About Herpsilochmus longirostris Pelzeln, 1868
The large-billed antwren (Herpsilochmus longirostris Pelzeln, 1868) measures 12 to 13 cm (4.7 to 5.1 in) in length and weighs 12 to 14 g (0.42 to 0.49 oz). As suggested by its English common name and specific scientific epithet, its bill is heavier than the bills of most other Herpsilochmus antwrens. Adult males have a black crown and nape, a long whitish supercilium, a narrow black streak running through the eye, and grayish ear coverts. Their back and rump are gray, with a black and white patch between the scapulars and black uppertail coverts tipped with white. Their wings are black, with white-tipped coverts and flight feathers that have white edges toward the feather ends. Their innermost tail feathers are black with white edges, the outermost tail feathers are entirely white, and the intermediate tail feathers are black with white tips. Their throat and underparts are mostly white, with tiny black spots on the sides of the breast and grayish sides and flanks. Adult females have a rufous-cinnamon crown, cinnamon-tinged gray ear coverts and upperparts, and cinnamon coloring on the neck, throat, and underparts. Their wings and tail match the coloring and patterning of males. The large-billed antwren is found south of most of Amazonia. It occurs in the northern parts of Bolivia's Beni and Santa Cruz departments, and in south-central to northeastern Brazil. In Brazil, its range is roughly bounded by the states of Mato Grosso, Tocantins, and Paraná, though it occurs locally as far northeast as southern Ceará and Piauí. It inhabits deciduous and semi-deciduous forest, gallery forest, and palm groves, and does not favor any particular vertical level within the forest. In Bolivia, it also often inhabits small patches of forest within otherwise open cerrado. Its elevation range is approximately 150 to 1,100 m (500 to 3,600 ft).
