The yellow-chinned spinetail is typically 15 cm long, and weighs 15 g. It is a slender bird with a long tail. The upperparts and head are chestnut brown, and the underparts are whitish apart from the pale yellow throat. The sexes are similar, but there are several subspecies, differing in forecrown colour or upperparts tone. Its call is a shrill rattling.
Range and ecology
The yellow-chinned spinetail is found in all contiguousregions of Brazil, except specific parts of the Amazon Basin. In northern South America, the species is mainly found along the coast, in a continuous coastal strip that extends from the mouth of the Amazon River's mouth through northern Brazil's Amapá state, the Guianas - extending to the headwaters of the south-flowing Branco River in the north central of Brazil's Roraima state as it borders the Guiana Highlands -, Venezuela, where its range extends more widely inland along the Orinoco River, to northern Colombia where it ranges up the Madeira River valley beyond the Serranía de las Quinchas. Further south, like its sister species, the red-and-white spinetail it is found along the Amazon Rivercorridor. From the upper Amazon exiting the Andes, it only occurs in the river corridor, then up the Madeira River, southwestwards into Bolivia. From there, it ranges along the Andean foothills to northwestern Argentina, Paraguay and Uruguay and finally the Rio de la Plata. It is apparently absent from much of Pará and northern Mato Grosso states, essentially between the Madeira and Araguaia River corridors. But apart from that region it occurs in most of South America in the area enclosed by - running counterclockwise - the lower Amazon and the Madeira river, the Andes, the Paraguay and lower Paraná rivers, and the Atlantic Ocean. This species is a common resident breeder in marshes and the edges of mangrove swamps; in general its habitat is open woodland in the vicinity of rivers. The yellow-chinned spinetail feeds on insects and spiders, keeping low and often in the open. It is a conspicuous, confiding and noisy bird. Unlike the related ovenbirds, the yellow-chinned spinetail constructs a large spherical stick nest, usually low in a mangrove or other marsh vegetation. The tubular entrance tunnel rises almost vertically from the base to the top of the nest. The normal clutch is three, sometimes four, greenish white eggs. This spinetail is parasitised by the striped cuckoo, which lays one or two eggs in the nest, but it is not known how the cuckoo enters the nest or whether it or its offspring eject the host's young. This widely ranging bird is not considered threatened by the IUCN.
