Marsh Warbler

Marsh Warbler, Acrocephalus palustris, is an Old World warbler in the genus Acrocephalus. It breeds in temperate Europe and western Asia. It is migratory, wintering in south east Africa. It does not breed in Iberia, and in England it is scarce and declining, with the former main centre of population in Worcestershire now extinct.

This small passerine bird is a species found in fairly tall rank vegetation in marshes or by rivers. 3-6 eggs are laid in a nest in reeds or low vegetation.

This is a medium-sized warbler. The adult has a plain brown back and pale underparts. It can be confused with Reed Warbler, but is greyer on the back, the forehead is less flattened and the bill is less strong and pointed. The sexes are identical, as with most warblers, but young birds are yellower below.

The habitat is different from the reed beds favoured by Reed Warbler. Like most warblers, Marsh Warbler is insectivorous, but will take other small food items including berries.

In the breeding season, the best identification feature is the song, which is high and fast, and consists almost entirely of mimicry of other birds, punctuated with typically acrocephaline sqeaks and whistles. Dozens of different European and African bird calls have been identified in the song of this warbler.