Family Grasshopper-warblers and Grassbirds (Locustellidae)

Near Threatened

Marsh Grassbird (Locustella pryeri)


French: Locustelle du Japon German: Riedschwirl Spanish: Yerbera japonesa
Other common names: Japanese Swamp Warbler

Megalurus pryeri


, 1884,

Tokyo, Japan


Previously placed in Megalurus, but morphological features (bill and foot structure, length of undertail-coverts, wing formula) and molecular data place it within Locustella#R#R. Race sinensis suggested as perhaps a separate species, but although it is whitish vs pale grey from throat to belly (1), with less extensive and paler rufous flanks (2) and paler upperparts (1), the voices are near-identical. Two subspecies recognized.

What do (1) and (2) mean? Learn more about the scoring system.
Subspecies and Distribution
  • L. p. sinensis (Witherby, 1912) – Chinese Grassbird – locally in extreme E Mongolia, E China (Inner Mongolia, Heilongjiang, Liaoning, Hebei and Shanghai) and extreme SE Russia (L Khanka, in Primorskiy); non-breeding SE China (basin of lower R Chiang Jiang in S Hubei, N Hunan and N Jiangxi).
  • L. p. pryeri (Seebohm, 1884) – Japanese Grassbird – C Japan (N & E Honshu); non-breeding S to Shikoku.
  • Descriptive notes

    12–14 cm; 11·1–17·2 g (nominate), 10·4 g (sinensis). A medium-sized warbler with boldly streaked upperparts; rather long and “... read more


    Song, from prominent tall reed and in air, a low-pitched, repeated “djuk-djuk-djuk”;... read more


    Breeds in wet reed-swamp. In Japan, in particular by shallow lakes where extensive beds of sedges... read more

    Food and feeding

    Food consists almost entirely of small insects, chiefly larvae of moths (Lepidoptera) and flies (Diptera), which especially important food... read more


    Begins at start of rainy season (c. 20th Jun), chicks generally fledging between mid-Jul and mid-Aug, in Japan; carrying nest material in... read more


    Japanese race (nominate) partially migratory, present in N Honshu from early May to Oct, moving to... read more

    Status and conservation

    Not globally threatened. Currently considered Near Threatened, and previously, Vulnerable. Rare and very local. Extremely skulking when not singing; as a result, passage... read more

    Recommended citation

    Madge, S. (2020). Marsh Grassbird (Locustella pryeri). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from on 23 February 2020).