Dark-throated Seedeater

The dark-throated seedeater is 10 to 11 cm (3.9 to 4.3 in) long and weighs 7 to 9.7 g (0.25 to 0.34 oz). It is one of the smallest of its genus. It has a smallish bill with a rounded culmen. The species is sexually dimorphic. Adult males have a gray crown and nape that give a "helmeted" appearance; the rest of their face is blackish brown. Their mantle and upper back are gray and their lower back and rump are rufous or dark cinnamon. Their tail is blackish with gray edges on the outer feathers. Their wings are blackish with gray-brown edges on the greater coverts and tertials. Their wing's primaries have white bases that show as a patch on the folded wing. Their throat and upper breast are blackish brown and the rest of their underparts rufous. Females have a mostly warm brown head with a buff face. Their upperparts are also warm brown and their tail is darker brown. Their wings are darker brown with sandy edges on the coverts and tertials and a small whitish primary patch like the male's. Their underparts are warm buff that is palest on the belly. Both sexes have a dark brown iris. Males have a dark gray to black bill and legs; females have a dark horn-colored to blackish bill and blackish legs. Juveniles resemble adult females.

In their 2025 versions AviList and the Clements taxonomy provide a detailed description of the dark-throated seedeater's range: "southeastern Bolivia (southeastern Tarija), southwestern Brazil (western Mato Grosso do Sul, southern Rio Grande do Sul), Paraguay, northern Argentina (Salta eastward to Corrientes, southward to Tucumán, northern Córdoba and northern Buenos Aires), and western Uruguay; non-breeding to northern and eastern Bolivia and central and southern Brazil (eastward to Minas Gerais, and southward to Rio Grande do Sul)". In addition, the South American Classification Committee has records of the species as a vagrant in Peru. The dark-throated seedeater inhabits tall grasslands, especially those long untouched by humans, and similar landscapes such as roadsides that have not been mowed. It is sometimes near damp areas but is less often connected to water than some others of its genus. In Argentina it also is found in scrubbier areas and in its non-breeding range in grassy Cerrado. In elevation it ranges from sea level to 1,200 m (3,900 ft).

The dark-throated seedeater feeds on grass seeds. It typically feeds while clinging to stems. It forages in small groups and often in larger ones that include other seed-eating species.