The Aquatic Warbler is by no means scarce in Europe, but is one of those south-eastern species that extend north-westwards through France and breed sparingly in Holland and Denmark. From recent observations it seems probable that a few examples regularly pass through this country on migration every autumn, but owing to its resemblance to the Sedge Warbler, it has probably often been overlooked.

In general colour it is lighter and paler than the Sedge Warbler, and the wing coverts have broad buffish margins. Its characteristic feature, however, is the conspicuous buff stripe down the middle of the crown. Length 4·9 in.; wing 2·4 in.