Willow Warbler - mixed singer (Whiffwhaff?)

[Peter Stronach]

Hi all

i was undertaking a common birds census last week in Somerset and came across a Willow Warbler which was singing unusually. The bird would sing a series of songs, some of the series would be pure Willow Warbler, others would be Willow Warbler to start and finish but in the centre there would be an exact imitation of a Chiffchaff. The amount of Chiffchaff notes varied within any given series of songs. The bird looked and acted, to my eyes, like a Willow Warbler.

I have attached a photo of the bird singing and i have also uploaded two videos of the bird singing onto youtube, link below:

http://www.youtube.com/watch?v=38rP-PBsabo

http://www.youtube.com/watch?v=6Q3jf8At47w

During a search of the internet i have found very similar songs on the Dutch birding website, where a song starts and finishes Willow Warbler with a Chiffchaff middle section. On the website these have been labelled as hybrids.

Has anyone else had experience of similar birds?. Also does anyone know whether hybrids between the two species have ever been proved for definite.

thanks

Peter

[PeterD]

Peter

Very good picture. Nice song story too. Perhaps the bird is training as an interpreter.

Peter

[Colin Key]

Willow Warbler. I cannot hear Chiffchaff (but can hear a helicopter!).

Colin

[Bonsaibirder]

Hi Peter,

I think the normal phrases in your second video clip demonstrate that the "Chiffchaff-like" part of the song in the first video (and the very last phrase of the second one) is actually just an exaggerated version of a normal Willow Warbler song. I have heard Willows Warblers do that before but perhaps not quite such extreme examples.

Cheers,

Steve

[anthonydodds]

Willow Warbler for me.

[winterdune]

Here's a Chiffy with Willow influences:
http://www.birdforum.net/showthread.php?t=113203

[Peter Stronach]

Interesting blog post on this subject - http://gwentbirding.blogspot.com/2011/04/theyre-everywhere.html

[ARD]

The cited paper by Bensch et al refers to a 'mixed singing' Chiffchaff. However, from correspondence with Prof Bensch, this was in fact what I prefer to call a 'song switcher'. That is, a bird which utters a complete song-phrase of one species followed by a complete song-phrase of the other species. In a true 'mixed singer', each song-phrase comprises an intimate mixture of notes of the two species. Although not proven, and no doubt there are exceptions, it seems to me probable that 'song switching' is more likely to arise from one (purebred) species copying the song of the other, whereas true 'mixed singing' is more likely to indicate a hybrid. Certainly, there are a number of cases of apparently pure Willow Warblers switching to Chiffchaff song while the case described by Bensch et al involved a Chiffchaff 'song switching'. Conversely, the proven hybrids between Iberian Chiffchaff and Common Chiffchaff (Bensch et al 2002, Mol Biol 11: 473-481), and the apparent hybrids between Siberian Chiffchaff and Common Chiffchaff (Marova et al 2009, Doklady Biol Sci 427: 384-386), frequently utter genuine 'mixed song'.

[MichaelF]

However, from correspondence with Prof Bensch, this was in fact what I prefer to call a 'song switcher'. That is, a bird which utters a complete song-phrase of one species followed by a complete song-phrase of the other species.
That agrees with what I've heard several times, where Chiffchaffs will imitate Willow Warbler at this time of year to try and keep newly arrived Willow Warblers out of their established territories. After a couple of days, they give up and return to singing just normal Chiffchaff.

[Martin Garner]

Have you seen and listened to this one?

http://birdingfrontiers.com/2011/04/09/iffy-chiffy/


Its what I think is a Chiffchaff which has learnt etc. some Willow Warbler and is mixing it up... See what you think.

Martin

[MichaelF]

Have you seen and listened to this one?

http://birdingfrontiers.com/2011/04/09/iffy-chiffy/


Its what I think is a Chiffchaff which has learnt etc. some Willow Warbler and is mixing it up... See what you think.

Martin
That's the same as I've heard several times as in my previous post:smile:

[ARD]

This one seems to be a genuine 'mixed singer', at least in the opening few seconds of the recording. With such 'mixed' song phrases, the result sounds (at least to human ears) like neither species. It is intriguing to speculate how it would be regarded by 'competitors'. Also, Oscine passerines are deemed to learn their songs by copying an adult 'tutor'. Thus, true 'mixed songs' are doubly intriguing, as it has always struck me that a true 'mixed song' cannot be copied. A learned song may well be modified subsequently, certainly. However, if copying is the fundamental mechanism, then it seems easier to understand 'song switching' than the (prima facie) more complex integration of indivdidual notes into a truly 'mixed song'.

Alan

[ARD]

Today (April 18th) in the Blythe Valley in West Midlands I came on a Willow Warbler giving a 'combination song' with some (though not total) resemblance to Martin's Chiffchaff song. In plumage and structure, the West Midlands bird appeared like a standard Willow Warbler in all respects. One in ten song phrases was 'classic' Willow Warbler but others either began or finished with a Coal Tit-like 'wee-choo' or 'wee-choo-choo'. There was a hint of Chiffchaff in the 'double notes' but much more similar to Coal Tit.
Alan

[Darryl]

Here's another recording of another mixed singing Willow Warbler, I have had three in recent years and all have been "genuine mixed singers", they do produce whole phrases which, superficially, sound like pure Willow Warbler or Chiffchaff amongst the mixed phrases but even these often have subtle anomalies (e.g. in tempo or rhythm) as compared to a normal bird...

http://soundcloud.com/darrylspittle/goldcliff-mixed-singing-willow

Regarding some of the comments above,...

Does a mixed singer sound like "neither species" to human ears? They sound like both to me, hence the fact I say to myself "Oh look, another phylloscopus singing mixed Chiffchaff and Willow Warbler song" as opposed to "WTF is that!"

Re competition, at least two birds have held territories in two or more years on my patch, so they can apparently compete successfully with other males to some extent. Not sure exactly how successful they are at attracting females and producing young mind.

Re song learning, oscine passerines do not simply "learn their songs by copying an adult tutor", the process is sufficiently flexible, and includes more than enough opportunities (either due to 'creativity' or error), for the production of novel combinations of song elements to produce mixed singing.

Cheers all,
Darryl

PS. At this time of year beware 'plastic' or 'pre-crystallised' singing, a 2nd calendar year bird sounding a bit weird right now might be perfectly normal in a week or two.

[Alex Lees]

PS. At this time of year beware 'plastic' or 'pre-crystallised' singing, a 2nd calendar year bird sounding a bit weird right now might be perfectly normal in a week or two.

An odd-sounding Chiff I had two springs ago (and discussed on here already: see here (http://www.freewebs.com/punkbirder/marchaugust2009.htm) 8th May) started off singing very oddly but then after a few weeks 'attained normality'. However phenotypically it had some characteristics e.g. green wash, long pp that seem at odds with the explanation that it was 'just' a 2-cal getting warmed up. One wonders whether hybrids (should they exist) starting out with a mixed song might eventually attain perfection of one of the parental song types?

[ARD]

Does a mixed singer sound like "neither species" to human ears? They sound like both to me, hence the fact I say to myself "Oh look, another phylloscopus singing mixed Chiffchaff and Willow Warbler song" as opposed to "WTF is that!"

Semantics here I fear! Even in a single song-phrase, when a so-called mixed song includes a long enough sequence of notes of one species followed by a long enough sequence of notes from the other (as in the first phrase on your recording), then each sequence sounds clearly like the appropriate species. However, when the notes become truly ‘mixed’ (as in the second song phrase on your recording) then the result becomes much less like either species. Although there is no absolute dividing line between the two structures, this is an important distinction I believe between ‘song switching’ and truly & consistently ‘mixed song’. (With one or two truly 'mixed singers' I have encountered, my initial rection has been very close to 'WTF is that?' ! )


Re song learning, oscine passerines do not simply "learn their songs by copying an adult tutor", the process is sufficiently flexible, and includes more than enough opportunities (either due to 'creativity' or error), for the production of novel combinations of song elements to produce mixed singing.


I am no expert on bird vocalisations and certainly I don’t pretend to be able to contribute substantially to a debate on song development techniques! What I have said (when it seems relevant) about song-learning and tutors in passeriformes is taken completely from the literature (e.g. the ground-breaking work of Thorpe (1961), and subsequent researchers, using isolate populations). One example among many is from Fehér et al (http://ofer.sci.ccny.cuny.edu/publications/cultural_evolution.pdf)(cited earlier on the Chiffchaff 'sweeoo' call thread): ‘Young male zebra finches develop individually distinct song by imitating adult males’. However, this is not to imply inflexibility. On the contrary, as Fehér et al demonstrated, over time ‘cultural influences’ will produce the fully-developed wild song even in an isolate population (i.e. even with a complete absence of tutors). That indeed (or so it seems to me) is the important point.

Alan

[ARD]

Postscript.

Semantics-wise, perhaps it will help if I repeat (or formalise) my definitions here (personal and totally unofficial - but hopefully helpful?).

Song switching: the juxtaposition of sensibly complete song-phrases from two species. In song switching the identity of the species with which each component is normally associated is immediately evident.

Mixed song: an intimate mixture, in a single song phrase, of individual notes from the songs of two species. In true mixed singing, the resultant song phrase may not closely resemble the normal song of either species. Example: In truly mixed singing between Willow Warbler and Chiffchaff, the result can recall Siberian Chiffchaff or even Greenish Warbler.

Of course, there will be instances which do not slot neatly into either of these categories (some may use both) but a majority appears to. My suggestion is that consistent, truly 'mixed singing' is more likely to indicate a hybrid origin than is song-switching. Certainly, from corespondence with those involved with the research, most individuals with 'combination songs' from the overlap zone between ibericus and collybita, and between tristis and abietinus, respectively, are mixed singers. Also, in the ibericus/collybita overlap zone, most 'mixed singers' have been shown by AFLP analysis to be hybrids (Bensch et al. 2002. 'Applied fragment length polymorphism analysis identifies hybrids between two [sub]species of warblers.' Molecular Biology 11: 473-481).

Alan

[ARD]

I referred earlier to a Willow Warbler in the West Midlands with an odd and assumed to be 'mixed' song. It was still present yesterday and I managed to obtain a recording of the song. This time some of the song phrases were more genuinely mixed rather than concluding with the aberrant notes. [P.S. see next contribution for update on the impression that this song was 'mixed']. For recording see here (http://www.deanar.btinternet.co.uk/general/articles/wwmixedsong.htm).
The recording comprises five song-phrases: first a (presumed) 'mixed' phrase; then a Willow Warbler phrase followed by a 'mixed' phrase; then another 'mixed' phrase; then a normal WW phrase; and finally another 'mixed' phrase.
It is interesting to compare this recording with that on Martin's site (http://birdingfrontiers.com/2011/04/09/iffy-chiffy/). Each bird reverts on occasion to it's 'normal' song (i.e. Willow Warbler in the West Midlands bird and Chiffchaff in Martin's bird) yet the presumed 'mixed' phrases are quite similar. The 'mixed phrases' don't announce their origin with total certainty (and would be perplexing in isolation). However, that they are similar in the two birds would seem to confirm that the songs of WW and Chiffchaff are indeed involved in each case. The structures in the sonograms lend support to this.
Together with all the 'sweeoo' calling Chiffchaffs, this is proving to be an interesting Spring for phylloscopus vocalisations!

Alan

[ARD]

I've been analysing the recordings of both the West Midlands and Martin's bird. Both contain 'double notes' which have some resemblance to Coal Tit and in each case the 'abnormal' song phrases sound disconcerting. However, I've slowed down the two recordings and this shows an interesting outcome. Martin's bird indeed appears to be a genuine 'mixed singer' (see contributions above). On first hearing, the West Midlands bird also suggests a true mixed singer but it turns out NOT to be a genuine mixed singer as defined above. It is only the speed of delivery of the 'odd notes' (and to a lesser extent their timbre) which suggests Willow Warbler. When slowed down to 75% of normal speed, these odd components reveal themselves as more-or-less 'standard' Chiffchaff phrases in structure - but delivered at Willow Warbler speed. Thus, the song of the West Midlands bird in fact involves juxtaposing complete song phrases of the two species (i.e. 'song switching'). Nevetheless it is STILL disconcerting because the Chiffchaff phrases are delivered with unusual rapidity! Updated details here (http://www.deanar.btinternet.co.uk/general/articles/wwmixedsong.htm).

[I see that I am the only one pursuing this thread, so I'll stop there unless there is further input from others.]

regards, Alan

[bitterntwisted]

I see that I am the only one pursuing this thread, so I'll stop there unless there is further input from others.

I'm still here, Alan, and grateful for all the excellent info.

I found my own Whiffwhaff while doing a TTV at Little Brickhill, on the Beds/Bucks border at the weekend, and popped back Tuesday morning to get a couple of recordings before coming back north.

As can be heard in the videos linked below, my bird sings mostly Willow Warbler, but intersperses brief Chiffchaff phrases either at the beginning or in the middle of some song passages. On the definitions above it is a song switcher rather than a mixed singer. The videos aren't brilliant visually but should be enough to convey the song switching. Unfortunately faffing with bins, phone and pocket camera I missed some of the best example passages.

Video 1: http://vimeo.com/22947659
Video 2: http://vimeo.com/22954921

I hope it's clear which bird is singing; there is at least one other Chiffchaff and Willow Warbler in background, and you can also hear the Chiffchaff sample I played to the bird. It reacted quite vociferously to Chiffchaff song, coming boldly to investigate the source and flying all around me. However, it reacted more aggressively still to Willow Warbler when I played that. In response to Chiffchaff, it sang mixed; in response to Willow Warbler it seemed to sing exclusively Willow Warbler.

The bird looked to me like a Willow Warbler, albeit a fairly dull, browny one. I'm no great student of feather tracts and plumage tones, but it had a Willow Warbler face, with no pronounced eyering, a beady eye, and the upward-pointing 'Pinocchio bill' impression caused by the angle between the super and a pale bill-base, moderately pale legs, and seemingly quite long wings. Curiously, however, In the first posted video, (0743) at 0:23, it
appears to dip its tail?

If anyone is interested in such mysteries, the bird was at SP912330, almost at the bottom of the hill. Follow the wide bridleway first past the clear fell and then past all the rhododendrons and exotic conifers from http://tinyurl.com/whiffwhaffbridleway. Its territory crosses the bridleway where the rhodedendrons thin out, and it will sing from high in the oak to the east on one side or low in the willows to the west on the other.

Graham

[ARD]

In the second video there seems to be at least an element of genuine mixed singing.

I am about to launch a new thread regarding another 'combo singer' I encountered yesterday. It was (apparently) a Willow Warbler with some Chiffchaff notes juxtaposed but also gave some song-phrases which strongly recalled Iberian Chiffchaff! Probably better I think to launch this as a new thread with a more direct title.

Alan

[Peter Stronach]

ARD and others, many thanks for all the interesting posts and links!. Found another song switching Willow Warbler, this time in Oxfordshire, which appears to be holding territory, made some recordings:

First track, professional sound recordists may have nightmares about the start of this but please bear with it! These phrases are almost entirely Chiffchaff:

http://soundcloud.com/peter-stronach/20150515-180805-1

Second track, a mixed up phrase followed by an almost normal Willow Warbler song, then followed by phrases which increasing add Chiffchaff:

http://soundcloud.com/peter-stronach/20150516-013436

It has been on territory for a week and doesn't appear to be getting any purer with it's song phrases.

Peter