Before this year, my experience of calling Pallas's was limited to three birds (of five seen) in autumn/early winter 2003, and all gave the rather distinctive calls as can be heard on the excellent 'Calls of Eastern Vagrants' CD and elsewhere, but I must admit, having thought that I had 'come to grips' with their vocalisations, to being somewhat thrown this October.
After having great views of my first Dusky Warbler there on 22nd October, I decided to avail of a lift and go back to Ballycotton again on the 23rd. The Dusky was obliging again, and, while looking at that, I got word that a Pallas's Warbler had been found elsewhere in the village, so we decided to look for that. The bird was elusive at first, and initial views were a piece at a time: some 'normal' calls were heard around then.
A while later, after much of the 'crowd' had thinned, I heard a call from some bushes that I would have likened to that given by some eastern Chiffchaffs (similar to that listed as 'eastern abietinus' on the 'Eastern Vagrants' CD), so imagine my surprise when, on looking in the direction from whence the calls came, I was confronted not with a dull Chiffchaff, but the Pallas's! We then went on to get excellent views of this gem of a bird.
Now, the bird had been heard in song earlier (presumed subsong?), so perhaps this 'call' was related to that, or perhaps the species regularly gives more than one call type? Some calls on recordings that I've heard do sound less distinctive than others, though none quite sounded like this one.