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Tropeiro Seedeater Sporophila beltoni Scientific name definitions

Josep del Hoyo, Nigel Collar, and Guy M. Kirwan
Version: 1.0 — Published March 4, 2020
Text last updated September 22, 2019

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Originally Appeared in

HBW Alive

Field Identification

11–12·6 cm; mean 12 g (male) or 11·8 g (female). Tiny passerine with thick bill that is higher, wider and longer than that of formerly conspecific S. plumbea. Male is lead-grey above with bluish cast to mantle and scapulars, pale lower half of eyering, indistinct streaking on crown and upperparts (except rump); tail feathers blackish, very narrow greyish-olive fringes and warmer buffy tips; upperwing blackish, upperwing-coverts and tertials edged olive-grey (more olive-brown on tertials), primaries with well-demarcated white bases (on folded wing forming small square-shaped white panel not extending to outer two primaries); chin and base of malar tract can whitish, but are more usually grey and if whitish they are never contrasting; mid-grey throat and breast (with a bluish-grey tone), becoming whitish on belly to undertail-coverts; underwing grey, whitish linings; iris dark; bill bright yellow, and legs lead-grey to black. Female is typical of genus, dull and nondescript, lacking any distinctive features, brownish olive to olive-green above and drab grey infused buffy brown below, becoming whitish on chin, throat, belly and vent; iris brown, bill brown with paler yellowish mandible or base of it, and legs reddish black. Juvenile is like female, but bill can be jet-black and never shows any contrast between mandible and maxilla, and is sexually mature at c. 12 months; immature male is drab grey above with a whitish belly and flanks contrasting with drab buff breast, and acquires yellow bill by 24 months; subsequently, prior to acquiring fully adult plumage when four years old, male is rather dull grey, with variable drab vestiges of body plumage, tertials drab on distal edge and blackish on proximal edge, and can occasionally retain some dark elements within the yellow of bill; young female starts to acquire a yellow base to mandible after 12 months, sometimes even an all-yellow bill by three years old.

Systematics History

Yellow-billed birds found in extreme S range of (and otherwise largely resembling) S. plumbea have been assigned to that species for the best part of two centuries, but were recently shown to represent a distinct species, differing in their yellow vs black bills (3); bluish-grey vs plumbeous-grey plumage in male (1); larger size (effect size for bill height from published data (1) 2.49, score 2); distinct habitat (grasslands with greater shrub density on dry and steeply sloping terrain vs grasslands with scattered sub-shrubs associated with mesic environments near poorly drained and flatter soils (1); song like plumbea’s but with clear (whistled) introductory syllables and unique call notes (1) (at least 2). Monotypic.

Subspecies

Monotypic.

Distribution

Araucaria forests of S Brazil (Paraná S to Rio Grande do Sul); migrates N to cerrado savannas of C Brazil (E Goiás, W & C Minas Gerais, SW Bahia) (1).

Habitat

Breeds in grasslands with dense tall shrubs associated with Araucaria angustifolia forests, especially dry soils on steeply sloping terrain in valleys, between 650 and 950 m, with the most important grassland types used by S. beltoni locally known as “guamirinzal” and “vassoural”; in the former, Myrcia bombicina (Myrtaceae) or Escallonia megapotamica (Escalloniaceae) are the dominant shrubs, whereas in “vassoural” Baccharis dracunculifolia (Asteraceae) is dominant, with many species of Eupatorium and other Baccharis spp. mixed with the main shrubs, and short trees, e.g., Agarista eucalyptoides (Ericaceae), Quillaja brasiliensis (Quillajaceae) and Schinus spp. (Anacardiaceae) are scattered prominently across these shrub-grasslands, with tall and short grasses interspersed in a mosaic with patches of shrubs. In the zone of breeding contact with formerly conspecific S. plumbea, the present species prefers areas grasslands with greater shrub density on dry and steeply sloping terrain. During the austral winter, uses cerrado and other habitats with much tall grass.

Movement

Long-distance migrant. Arrives in breeding areas in mid Oct and departure can start as early in late Jan, disappearing completely in the first week of Mar, with movements of up to c. 1500 km from N Rio Grande do Sul to Minas Gerais and surrounding states; passage through intervening areas occurs Feb–Jul and Sept–Oct. During the austral autumn, observed in small flocks mixed with congeners including S. hypoxantha, S. melanogaster, S. pileata and S. caerulescens, and on the wintering grounds in S & SW Minas Gerais, they may join mixed flocks with S. plumbea, S. collaris, S. bouvreuil, S. palustris, S. cinnamomea and S. nigricollis.

Diet and Foraging

Apparently almost nothing published, but has been observed feeding on seeds of purple speargrass (Piptochaetium stipoides) while perched.

Sounds and Vocal Behavior

Calls generally seem to be stronger and more melancholic than those of S. plumbea; they have a single element and tend to be longer than equivalent notes of S. plumbea. Main call type initially drops in frequency, then rises again, whereas in S. plumbea it only drops in frequency and is shorter. Like other seedeaters that are song mimics, S. beltoni sings structurally elaborate songs, including a well-demarcated introduction with clear notes, sometimes followed by a more complex and faster portion, with no clear pattern but loaded with mimicry of syntopic birds. Songs show a distinction between the introduction and the rest of the song, with a predominance of clear and incisive notes (whistled notes) in the introductory portion. In S. plumbea, the separation between the introduction and the remainder is often difficult to perceive, but both species exhibit marked regional variation in voice, although songs of the present species possess unique syllables (in the introduction) between different localities.

Breeding

Season early Nov to early Mar, with most activity between the second week of Nov and late Dec; the first birds fledged in late Nov, with peak fledging in second half of Dec, and nests in Jan–Feb are commonly second or third attempts by pairs whose earlier nests failed. Nest, its materials and construction undescribed. Clutch usually two eggs (range from 1–3), with the largest clutches recorded only early in the breeding season, with single-egg clutches limited to second re-nesting attempts, thus, clutch size decreases as the season progresses, but egg size and colour apparently unreported in the literature; incubation by female alone and commences with the first or second egg, 11–13 days (usually 12); both sexes provision and care for nestlings, which fledge after 8–11 days when just 9 g. Mean time between first and second nesting attempts was c. 17 days (range 4–50) and between second and third attempts was c. 14 days (range 4–33). Some 60% of monitored females made a second confirmed nesting attempt, of which 25% made a third attempt in the same season; in 85% of cases, the second nesting attempt was preceded by a failure and 15% occurred after a successful attempt, but just one first and second successful nesting attempt was recorded, all five third nesting attempts were preceded by two failures and only one third nesting attempt was successful. Predation was cause of failure in 48% of nests that failed; twice, the incubating female was predated (probably at night) but not the eggs; desertion occurred exclusively during the construction and incubation stages, and was the second most important cause of nest failure, with cattle trampling causing 13% of failures and poorly constructed nests, human-promoted landscape burns and parasitism by the botfly Phylornis seguy being the other determined causes of nest loss. Better-concealed nests in vegetation tended to have a higher probability of success, similar to S. melanogaster nests in same region.

Conservation Status

Conservation status on Birdlife VU Vulnerable

VULNERABLE. Grassland habitat loss and intensive trapping for use as cagebirds are the primary concerns. Illegal trapping has already made the present species much rarer than other sympatric species of Sporophila, and means that it is especially coveted. Indiscriminate trapping of males probably threatens breeding success and juvenile recruitment, and experienced bird keepers have reported that trapping pressure has already caused local extinctions. Upland grasslands are being rapidly converted to agriculture, while commercial Pinus spp. plantations are a considerable threat as extensive monocultures of conifers are often planted in areas used by this species to breed, because they are often stony and have very shallow soils unfit for conventional farming. Habitat loss is of concern throughout the species’ range. Cerrado and associated grassland environments are being progressively eradicated and even inaccessible land inappropriate for agriculture has been lost due to the construction of hydroelectric dams. Some river valleys that feature remnants of specific grasslands crucial to S. beltoni and other threatened grassland birds are part of the Brazilian government’s dam-construction programmes, while no breeding population has been found within a protected area, meaning the species is dependent on management practices in private farms.

Distribution of the Tropeiro Seedeater - Range Map
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  • Year-round
  • Migration
  • Breeding
  • Non-Breeding
Distribution of the Tropeiro Seedeater

eBird and Macaulay Library

Recommended Citation

del Hoyo, J., N. Collar, and G. M. Kirwan (2020). Tropeiro Seedeater (Sporophila beltoni), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.trosee1.01
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