Caspian (Eastern) Reed Warbler
Acrocephalus (scirpaceus) fuscus
Caspian Reed Warbler moults prior to the northward spring migration, unlike Eurasian Reed Warbler Acrocephalus (scirpaceus) scripaceus which moults on arrival in the wintering grounds.
Hence Caspian Reed Warbler is in fresher plumage during the northward migration, often showing obvious white tips to the primaries and pale edging to the remiges. It also shows blackish centres to the coverts, tertials and retrices, contrasting with the paler edges. It is similar to Marsh Warbler in these respects and can be quite a pitfall. But notice the brown and russet tones of the plumage, unlike Marsh Warbler which shows olive and yellow tones to the plumage.
One other observation is that fresh russet-brown Caspian Reed Warblers of the spring are very different to the worn grey birds of autumn which are often discussed - and occasionally encountered - in Western Europe.
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