An unusual Chiffchaff in Farley

An unusual Chiffchaff has been present in Farley wood since at least last Sunday when it was found by Steve Mann. The song is quite unlike that of the familiar Common Chiffchaff and the bird has a number of features which point to its identity as Iberian Chiffchaff, a rare visitor to Britain.

In bright sunlight the bird has white under parts flecked with yellow across the chest and on the flanks. The bill looks long and pointed compared to Common Chiffchaff and the lower mandible is orange fading darker towards the tip.

The legs and feet are dark, looking dark red in bright sunshine.

Silky white underparts flecked with yellow in bright sunlight and orange base to the bill

When singing the bird has a habit of fluffing its breast feathers and lowering its body on to the branch whilst raising its rump feathers

The primary projection and spacing is slightly different in the two species but is not clear on the photos I've obtained so far

It often sits with the rump feathers raised, you may just be able to see the primary tips on this photo

What may be a critical clue to the birds identity can be seen on the spread wing when the bird is caught in flight. It looks like the outer 6 primaries are all fresh with unworn tips whilst the visible primaries 7 and 8 have worn tips which indicates that these and presumably 9 and 10, which are not clearly visible in the photo, are older feathers. The bird has therefore completed a partial moult which has included these feathers in its winter quarters, only Iberian Chiffchaff is known to do this. This would age the bird as in its first summer as adult Iberian Chiffchaffs moult all their primaries at the same time.

In Common Chiffchaff it is usual for all the primaries to be moulted together. Better photos, are needed to confirm this feature or actually trapping the bird. 

Primaries 7 and 8 look to have worn tips compared to primaries 1 to 6

Unfortunately the song is not typical of Iberian Chiffchaff although the notes that are present look to be typical of the notes used by Iberian Chiffchaff but there are notes missing from its typical song. The sonogram is shown below;

Sonogram for one 4 second phrase

I've posted a link to the sound recording below which should work if you use Google Chrome as your browser, I'm not sure about other browsers and you may need to download the sound file. 

Behaviour wise in addition to fluffing its breast and raising its rump feathers it does not flick the tail down as frequently as Common Chiffchaff.

It sings mostly high in the canopy but comes down to lower bushes to feed where it does short sallies for insects.

There are directions and further comments on the bird on Steve Mann's website.

I'm unable to embed the sound file so here is a link to it for now.

I'm happy to conclude that this bird is not Common Chiffchaff and its appearance is consitant with Iberian but I'm not sure about the song. It switches to a more Common Chiffchaff type song regularly although I have read that Iberian may do this.

Hybrids between the two species do occur and that must be a possibility although its appearance looks good for Iberian I think.

It's an interesting bird!

Hopefully the bird will remain for some time and we can confirm its identification.