Many thanks to Dr J. Martin Collinson for the DNA analysis and speedy result of the interesting Chiffchaff caught and ringed at Wintersett on 20.05.17.
Here's the reply:-
"Your Chiffie (Wintersett Res, 20 May 2017 – our ref CC211) came in just as we were doing a batch of chiffies so we were able to do it straight away. I’m afraid its cytb sequence was nominate collybita rather than ibericus. Of course that doesn’t rule out a hybrid, but if it seems the in hand criteria need tweaking I’ll happily contribute to writing this bird up."
Here are the pictures showing the Chiffchaff with many of the 'ibericus' features. + comments made at the time.
Comment by GJ Speight
strikingly long bill with all yellowish under mandible
lack of a pale eyering
bright yellow soles to feet
lemony wash to vent
can't see the rump but it ought to be slightly brighter than the rest of the upperparts
these are all pro Iberian features.
Comment by P Smith
Also note the long supercilium being bright yellow and broad in front of the eye. Another good feature of Iberian Chiffchaff.