Gray's Grasshopper-warbler

Gray's grasshopper warbler is the largest of its relatives, nearly as big as the great reed warbler, 16.5–18 centimetres long. The adult has an unstreaked olive-brown back, a uniformly grey breast and a brownish underside with unspotted dull orange undertail coverts. The song is a loud, distinct, short, almost bulbul-like phrase, very unlike the insect-like song of the European Locustella species and more melodious than the sedge warbler's; during the breeding season it sings at dawn and dusk. (Swedish Wikipedia, general species account)

This East Asian warbler breeds in meadows in northeastern Asia and moves in winter to Southeast Asia; it has been found in Europe on only two occasions. It breeds in meadows in river valleys, forest edges, clearings and bamboo thickets, preferring tall herbs, nettle patches and overgrown ground, mainly in low-lying and coastal areas. It breeds from mid-June to early July, building a large, deep cup of dead leaves and dry grass on the ground among nettles, by a grass tussock or under a small bush, and the female lays three or four eggs incubated for about 15 days. (Swedish Wikipedia, general species account)