Bay-capped Wren-Spinetail is occurs from extreme southern Brazil south through Uruguay to northern Argentina, south to northern Río Negro.
To date, no populations of banded individuals have been monitored year round to evaluate seasonal movements. Bay-capped Wren-Spinetail has been considered to be a resident in Buenos Aires province, Argentina (Narosky and Di Giacomo 1993), although seasonal changes in abundance suggest local movements (Cardoni et al. 2011). The majority of the members of the family Furnariidae are considered to be resident. Eleven species of furnariid are assumed to be long-distance migrants, although none abandon their entire breeding range during the nonbreeding season (Remsen 2003). Hence, if Bay-capped Wren-Spinetails do not remind in their breeding territories rear round, their migratory movements are likely to be short-distance.
Distribution outside the Americas
Endemic to South America.
Bay-capped Wren-Spinetail inhabit sedges and reedbeds in fresh, salt and brackish waters up to 900 m (Ridgely and Tudor 1994, Remsen 2003).
There is no information published on historical changes in the distribution of Bay-capped Wren-Spinetail. As an habitat specialist of fresh, brackish and salt marshes, its distribution may have changed through habitat transformation with reduction dew to drainage of marshes or expansion due to change in vegetation structure caused by sewage discharge.
The fossil record of the Furnariidae is very scarce and only four specimens from the Pleistocene have been reported, from the modern genera Cinclodes and Pseudoseisura and the fossil genus Pseudoseisuropsis (Remsen 2003). No fossils of the genus Spartonoica have been reported. Hence the taxonomic relationship with the other members of the family needs to be inferred from morphological, behavioral and molecular data.
Llambías, P. E. (2013). Bay-capped Wren-Spinetail (Spartonoica maluroides), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.bcwspi1.01