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
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.
Apparent Hybrid, Iberian Chiffchaff (Phylloscopus
ibericus) X Common
Chiffchaff (Phylloscopus collybita)
· 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 Chiffchaffs 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 birds 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.
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)."
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"
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
"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."
"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"
"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)."
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!