Common Grasshopper Warbler

The common grasshopper warbler is a medium-sized warbler 12.5–13 cm long and 11.5–16 g. The adult has a streaked brown back and whitish-grey underparts, unstreaked except on the undertail coverts, with pale olive-brown upperparts, each feather with a darker central streak, and slender pale yellowish-brown legs and feet. The sexes are identical, but young birds are yellower below. It breeds across much of temperate Europe and the western Palearctic (Wikipedia, general species account).

It is migratory, wintering across northern tropical Africa just south of the Sahara and locally in India, migrating south in autumn to the Sahel, India and Sri Lanka. The song that names it is a mechanical, grasshopper-like reeling, often at dawn or dusk, a long high-pitched trill delivered with the bill wide open and the whole body vibrating. It is secretive and hard to see, but easily detected by song. Both sexes build the nest. SoIB 2023 lists it as a winter migrant of grassland and scrub that eats invertebrates, without a priority category (Wikipedia, general species account; SoIB 2023).