Lesser Grass-Finch

The lesser grass finch is 18 to 20 cm (7.1 to 7.9 in) long and weighs 18.5 to 22 g (0.65 to 0.78 oz). It has a long pointed tail and a moderately thick bill. The sexes have the same plumage. Adults have a greenish to brownish crown with thin blackish streaks. They have a mostly grayish face with darker lores, a pale supercilium, and a thin whitish eye-ring. Their nape is gray. Their upperparts are boldly streaked with greenish brown and black; the black streaks are thinner on the rump and uppertail coverts. Their wings are mostly brownish with wide bright green edges. Their tail feathers have dark centers and grayish brown edges. Their throat is white and their underparts mostly pale grayish white. Their flanks are buff and they and the vent area have darker streaks. They have a dark brown iris, a yellow-orange bill with a blackish culmen, and brownish yellow to dull pinkish legs feet. Juveniles are similar to adults with the addition of a buffy yellow cast to the upperparts, a yellow cast to the face and underparts, and streaks on the breast.

The lesser grass finch has a "U" shaped range from eastern Paraguay south into northeastern Argentina to Entre Ríos Province, across northeastern Argentina and northern Uruguay, and north in southeastern Brazil through Rio Grande do Sul to far southern Minas Gerais. It primarily inhabits wet grasslands, swampy meadows, and marshes. It less frequently occurs in drier grasslands. In elevation it ranges from sea level to 900 m (3,000 ft).

The lesser grass finch's diet has not been studied. Single individuals and pairs forage on the ground, usually somewhat concealed in grass.