Tropeiro Seedeater is very similar to the widespread Plumbeous Seedeater (S. plumbea), but, in contrast, Tropeiro Seedeater has a very small breeding range and much more restricted habitat preferences. Tropeiro Seedeater breeds only in southern Brazil, from northeastern Paraná south to northeastern Rio Grande do Sul; and it winters (July to September) farther north, in eastern Goiás and western Minas Gerais. As a breeder, this species is confined to grasslands mixed with tall dense shrubs, associated with forests of Araucaria angustifolia. The male Tropeiro Seedeater is predominately gray; it is distinguished from male Plumbeous Seedeater by its yellow (not black) bill; more bluish gray tones to the plumage; and a different song. Females to the species are drab brown and much more similar to each other, but still can be separated by bill color. Tropeiro Seedeater may well be endangered: it is threatened by the loss of its grassland habitat throughout its range, and also by trapping for the cage bird trade.