was heard to call) bred in Wales in 2015, fledging at least seven chicks from two broods, so perhaps something is going on with them. Time, and enough primed and ready birders, will tell...
REFERENCES: Much of what was written above concerning the typical vocalisations of Iberian Chiffchaff, and the pitfalls presented by 'mixed singers', was taken from the following article.
Collinson, J.M. and Melling, T. Identification of vagrant Iberian Chiffchaffs - pointers, pitfalls and problem birds British Birds Vol. 101 page 174-188 (April 2008).
The bus passed directly by the amenity area where this Iberian Chiffchaff has been holding territory, and, indeed, within 2 minutes or less of being dropped off, I could hear the bird in song, and, a few minutes later, I'd managed to see it also. The pressure taken off me, and with time on my hands, I could then afford to spend time with the bird, listening to it, making sound recordings, trying to get pics and generally enjoy the experience while gaining valuable familiarity with a species that is on the Irish List but which is presumably overlooked as well.
It soon became apparent that the bird was giving song strophes that were very typical 'in your face' Iberian Chiffchaff song, and others that, while 'distinctive' somehow, were a lot more confusable with the typical song of Common Chiffchaff...certainly, I could see these song types being written off as just being an 'odd Chiffchaff song' if one didn't then also hear the more typical phrases.
Given the existence of 'mixed singers' within the (narrow) contact zone between Common and Iberian Chiffchaffs, and the fact that hybridisation (though rare) does occur, the field identification of Iberian Chiffchaff demands due care to eliminate presumed hybrids or Common Chiffchaffs that have somehow picked up some Iberian song elements. Of course, that being said, unless every Iberian Chiffchaff candidate is DNA sampled, even a cautious approach may lead to an occasional bird being accepted that possesses some collybita DNA, but, then, and increasingly in today's ornithological world, one could say that about out of range records of many things, certainly large gulls spring to mind.
It is worth providing a brief summary here, with an apology to anyone who reads this and knows all about the facts already, of what is known about the song of Iberian Chiffchaff, the implications for field identification, and what exactly constitutes a mixed singer. Anyone interested in more in depth explanation of the issues can be advised to check out the literature. Basically, Iberian Chiffchaffs have two main song types, which are often termed the advertising song and the conflict song. Common Chiffchaff has these two song types also, incidentally, but, in that species, the two song types are incredibly similar. In Iberian Chiffchaff, the 'advertising' song is the typical song most associated with the species. Typical 'advertising' song contains three motifs: initial 'djup' or 'chiff' type notes, upwardly inflected 'wheet' notes and a terminal rattle. Individual song strophes may leave some of these elements out, or give fewer or more of one element from another strophe, but basically the advertising song is generally quite distinctive.
The conflict song is much more similar to that of Common Chiffchaff, and there is a very real risk, if one isn't expecting this, of dismissing a bird that otherwise sounds good as a 'mixed singer', given the existence of Common Chiffchaff-like song elements. Indeed, any bird giving both advertising and conflict songs will certainly sound somewhat like a Common Chiffchaff at times, this is perfectly normal. A 'mixed singer' would give elements typical of Iberian and Common Chiffchaffs within a single strophe of advertising song, or the phrases would last longer than the typically short advertising song strophes of Iberian.
Given my being away from my laptop for a few days after seeing (and hearing/sound recording) this Iberian Chiffchaff, and thus unable to edit my sound recordings, I made a video with my phone and posted that on Twitter. The bird wasn't rubbished, or even strongly questioned as such, but the possibility that one slight element was reminiscent of Common Chiffchaff at one point was raised. Especially as I had no prior field experience with the species, I welcome such questioning, a more regular feature of 21st century birding but also a reminder of the potential for the Internet as both a repository of knowledge and a means of facilitating open discussion between birders from across the world. It certainly made me knuckle down and listen in detail to my own recordings once I was able to download them to my laptop.
Regrettably, I never heard the bird call: on current knowledge, the call is thought to be diagnostic. However, I asked around, and it transpired that Chris Batty managed to hear and sound record it calling two days after my visit. The calls noted matched those of Iberian Chiffchaff, both aurally and in terms of the sonogram generated. While I was already pleased with it for myself, it's good to hear that that extra detail was also noted.
Having gone through the basics, here are a few of my own sound recordings of the bird.
Note the slightly 'bubbling' calls in between song strophes, similar can often be heard from male Common Chiffchaffs between song strophes when on a territory. The song itself consists solely of elements associated with Iberian Chiffchaff advertising song, though the terminal rattle can sometimes be left out, and the number of other elements varies.
Again, as above, this seems to be quite typical Iberian Chiffchaff advertising song, with no hint of 'mixed singing'.
Some conflict song. Note that this sounds a lot more like Common Chiffchaff song, and could easily be overlooked as that, but, knowing that there was an Iberian Chiffchaff around, it did sound a little different, perhaps the individual song strophes seemed a little shorter, or something in the delivery. Nevertheless, this was a practical reminder for me not to be so quick to dismiss any 'odd Chiffchaff' even if it didn't first appear to be Iberian: it could be conflict song.
As far as the bird's appearance went, I'd not feel confident identifying a silent Iberian Chiffchaff with a degree of certainty, though nothing in this bird's appearance seemed wrong for that species, and a combination of subtle features added up to make this bird something that would attract a second glance if seen well.
The appearance of Iberian Chiffchaff is quite subtle, as can be seen from my images! At the risk of simplifying matters, it can even be tricky to separate one from Willow Warbler, as they can be yellower on the face and upper breast at least, and a bit greener above, than on Common Chiffchaff, with a more prominent supercilium, less obvious broken eye-ring (especially poorly marked above the eye), paler base to the lower mandible and paler legs, on average, all features more associated with Willow Warbler. The primary projection, though hard to assess from these images, is a little on the short side, the legs are brownish rather than a paler and more orange-toned colour (but some Willows have darker legs, of course), and the bird arguably 'felt' more like a chiffchaff in life, but the risk of overlooking a silent Iberian Chiffchaff as a Willow Warbler, at least on a superficial view, is very real. The very strong, almost buttercup yellow, tones to the fore-supercilium were distinctive on this individual, and brighter than on many/most Willows, and the eye stripe was probably weaker than on most also.
Given that an overwhelming majority of accepted North-western European records of Iberian Chiffchaff have related to singing birds, one might imagine that at least spring females are being overlooked, and perhaps some occur in autumn also (c.f. other southern warblers such as the subalpine warbler complex or Melodious Warbler). The recent increase in vagrancy is probably largely related to greater observer awareness, though it is also possible that the species is undergoing an increase and/or range expansion. Most remarkably, an apparently pure pair of Iberian Chiffchaffs (the female was heard to call) bred in Wales in 2015, fledging at least seven chicks from two broods, so perhaps something is going on with them. Time, and enough primed and ready birders, will tell...
REFERENCES: Much of what was written above concerning the typical vocalisations of Iberian Chiffchaff, and the pitfalls presented by 'mixed singers', was taken from the following article.
Collinson, J.M. and Melling, T. Identification of vagrant Iberian Chiffchaffs - pointers, pitfalls and problem birds British Birds Vol. 101 page 174-188 (April 2008).
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