The aquatic warbler is an Old World warbler in the genus Acrocephalus. It breeds in temperate eastern Europe and western Asia, with an estimated population of 11,000-15,000 pairs. It is migratory, wintering in west Africa. After many years of uncertainty, the wintering grounds of much of the European population were finally discovered in Djoudj National Bird Sanctuary, Senegal, with between 5,000 and 10,000 birds present at this single site. Its south-westerly migration route means that it is regular on passage as far west as Great Britain and Ireland.
Region
Eastern Europe and western Sahel
Typical Environment
Breeds in lowland sedge fens and wet peat mires across eastern Europe, with strongholds in Belarus, Poland, Ukraine, and Lithuania. It favors extensive open stands of tall sedges (Carex) with shallow, stable water tables and minimal reed dominance. During migration it uses wet meadows, marsh edges, and coastal marshes as stopover sites across central and western Europe. In winter it occupies seasonally flooded grasslands, brackish marshes, and river floodplains in the western Sahel, especially Senegal and adjacent countries. Habitat quality is tightly linked to water management and late-season mowing.
Altitude Range
0–300 m
Climate Zone
Temperate
Ease of Keeping
Beginner friendly: 1/5
The aquatic warbler is Europe’s only globally threatened passerine, highly dependent on open sedge fens kept wet year-round. It requires traditional mowing or grazing to prevent shrub encroachment, making it a flagship for wetland management. Large numbers winter in the western Sahel, with key sites such as Djoudj National Bird Sanctuary in Senegal. International conservation projects track its long south‑westerly migration and restore its breeding mires.
Acrocephalus paludicola - MHNT
Translocated aquatic warbler chicks in June 2018.
Chicks from the first translocation of the aquatic warbler in June 2018.
Temperament
secretive and skulking
Flight Pattern
short rapid wingbeats, low over vegetation
Social Behavior
Typically solitary or in loose proximity during breeding, with males singing from sedge tussocks. Nests are woven low in sedge clumps just above water; females primarily handle incubation and chick rearing. Clutches usually contain 4–5 eggs. Outside the breeding season, small flocks may form at rich feeding sites.
Migratory Pattern
Seasonal migrant
Song Description
A rapid, scratchy series of rattling trills and buzzy phrases, more rhythmic and repetitive than the Sedge Warbler. Phrases are delivered from exposed song posts, often at dawn and dusk, with brief pauses between strophes.
Plumage
Upperparts warm brown with strong blackish streaking and a distinct pale central crown stripe; underparts buff with fine streaks on the breast and flanks. Wings show dark centers with paler fringes; rump not strongly rufous. Overall more heavily streaked and buff-toned than the similar Sedge Warbler.
Diet
Feeds mainly on insects and other small invertebrates, including beetles, flies, moths, spiders, and larvae. Prey is gleaned from sedge stems and leaves or picked from the water surface and mud. It occasionally makes short sallies to snatch flying insects. During migration and winter it continues to take small aquatic and terrestrial invertebrates in flooded grasslands.
Preferred Environment
Forages within dense sedge beds and wet meadows, often just above shallow water. Uses edges of pools, ditches, and tussocks where invertebrate densities are high. In winter it concentrates in seasonally inundated plains and brackish marsh mosaics.
