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Grass Wren | Cistothorus platensis
Graswinterkoning | Chivirín sabanero | Corruíra-do-campo
The Grass Wren is a small, streaked wren of tall grass and rank grassland, in the guide area mainly in the páramo and humid puna of the Andes. It lives hidden low in the vegetation, but males sing from grass stems and low shrubs. The species is widespread in the Americas and geographically very variable; it probably comprises several species.
Voice
The song is a repeated series of dry ticks and short, clear or grating trills, which differs strongly from region to region; a singer often alternates between different phrases. The call is a dry chip or a short rattle.
Recording: Juan Freile — CC BY-NC-SA 4.0 · xeno-canto
Identification
10–11 cm, with a short, thin bill and a short tail that is often held cocked. The crown is black with pale streaks, the back black with white and buff streaks. The supercilium is narrow and buffy. The wings and tail are brown with dark barring. The underparts are buff, with a paler throat and warmer cinnamon flanks. The sexes are alike; young birds are less sharply streaked.
Confusion species
Apolinar's Wren Cistothorus apolinari is larger and longer-tailed, with an unstreaked brown crown, a greyish supercilium and greyer underparts, and lives in reeds in the Eastern Andes of Colombia. Southern House Wren Troglodytes musculus has an unstreaked brown back and lives in open, often inhabited areas. Santa Marta Wren Troglodytes monticola has an unstreaked grey-brown back and white underparts.
Habitat
Humid tall grassland, páramo with tussocks and low shrubs, the edges of bogs and marshes and grassy slopes in the Andes, mostly between 2500 and 4500 m; in Bolivia also in wet lowland savannas. It eats insects and spiders, which it seeks low in the grass. The nest is a domed structure of grass with a side entrance, low in a grass tussock.
Where the bird is most at home, classified by the vegetation units of the Andes and the west coast.
Range and movements
In Colombia in the Andes, mainly in the páramo of the Eastern and Central Andes. In Ecuador in the páramo and high grassland of the Andes. In Peru in the Andes, in humid grassland and puna. In Bolivia in the Andes and locally in the lowland savannas of the north and east. Absent from the Galápagos. Outside the guide area from Mexico to Panama, in Venezuela and the Guianas, and from Brazil to Argentina, Chile and the Falkland Islands.
- Resident
- dark = core range, pale = thinly spread
How and when to look
In the early morning in páramo and humid grassland with tall tussocks; singing males then perch on a stem or small shrub. After hearing it, wait quietly, as the bird often comes up briefly.
Conservation status
Least Concern. Locally, suitable grassland is lost to burning, intensive grazing and conversion to fields and tree plantations.
Scientific name
Cistothorus platensis | (Latham, 1790)
Latham described the species in 1790 as Sylvia platensis; because it was later moved to another genus, the author and year stand in brackets. The genus Cistothorus was introduced in 1851 by Cabanis. The genus name comes from Greek kistos, 'bush', and thouros, 'leaping, running through'. The species name refers to the Río de la Plata region, not necessarily the type locality. The specimen the first description was based on came from Buenos Aires, Argentina.