Lined Seedeater

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Lined Seedeater

Quick Facts

Migratory
  • Scientific Name: Sporophila lineola
  • Spanish Name: Semillero listado
  • Family: Thraupidae
  • Known Nicknames: Lined Finch, Lined Seedeater
  • Average Length: 10–11 cm / 3.9–4.3 in
  • Average Weight: 9–12 g / 0.32–0.42 oz
  • Wingspan: N/A
  • Key Feature: Male has black crown, white supercilium, and black line through the eye; female is plain brownish.
  • Primary Diet: Granivore (primarily seeds)
  • Range: South America: eastern Bolivia, Paraguay, southern Brazil, Uruguay, and northern Argentina
  • Habitat: Grasslands, savannas, open areas with tall grass, and agricultural fields
  • Social Structure: Social; often seen in small flocks or mixed-species groups
  • Nesting/Breeding: Cup-shaped nest built in grasses or low shrubs
  • Conservation Status: Least Concern (LC)
  • Population Trend: Stable

The Lined Seedeater (*Sporophila lineola*) is a small, striking finch native to South America, renowned for its crisp, monochrome plumage and specialized seed-cracking bill. The male is unmistakable, with a brilliant white face, throat, and underbody sharply contrasted by a bold black cap, back, and wings, while females and juveniles are a warm, unstreaked brown. A unique feature is its remarkably thick, conical beak, perfectly adapted for husking tough grass seeds, and its habit of forming large, nomadic flocks that descend on bamboo and grass stands during the non-breeding season. This species also exhibits a distinctive, buzzy song, often delivered from an exposed perch, and its preference for savanna and agricultural edges makes it a lively, accessible bird for observers across its range from Panama to northern Argentina.

Fun Facts

The male Lined Seedeater undergoes a dramatic, almost magical transformation after breeding: it molts its striking black-and-white breeding plumage into a drab, sparrow-like brown, making it nearly indistinguishable from the female and juveniles—a rare example of "eclipse plumage" in a seedeater, likely to avoid predation while vulnerable during molt. During courtship, males perform a quirky "dance flight," where they hover in mid-air with rapid wingbeats while singing, often holding a single grass stem or leaf in their beak as a prop. Despite its delicate bill, this bird has a specialized jaw muscle that allows it to crack open tough grass seeds with surprising force, even those still encased in hard, spiky husks. In the wild, they form tight, nomadic flocks that can suddenly descend on a field of ripe grasses, strip it clean in minutes, and vanish just as quickly, a behavior known as "masting" that helps them exploit unpredictable food bonanzas.

Habitats & Distribution

The Lined Seedeater inhabits open and semi-open landscapes, primarily in lowland areas. It is typically found in tall grasslands, savannas with scattered shrubs, agricultural fields, plantations, and forest edges, often near water sources like rivers or marshes. It avoids dense, closed-canopy forests, favoring disturbed or transitional habitats where grass and weed seeds are abundant. Its geographical range spans central and eastern South America, including parts of Bolivia, Brazil, Paraguay, and northern Argentina. It also occurs as a non-breeding visitor in the Guianas and Venezuela, with some seasonal movements tied to food availability. Breeding populations are concentrated in the Cerrado and Pantanal regions of Brazil, extending into adjacent countries.

Behaviours & Reproduction

The lined seedeater exhibits a predominantly monogamous mating system during the breeding season, though males may engage in extra-pair copulations. Social structure is loosely colonial, with males defending small territories centered on a song perch and a preferred nest site. Males court females by singing and performing a fluttering display flight, often while carrying a piece of nesting material. The nest is a small, open cup woven from grass and rootlets, typically placed in a fork of a shrub or low tree. Females lay two to three eggs and handle most of the incubation, while both parents feed the chicks. A unique reproductive strategy involves the male’s intense defense of the nest area, often chasing away other seedeaters and even larger birds. The species is known to participate in mixed-species feeding flocks outside the breeding season, but pairs remain together for multiple broods within a single season if conditions are favorable.

Diet

The Lined Seedeater (Sporophila lineola) is a granivorous specialist, with its diet consisting almost entirely of grass seeds, particularly those from species in the Poaceae family. It forages predominantly on the ground or among low vegetation, often in small flocks, meticulously picking seeds from mature seed heads. An interesting fact is that its entire bill morphology is adapted for seed cracking; the upper mandible is slightly curved and fits tightly over the lower one, allowing it to efficiently hull even tiny, hard seeds. During the breeding season, adults may supplement their diet with soft-bodied insects or caterpillars to provide extra protein for their chicks, but seeds remain the overwhelming staple year-round.

Colors

The male Lined Seedeater is striking with a black head, white cheeks, and a white underbelly, contrasted by a bold black breast band and fine black streaking on its flanks. Its back and wings are dark gray to black with white wing bars, while the female is a plain, unstreaked olive-brown above and buff below, providing effective camouflage in grassy habitats.

Distribution Map

Places linked to this species. A sighting is never guaranteed.