En bref

• Scientific Name: Amaurospiza moesta
• Spanish Name: Semillero azulnegro
• Famille : Thraupidae
• Known Nicknames: Blackish-blue Seedeater, Slaty Seedeater
• Longueur moyenne : 11–12 cm / 4,3–4,7 pouces
• Average Weight: 10–13 g / 0.35–0.46 oz
• Wingspan: 17–20 cm / 6.7–7.9 in
• Key Feature: Deep blackish-blue plumage in males, contrasting with a thick, conical grayish bill
• Primary Diet: Granivore (specialist on bamboo seeds)
• Range: South America: southeastern Brazil, eastern Paraguay, northeastern Argentina, and isolated populations in Bolivia
• Habitat: Bamboo thickets within Atlantic Forest and humid montane forest
• Social Structure: Semi-social; often seen in pairs or small family groups, sometimes joining mixed-species flocks
• Nesting/Breeding: Cup-shaped nest built in bamboo or dense shrubs
• Statut de conservation : Quasi menacé (NT)
• Évolution démographique : En baisse

The Blackish-blue Seedeater (*Amaurospiza moesta*) is a strikingly elusive songbird of the Andes, with a unique, gender-specific beauty that sets it apart from typical seedeaters. Males are cloaked in a deep, glossy blackish-blue plumage that can appear nearly black in low light but shimmers with a subtle indigo sheen, while females are a warm, rich cinnamon-brown, offering excellent camouflage in the dense bamboo thickets they call home. Its most special feature is its massive, conical silver-gray bill, disproportionately large for its small body, perfectly adapted for cracking open the tough seeds of its preferred *Chusquea* bamboo. Unlike many finches that flock in open fields, this shy species clings to the shadows of montane forests, its presence often betrayed only by a sharp, metallic *tink* call, making it a coveted sighting for birdwatchers due to its specialized habitat and secretive nature.

Faits amusants

Despite its name, the Blackish-blue Seedeater isn’t always blackish-blue; males undergo a dramatic seasonal molt, turning a dull, brownish-gray during the non-breeding season, essentially becoming unrecognizable from their brilliant breeding plumage. It has a bizarre, almost comical feeding habit of clinging upside-down to bamboo stalks like a tiny acrobat, using its stout, conical bill to expertly pry open bamboo seeds—a near-exclusive diet that makes it a specialist dependent on bamboo flowering cycles. Furthermore, its song is surprisingly weak and insect-like for a bird of its size, often described as a thin, high-pitched “tzee-tzee-tzee” that seems far too delicate for a bird that can be so boldly colored.

Habitats et répartition

The Blackish-blue Seedeater is primarily found in the Atlantic Forest biome of southeastern South America. Its habitat consists of dense, humid montane and submontane forests, often near bamboo thickets, which are a key component of its ecology for both feeding and nesting. The species has a fragmented distribution, ranging from eastern Paraguay and northeastern Argentina (Misiones province) into southeastern Brazil, with records extending from the states of Minas Gerais and Rio de Janeiro south to Rio Grande do Sul. It typically occurs at elevations between 500 and 1,800 meters, favoring forest interiors and edges with abundant understory vegetation.

Comportements & Reproduction

The Blackish-blue Seedeater is generally solitary or found in pairs, with a social structure centered around mated couples defending a small territory during the breeding season. Mating is monogamous, and courtship involves the male performing a fluttering display flight while singing from a prominent perch to attract a female. The female builds a compact, cup-shaped nest woven from grass and rootlets, typically placed in a dense shrub or bamboo thicket near water. She lays two to three pale blue eggs with speckling, and incubation is performed solely by the female for about 13 days. A unique reproductive strategy is their strong association with bamboo forests; breeding often synchronizes with bamboo seeding events, providing an abundant food source for chicks, though this can be unpredictable. Both parents feed the young, which fledge after roughly two weeks, and pairs may raise one or two broods per season if conditions are favorable.

Alimentation

The Blackish-blue Seedeater (Amaurospiza moesta) is a specialist granivore, with its diet consisting almost entirely of bamboo seeds, particularly from species in the genus *Chusquea* and *Guadua*. This extreme dietary specialization ties its survival directly to the irregular, mass-flowering and seeding cycles of bamboo, which can occur only once every several decades. During these boom periods, the seedeater gorges on the abundant, high-energy seeds, but between these events, it must supplement its diet with small amounts of other grass seeds, buds, and occasionally small insects or berries to survive. Interestingly, this species is known to follow bamboo die-offs and regeneration, migrating locally to seek out new patches of flowering bamboo, a behavior that makes it highly nomadic and vulnerable to habitat fragmentation.

Couleurs

The male Blackish-blue Seedeater is a deep, slaty blue-black overall, appearing nearly black in low light, with a subtle blue sheen on the wings and tail. The female is a warm, rich cinnamon-brown above and paler buff below, lacking any bold markings or streaks. Both sexes have a stout, conical silver-gray bill. This uniform, dark coloration likely serves as camouflage in the dense, shaded understory of bamboo and forest edges where it forages.

Distribution Map

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

Détails de l'attraction

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