The Common Reed Warbler (Acrocephalus scirpaceus) is the unassuming brown warbler of the reed bed, heard far more often than it is seen as it delivers its monotonous, rhythmic song deep within the reeds. It is a small, slender passerine measuring 12–14 cm in length, with a wingspan of about 17–21 cm and a weight of only 10–15 grams. The plumage is discreet and lacks clear markings: the upperside is uniformly olive-brown with a slightly warmer tone toward the rump, and the underside pale beige, while the eyebrow stripe is faint and the bill fine and pointed. This uniform, unstreaked plumage is what separates it from the streaked-backed Sedge Warbler.
The song is characteristically monotonous and rhythmic, a persistent series of repeated, somewhat scratchy phrases often rendered "tjerr-tjerr-tjiri-tjiri-tjerr," delivered at a steady, almost leisurely pace quite unlike the more varied, improvising songs of several relatives; the call is a short, hard "tjeck." The Common Reed Warbler breeds in southern and central Sweden, mainly around lakes and sea bays with large reed stands, with a population of 20,000–40,000 pairs; it is classed as Near Threatened on the Swedish red list, partly due to declining and degraded reed habitats. It is a long-distance migrant that arrives late, at the end of May, and leaves in August to winter in sub-Saharan Africa. It builds an elaborate, deep, cylindrical nest woven tightly between several reed stems just above the water surface, laying a usual clutch of 3–5 eggs, and is a common host for the Cuckoo, which lays its eggs in reed warbler nests so that the much smaller host ends up raising the far larger cuckoo chick. The diet is almost entirely insects and other invertebrates picked among the reed stems and leaves, caught both while perched and during short sallies.
Read about this species in Swedish →