The probable Iberian Chiffchaff (potentially a 1st for Pembrokeshire) was still at Pantmaenog this morning in pretty grim weather conditions!
Lisa and I watched it for around an hour 830-930. It was easy to locate by song - from the car park in Rosebush walk north past the disused quarries, past the house, and after crossing a gate (which is lowered in the middle for horses), bear right at the next fork. Go under the height restrictor, and about another 200m on a small track forks left and the bird was in hazel and small conifers here.
Much of the time the bird sings a classic Iberian Chiffchaff song in 3 clear parts, all completed in less than 4 seconds (we timed it). It would belt this out at least 8 times in a row. Then it would produce a Chiffchaff like 2 note song, but always short and of a faster tempo (again, less than 4 seconds).
We couldn't be 100% sure we heard it call. Iberian Chiffchaff sounds like a Siskin and there were several Siskins around to add to the confusion! However at one point we could hear the Siskin like call when we couldn't see a Siskin, and the bird in question was not singing so it may have been it calling.
In terms of plumage it looks spot on for Iberian, see The Collins Bird Guide for the main features. They are all present and correct.
So, it is either a genuine Iberian Chiffchaff, or it is a hybrid. The test is whether the range of song exhibited by this bird is within the tolerated range of Iberian. From the literature I have read so far, it would seem that it is.
Either way it's well worth a look!!