Bay-capped Wren-Spinetail

Overview

The bay-capped wren-spinetail, Spartonoica maluroides, is a small bird in the ovenbird family Furnariidae. It is the only member of its genus and is found in southern South America, including parts of Brazil, Uruguay, and Argentina. The species is currently classified as Least Concern by the IUCN, though its population is believed to be decreasing.

Identification

• Size is between 13 and 14.5 cm long with a weight of approximately 10.5 g.
• Adults feature a rufous crown and a whitish supercilium on a sandy brown face, with bold black streaks on the nape and upper back.
• Underparts are whitish with a buff or cinnamon tinge on the breast, sides, and flanks; the bill is blackish above and whitish to pinkish below with a dark tip.
• The primary song is described as a grasshopper-like buzz that is long, tuneless, and rises and falls.

Habitat

This species inhabits reedbeds and sedges in freshwater, brackish, and saltwater marshes, ranging in elevation from sea level to about 900 m. Its range extends from extreme southern Brazil through Uruguay into northern Argentina, as far south as Río Negro Province, with occasional non-breeding presence in Paraguay.

Diet

The bird feeds on invertebrates, mostly insects and spiders. It usually forages alone by gleaning from marsh grasses and sedges, with pairs nesting in salt marshes sometimes preferring to feed in freshwater marshes.

Did you know?

Uniquely among furnariids, this species builds an open cup nest of twigs and grass placed low to the ground deep inside marsh vegetation, rather than a closed enclosed structure.