On a related note here is a mixed singing Willow Warbler / Chiffchaff recorded at Woolmer Forest, Hampshire, May 2013. Click here







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Mixed singing and aberrant
Phylloscopus Warblers

Every year there are reports of mixed singing Chiffchaff species / Willow Warblers in Hampshire, 'mixed singing' or 'song switching' is common but easy to overlook.

For anyone interested in mixed singers and hybrid
Phylloscopus - I'd recommend a read of this article.

Apparent Hybrid, Iberian Chiffchaff (Phylloscopus ibericus) X Common Chiffchaff (Phylloscopus collybita)
Sandy Point, Hayling Island, Hampshire, Spring 2014
Click here for a sound clip of this birds song



The presumed hybrid 'mixed singing' chiffchaff arrived at sandy point Hayling Island in mid March and remained on territory singing daily through April.



Andy Johnson who found this bird and observed it almost daily during its stay
has made or agreed with the following statements.

· The sandy point bird's song has remained consistent since its arrival.

· It's song consistently contains elements comparable to Iberian Chiffchaff (Phylloscopus ibericus) song

· The bird includes elements in its song which are much like the familiar Common Chiffchaff (Phylloscopus collybita) song, not always but either routinely or when it is agitated and using a conflict song in clashes with local or migrant Common Chiffchaffs. Iberian Chiffchaff’s conflict song is reported to be much like the familiar song of Common Chiffchaff. (It also does a conflict song in reaction to people in close proximity!)

· This bird has been heard to call ‘hweet’ as Common Chiffchaff

· The consistent ibericus elements in the birds song are surely too embedded to dismiss this bird as a ‘Common’ Chiffchaff that has come into contact with Iberian Chiffchaffs on migration and for some reason, ‘impersonates’ their song.

· The consistent ibericus elements in this bird’s song are too much like Iberian Chiffchaff to dismiss the bird as a Common Chiffchaff with an aberrant song.

· The bird delivers a consistent song that contains elements that can be likened to the song of both species but that cannot be attributable solely to either one species, most likely because it is a hybrid.

Click here for a sound clip of this birds song

Here is a recording of typical Iberian Chiffchaff song

"In the overlap zone between Siberian Chiffchaff and Common Chiffchaff of the form abietinus, extending NW from the southern Urals, there is also a significant level of 'mixed song' (Lindholm 2008; Marova et al 2009). Here hybridization between the two forms has also been inferred, from a combination of morphological, genetic and bio-acoustic characters (Marova et al 2009)."

"The ranges of Common and Iberian Chiffchaffs overlap in a narrow, 20-km zone in the western Pyrénées around the France/Spain and the two species hybridise.' 'and 8.6% of birds are mixed singers, giving song bursts that consist of elements of songs from both species"

Richard Ford - with thanks to Andy Johnson
www.digitalwildlife.co.uk

 

Here are a few quotes from sources on the web and some food for thought:

"The ranges of Common and Iberian Chiffchaffs overlap in a narrow, 20-km zone in the western Pyrénées around the France/Spain and the two species hybridise.' 'and 8.6% of birds are mixed singers, giving song bursts that consist of elements of songs from both species"

"In the overlap zone between Iberian Chiffchaff and nominate Common Chiffchaff in NE Spain and SW France, most individuals combining elements of the two species songs are true 'mixed singers'. Using genetic AFLP analysis, most 'mixed singers' have been shown to be hybrids (Bensch et al 2002)."

And the two species have hybridised in Britain!

"Mixed singers have also been recorded from the breeding range of Iberian Chiffchaffs outside the hybrid zone"

"In the context of spring vagrancy, Iberian chiffchaff has two major song types: an advertising song used by males trying to attract a mate and a conflict song used primarily during antagonistic interactions with other males."

''The conflict song of Iberian is very similar to that of Common but the advertising song is more variable and contains song elements not used by Common Chiffchaff''

On site at Sandy point while reviewing my recordings, the Sandy point bird responded to a recording of its own Iberian type song by singing a Common Chiffchaff like song.

"As described above, the conflict song of Iberian Chiffchaff, given in response to, for example, a rival male, is very similar to the familiar 'chiff chaff chiff chaff ' of Common Chiffchaff. The definition of 'mixed singer' is reserved for those birds that use song elements characteristic of both Iberian and Common Chiffchaff within a
single advertising song."

The Sandy Point bird clearly does.

"These birds might sing songs similar to those of collybita or ibericus; more than three song motifs in an 'Iberian' song may be a clue that the bird is a mixed singer (Salomon & Hemim 1992; Marc Salomon pers. comm.), and any Iberian-type chiffchaff habitually singing songs more than four seconds long is suspect."

The second burst of song in the above recording can be timed at just under 7 seconds.

"Common Chiffchaff-like elements within the songs of an Iberian Chiffchaff may represent normal elements of the conflict song of the latter, and may also represent shared 'ancestral' or primitive song elements that are retained, to some degree, in both species"


Mixed Singing Willow Warbler / Chiffchaffs

On a related note here is a mixed singing Willow Warbler / Chiffchaff i recorded at Woolmer Forest, Hampshire, May 2013, it returned to the same territory for four years. Click here for the song. It looked like a rather dull Willow Warbler photo below.
Hybrid Chiffchaff x Willow Warbler?! Why not?




Additionally for info here are variuse calls and song of Siberian Chiffchaff (Phylloscopus (collybita) tristis) to add to the mix!

"In the overlap zone between Siberian Chiffchaff and Common Chiffchaff of the form abietinus, extending NW from the southern Urals, there is also a significant level of 'mixed song' (Lindholm 2008; Marova et al 2009). Here hybridization between the two forms has also been inferred, from a combination of morphological, genetic and bio-acoustic characters (Marova et al 2009)."



Thanks to Steve Mansfield for the recording of the Shortheath Common bird of April 2017
Click here What is it?

I went to see and hear this bird on 17th April 2017 to my mind there is nothing Willow Warbler or Iberian Chiffchaff about it but a fasinating bird with a most unusual song for a Common Chiffchaff. A video where you can hear the song below.


Photos, song and calls of the bird in the video below. On the appearance and calls it would be hard not to dismiss it as a Common Chiffchaff collybita. But can comparisons be drawn between this bird's song and the song of Siberian Chiffchaff P. (collybita) tristis. Could this be a bird from the abietinus / tristis overlap zone ?

 

 

I find these birds very interesting and would welcome comments!


Richard Ford
www.digitalwildlife.co.uk