Great Reed Warbler

The Great Reed Warbler, Acrocephalus arundinaceus, is a robust, thrush-sized member of the Acrocephalidae family. It is the largest of the European warblers, measuring 16–21 cm in length with a wingspan of 25 to 30 cm and weighing between 22 to 38 g. The adult is characterized by unstreaked brown upperparts and a dull buffish-white underbelly. A distinctive feature is its flattened forehead and strong, pointed bill. It bears a striking resemblance to the Eurasian Reed Warbler, albeit significantly larger in size.

Identification Tips

When identifying the Great Reed Warbler, look for its strong supercilium and the lack of streaking on its brown upperparts. The chin and underparts are buffish-white. Both sexes appear similar, with young birds presenting a richer buff on the underparts. Its size, akin to that of a thrush, sets it apart from other warblers.

Habitat

During the breeding season, this species shows a strong preference for large reed beds, often with interspersed bushes. In winter, it can be found in a variety of habitats including reed beds, bush thickets, rice fields, and forest clearings.

Distribution

The Great Reed Warbler breeds across mainland Europe and the western Palearctic, with its range extending to sub-Saharan Africa during the winter months. It is a migratory species, with some populations showing distinct migratory routes and wintering grounds.

Behaviour

This bird is territorial on its breeding grounds but may form large groups in winter, often dominating reed beds to the exclusion of other species. It is primarily insectivorous, though its diet can include other small prey such as tadpoles.

Song & Calls

The Great Reed Warbler's song is loud and carries far. The main phrase of its song is a chattering and creaking "carr-carr-cree-cree-cree-jet-jet," embellished with whistles and vocal mimicry typical of marsh warblers.

Breeding

Breeding pairs may be monogamous or polygynous. Females lay 3–6 eggs in an open cup-nest within the reeds. Some males, known as "satellite" males, may father offspring despite not being paired.

Similar Species

The Great Reed Warbler can be confused with the Eurasian Reed Warbler (A. scirpaceus), but it is significantly larger and has a stronger supercilium.

Diet and Feeding

The diet of the Great Reed Warbler is carnivorous, consisting mainly of insect larvae, moths, dragonflies, damselflies, beetles, spiders, small fish, and frogs. During the non-breeding season, it may also consume fruit.

Conservation Status

The IUCN lists the Great Reed Warbler as a species of Least Concern. It experiences marked long-term population fluctuations and can rapidly expand its range when new habitats become available.