Vila Bela da Santíssima Trindade is situated in western Mato Grosso, and the globally threatened Black-and-tawny Seedeater Sporophila nigrorufa was initially discovered there in the 1820s. Together with Wim van der Schot and Guy Kirwan, I visited this area in early August 2007. We found large numbers of the seedeater in some of the savanna areas south of the town. Crossing to the west bank of the Rio Guapore we also found the localised and poorly known Fawn-breasted Wren Thryothorus guarayanus.

The text below is an adapted extract from a paper recently published in issue 4 of the Neotropical Bird Club's birding magazine, Neotropical Birding (www.neotropicalbirdclub.org/), in spring 2009. You can see sample articles from earlier issues of the magazine on the Club's home page. If you are interested in Neotropical birds then the Club is well worth joining, especially as your membership fee helps to support conservation projects throughout the Neotropics.


Black-and-tawny Seedeater Sporophila nigrorufa in the cerrados of western Mato Grosso, Brazil

Guy M. Kirwan and Juan Ignacio Areta


The extraordinary travels of the Austrian Johann Natterer in Brazil (during 1817 to 1835) yielded the discovery of such extraordinary and subsequently long-lost birds as Buff-cheeked Tody-Flycatcher Todirostrum (Poecilotriccus) senex, Pelzeln’s Tody-Tyrant Hemitriccus inornatus, White-tailed Tityra Tityra leucura, and Hooded Seedeater Sporophila melanops all belongs to Natterer. The first two of these went unseen again until the 1990s, whilst the spectacular, Phoenix-like, resurrection of the Tityra from the deepest depths of obscurity into which it had sunk was recently announced by Andrew Whittaker. The seedeater, first and last seen in October 1823, remains the challenge for both taxonomists and birdwatchers amongst ‘lost’ taxa in Brazil.

In late 1826 Natterer was at Vila Bela da Santíssima Trindade, where he discovered the bird we now know as Black-and-tawny Seedeater Sporophila nigrorufa. Just five years later the species was found in Bolivia, from which material the species was described. (Natterer’s innumerable finds were in fact only fully detailed by Pelzeln, more than 40 years after the event in many cases.) The species then effectively disappeared from the ornithological ‘radar’ until October 1979, when Bob Ridgely observed a male east of Corumbá, in Mato Grosso do Sul, Brazil. Ten years later it resurfaced in Bolivia.

BirdLife International (www.birdlife.org) currently categorises Black-and-tawny Seedeater as Vulnerable. It is still known from just eight sites in eastern Bolivia (in dpto. Santa Cruz) and three in adjacent Brazil (all in Mato Grosso and Mato Grosso do Sul), with potentially three additional sites in Mato Grosso probably only occupied during the austral winter. In Bolivia the major breeding area is Flor de Oro in Noel Kempff Mercado National Park. Its presence is to some extent seasonal there, with several hundred birds estimated in late May, slightly lower numbers during the breeding season in October to December, but very few apparently present in July–October. In 2005 Black-and-tawny Seedeater was observed in Otoquis National Park, on the border between Bolivia and Paraguay, but to date the species has not been found in the latter country. The species’ stronghold in Brazil remains the cerrados east and south of Vila Bela da Santíssima Trindade, Mato Grosso, where 55 were counted in January 1988, and at least 100 in July 1997, with other records in March. The southernmost record in Brazil pertains to an unspecified number of S. nigrorufa within a mixed-species flock of 100+ Sporophila of 11 species in a 500-ha remnant of campo sujo at Fazenda Rio Negro, Pantanal de Nhecolândia, Mato Grosso do Sul, in November 20053. Given that Tubelis & Tomas omitted S. nigrorufa from their checklist of the birds of the Pantanal wetland for lack of evidence, and that the Nhecolândia observations were made during the breeding season, further surveys of this area appear warranted.

During August 2007 and June 2008, we visited Vila Bela da Santíssima Trindade. During both visits, Black-and-tawny Seedeaters were found in large groups, consorting with other seedeaters, whereas later in the year when breeding they are found in pairs or much smaller feeding parties. In August, Kirwan found large flocks of S. nigrorufa (comprising 100–200 individuals) also including several Rusty-collared Seedeaters S. collaris, a handful of Dark-throated Seedeaters S. ruficollis and similarly small numbers of Tawny-bellied Seedeaters S. hypoxantha, Rufous-rumped Seedeaters S. hypochroma and White-bellied Seedeaters S. leucoptera bicolor. All of the males (Figs. 1–3) that were closely studied were in very fresh plumage, with pale tips and fringes to all of the wing-coverts, pale bases to the crown and mantle feathers, offering an overall greyer (less black) effect to these tracts, as well as very broad white fringes to the tertials and very neat pale tips to the rectrices, which were all very point-tipped. At this season (pre-breeding) many still had rather paler bills (not all black), although a few did have all-dark bills. Some presumed younger males were also observed closely; these were much paler chestnut below, with rather browner caps and much less obvious fringes to the wing feathers, but otherwise similar to adult males. To our knowledge, female Black-and-tawny Seedeater has never been well illustrated in the literature before. However, as earlier noted by Ridgely & Tudor, it seems doubtful whether females of this species could be reliably separated from those of other ‘rufous-plumaged’ Sporophila if observed alone or mixed with other species.

FURTHER READING
1. Bates, J. M., Parker, T. A., Capparella, A. P. & Davis, T. J. (1992) Observations on the campo, cerrado and forest avifaunas of eastern Dpto. Santa Cruz, Bolivia, including 21 species new to the country. Bull. Brit. Orn. Club 112: 86–98.
2. BirdLife International (2008) Species factsheet: Sporophila nigrorufa. www.birdlife.org (accessed 7 July 2008).
3. Cestari, C. (2006) Novos registros de aves do gênero Sporophila para o Pantanal. Atualidades Orn. 129: 7.
4. Collar, N. J., Gonzaga, L. P., Krabbe, N., Madroño Nieto, A., Naranjo, L. G., Parker, T. A. & Wege, D. C. (1992) Threatened birds of the Americas: the ICBP/IUCN Red Data book. Cambridge, UK: International Council for Bird Preservation.
5. Davis, S. E. (1993) Seasonal status, relative abundance, and behavior of the birds of Concepción, Departamento Santa Cruz, Bolivia. Fieldiana Zool. 71.
6. Güller, R. (2008) Sporophila nigrorufa (d´Orbigny y Lafresnaye, 1837), una nueva especie para la avifauna Argentina. Nótulas Faunísticas, Ser. 2, 20: 1–3.
7. Pelzeln, A. von (1868) Zur Ornithologie Brasiliens: Resultate von Johann Natterers Reisen in den Jahren 1817 bis 1835. A. Pichler’s Witwe & Sohn, Wien.
8. Ridgely, R. S. & Tudor, G. (1989) The birds of South America, 1. Oxford: Oxford University Press.
9. Silva, J. M. C. (1999) Seasonal movements and conservation of seedeaters of the genus Sporophila in South America. Stud. Avian Biol. 19: 272–280.
10. Silveira, L. F. & D’Horta, F. M. (2002) A avifauna da região de Vila Bela da Santíssima Trindade, Mato Grosso. Pap. Avuls. Zool., São Paulo 42: 265–286.
11. Stattersfield, A. J., Crosby, M. J., Long, A. J. & Wege, D. C. (1998) Endemic Bird Areas of the world: priorities for biodiversity conservation. Cambridge, UK: BirdLife International.
12. Tubelis, D. P. & Tomas, W. M. (2002) Bird species of the Pantanal wetland, Brazil. Ararajuba 11: 5–37.
13. Whittaker, A. (2008) Field evidence for the validity of White-tailed Tityra Tityra leucura Pelzeln, 1868. Bull. Brit. Orn. Club 128: 107–113.
14. Willis, E. O. & Oniki, Y. (1990) Levantamento preliminar das aves de inverno em dez áreas do sudoeste de Mato Grosso, Brasil. Ararajuba 1: 19–38.


GUY M. KIRWAN
74 Waddington Street, Norwich NR2 4JS, UK

JUAN IGNACIO ARETA
Grupo FALCO, Calle 117 Nro. 1725 e/67 y 68, Buenos Aires, La Plata, (1900), Argentina