Extreme south-eastern Brazil (Rio Grande do Sul), Uruguay and extreme eastern Argentina (Entre Ríos, northern Buenos Aires).
 
Population
Estimated population is unknown (2010) and decreasing.
Status NT
Habitat destructiuon and degradation through house-building, rubbish dumps and water pollution, intensive grazing, marsh drainage, extensive willow Salix plantations and the drying effects of Eucalyptus and Pinus spp. plantations, are the main threats.
For more information see BirdLife International Species Factsheet.
Voice
A series of high-pitched notes accelerating into a trill.
Straight-billed Reedhaunter (Limnoctites rectirostris) [XC225139]
by Fernando Jacobs from Aparados da Serra, Rio Grande do Sul, Brazil (song)
Straight-billed Reedhaunter (Limnoctites rectirostris) [XC22306]
by Enric Fontcuberta from RPPN Pontal da Barra - Pelotas, Rio Grande do Sul, Brazil (song)
Subspecies
No subspecies.
No obvious close relatives. Placed by some authors in genus Limnornis, whereas others do not consider the two genera closely related. Differs strongly from that taxon in tail structure, nest materials used, and white egg colour.
Similar Species
The more widespread Curve-billed Reedhaunter (Limnornis curvirostris) is stockier and has a curved bill, it is brown above not greyish and with a shorter, broader and rounder tail which lacks the protruding spines.
References
See References.