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. THE GRASSHOPPER WARBLER Locustella nævia (Boddært) Though never very abundant, this skulking species is commoner than is usually supposed. Arriving towards the end of April, its peculiar trilling song, which has earned it many local names, may often be heard. It sounds, however, so much like the noise made by a grasshopper that the bird is frequently unrecognised. This species is rarely seen, for it loves to remain concealed in the thick undergrowth, either in a compact hedge or in large stretches of sedge and rough grass, but, if we trouble to trace it by its song, we may be lucky enough to see a dark bird moving near the ground with hesitating flight. As it drops after a very short journey into the cover again, we may have time to notice the rounded tail, which is always spread as it settles and is the best clue by which to identify this species on the wing. Approach the spot where he disappeared and you will search in vain, for he has already crept away, and in a few minutes the song will recommence several yards off. As with all the Warblers, insects form their chief food. The nest, built of grass and bents loosely woven together, is placed low down and well concealed in the rough herbage near the ground, and as the bird seldom flies from it, but creeps silently away on our approach, it is exceedingly difficult to find. Six eggs form the clutch; the ground colour is whitish, but they are very thickly and uniformly mottled and freckled with reddish brown. The general colour above is greenish brown, each feather having a darker centre. Wings and tail brown, the latter showing faint bars. Under parts brownish, slightly spotted on the throat and breast, darker on the flanks and paler on the belly. The sexes are alike in plumage. Length 5·4 in.; wing 2·4 in. SAVI’S WARBLER Locustella luscinioides (Savi)