Tropeiro Seedeater

The Tropeiro seedeater averages 11.8 cm (4.6 in) ± 1.95 cm (0.77 in) long. It weighs an average of 11.8 g (0.42 oz) ± 1.01 g (0.036 oz). It has a thick bill with a rounded culmen. The species is sexually dimorphic. Adult males have a lead-gray head with a pale arc under the eye and some faint darker streaks on the crown. Their upperparts are lead-gray with a bluish cast on the mantle and scapulars, and with faint darker streaks except on the rump. Their tail is blackish with very thin grayish olive edges and buffy tips on the feathers. Their wings' upper sides are blackish with olive-gray edges on the coverts, olive-brown edges on the tertials, and white bases on the primaries that show as a small square on the closed wing. Their chin and lower cheek are at most very slightly whitish, their throat and breast a medium gray with a bluish cast, and their belly and undertail coverts whitish. Their wings' undersides are gray with white marginal coverts. Adult females have a brownish olive to olive-green head, upperparts, tail, and wings without the male's white primaries. Their chin, throat, belly, and vent are whitish and their breast and flanks drab gray with a buffy brown wash. Both sexes have a dark iris and lead-gray to black legs. Males have a bright yellow bill and females a brown maxilla and a paler yellowish mandible. …

The Tropeiro seedeater is found in southeastern Brazil from far northeastern Rio Grande do Sul north to northeastern Goiás, northwestern Minas Gerais, and far southwestern Bahia. It breeds in a relatively narrow strip between Rio Grande do Sul and northeastern Paraná, overwinters in Goiás, Minas Gerais, and Bahia, and migrates between the two. The "borders" between breeding area and the migratory path and between the migratory path and the wintering area are not sharp lines. The Tropeiro seedeater "is highly specific in habitat use, breeding in grasslands with dense tall shrubs associated with Araucaria angustifolia forests". It nests on steep hillsides in a narrow elevational range between 650 and 950 m (2,100 and 3,100 ft) above sea level. Its distribution in the breeding zone "is very fragmented, in accordance with the patchy nature of its habitat". The plumbeous seedeater breeds at higher elevations in flatter landscapes that have shorter and more widely spaced shrubs. The Tropeiro seedeater winters in cerrado savanna and similar landscapes with tall grass.

The Tropeiro seedeater's diet and feeding behavior have not been studied. It has been seen feeding on the seeds of purple speargrass (Piptochaetium stipoides) while clinging to the stems.