A New Look at the "Species-Poor" Central Amazon: The Avifauna North of Manaus, Brazil

Abstract

The birds of the Fazendas Dimona, Porto Alegre, and Esteio, and adjacent areas, ca. 80 km north of Manaus, Amazonas, Brazil, have been intensively studied since 1979. Stotz and Bierregaard (1989) published a list of 352 species, based on seven years of study. Here we modify that list based on an additional eight years of work at the same sites. We add 49 species, revise the identification of four species, and remove seven species, for a total of 394 species. We also list 12 additional species as "hypothetical," requiring further substantiation, and revise the status of numerous species. Additions include 22 species believed to have been overlooked previously, 15 species believed to have colonized the area recently in response to anthropogenic hange, and 12 species that are probably vagrants from habitats not well represented in the study area. Status revisions reflect an increase in availability and diversity of secondary habitats or better knowledge of vocalizations of birds that are much more commonly heard than seen. Specimens indicate that Campylorhamphus procurvoides and Hemitriccus zosterops, not C. trochilirostris and H. minor, are present at the site. We also present evidence that Hemitriccus z. zosterops and H. z. griseipectus are distinct species, and we report the first Brazilian records (including specimens) of Phylloscartes virescens. Comparison with the avifauna of two well-studied sites in Amazonian Peru, Manu National Park and Tambopata Reserve, reveals similar species richness in the terra firme forest component of all three sites. The difference in richness between the sites is because of the variety of habitat types present at each. We suggest that habitat heterogeneity, not primary productivity or rainfall as have been proposed elsewhere, is the major determinant of patterns in bird species richness within Amazonia. Resumo. As aves das fazendas Dimona, Porto Alegre, e Esteio, e das areas adjacentes, a cerca de 80 km ao norte de Manaus, Amazonas, Brasil, foram estudadas intensivamente desde 1979. Stotz e Bierregaard (1989) publicaram uma lista com 352 especies, baseada em sete anos de estudo. Modificamos essa lista a partir de mais oito anos trabalhando nas mesmas areas. Acrescentamos 49 especies, corrigimos a identificacao de quatro, e removemos sete, resultando num total de 394 especies. Tambem listamos doze especies adicionais como "hipoteticas," que necessitam maiores evidencias de sua ocorrencia, e revisamos o status de varias especies. Adicoes incluem 22 especies provavelmente negligenciadas anteriormente, 15 especies que acreditamos terem colonizado a area recentemente m resposta a mudancas antropogenicas, e 12 especies que provavelmente sao visitantes irregulares de ambientes pouco representados na area de estudo. As revisoes de status refletem urn aumento na disponibilidade e diversidade de vegetasao secundaria e um maior conhecimento das vocalizacoes de aves que sao muito mais comumente ouvidas do que vistas. Especimes indicam a presenca na area de estudo de Campylorhamphus procurvoides e Hemitriccus zosterops, em vez de C. trochilirostris e H. minor. Tambem apresentamos evidencia de que Hemitriccus z. zosterops e H. z. griseipectus sao especies distintas, e confirmamos com exemplares o primeiro registro de Phylloscartes virescens para o Brasil. A comparacao desta avifauna com a de duas areas igualmente bem conhecidas na Amazonia peruana, o Parque Nacional de Manu e a Reserva Tambopata, revela uma riqueza de especies semelhante nas areas de floresta de terra firme dos tres locais. A