Marsh warbler

The marsh warbler (Acrocephalus palustris) is similar in appearance to several other members of the warbler family, particularly the much more common reed warbler. It is widespread in continental Europe and Asia, although in the United Kingdom it is confined to the south-east of England, particularly Kent. It is a summer visitor, spending the winter months in East Africa.

The preferred habitat of the marsh warbler is dense vegetation close to rivers, and not necessarily marshes as might be assumed from its name. It can also be found in overgrown ditches and fields.

Appearance

The marsh warbler is about 12.5 centimetres long (5 inches). When compared with the reed warbler, it has a flatter crown, plumper body and longer wings, with pinkish legs. The upper plumage is olive-brown with the rump being yellower. The underparts are white and pale buff to yellow. Male and female marsh warblers are similar in appearance.

Behaviour

The song of the marsh warbler is particularly impressive and varied, and it can be heard at night as well as during the day. It is full of trills and “tweeks” and sometimes includes phrases mimicked from other birds.

The marsh warbler is less skulking in its behaviour than the reed warbler and will perch high in tall vegetation and trees.

The food of marsh warblers is insects, larvae and berries.

Breeding

Marsh warblers arrive in Europe and Britain as late as late May or early June. Nest-building takes place soon after arrival, consisting of grass and other plant stalks woven around the stems of nettles, reeds or similar plants. The nest is usually close to the ground and not far from running water, but never directly over it.

Only one brood will be raised in a season, the clutch comprising anything from four to seven eggs, although four or five is more usual. Both partners share the incubation duties for up to 13 days. The chicks leave the nest after some 12 or 13 days but will continue to be fed by their parents for some ten days more.

Marsh warblers return to their winter quarters in August or September.

© John Welford