(hippolais pallida)
The Eastern Olivaceous Warbler is a very rare vagrant to Scotland. Up to the publication of Birds of Scotland Edition 3 there had only been four records. It is a very common bird in the Balkans and through Turkey and the Middle East, normally wintering south of the Sahara. Around my usual summer holiday spot of Dalyan in Turkey it is one of the commonest birds with the bird's chacking call being heard all over the place even in gardens in the town centre.
See https://pbase.com/ianfulton/turk_olivaceouswarbler for photos of this species from Dalyan.
This species has suffered some name changes. Formerly there was a species called Olivaceous Warbler which was split into Eastern Olivaceous Warbler and Western Olivaceous Warbler. Then later Western Olivaceous Warbler was renamed to Isabelline Warbler so now this Eastern Olivaceous Warbler is sometimes simply called Olivaceous Warbler. Confusing !
The bird photographed here was discovered in the scrubby bushes at Kilminning close to Fife Ness and proved to be a very popular twitch and a welcome addition to many UK birder's list.