© Copyright: Images: Jari Peltomäki, Jouko Lehmuskallio, M. & W. von Wright: Svenska fåglar (Kansalliskirjasto, The National Library of Finland). Recording: Jan-Erik Bruun. All rights reserved.
- Family: Reed warblers – Acrocephalidae
- Appearance: Common in reed beds. Upper parts olive brown with streaked patterning, except for unmarked reddish brown rump. Wide whitish eyebrow stripe distinctive.
- Size: Length 11.5–13 cm, weight 11–15 g.
- Nest: On the ground or low in vegetation, attached to plant stems. Made of sedge and reed leaves and aquatic moss, lined with hair and the soft heads of reeds.
- Breeding: 3–7 eggs laid in May–June, incubated mainly by female for 12–15 days. Fledglings leave nest within 10–16 days.
- Occurrence: Breeds in moist scrubland and reed beds throughout Finland. Breeding population estimated at 200,000–400,000 pairs.
- Migration: Nocturnal. Leaves Finland August–September, returning May–June after wintering in tropical Africa.
- Diet: Invertebrates.
- Calls: A clicking “chek” call. Song performed rapidly in reed beds sounds hectic and hurried.
Sedge Warblers can be distinguished from other warblers that breed in Finland by their reddish brown rumps, their broad off-white eyebrow stripes and the dark streaking on their backs. Adults’ underparts are off-white, with no streaking on their breasts. Juveniles in their first autumn have faintly speckled yellowish brown underparts. Sedge Warblers also have a fairly visible dark streak along their caps. Their legs are pale brownish grey, their beaks are black with a yellowish red base to the lower mandible, and their irises are brown.