Bird species distribution in a complex Amazonian landscape: species diversity, compositional variability and biotic-environmental relationships

The purpose of this study is to analyze the avifauna of a complex Amazonian landscape to understand the contribution of habitat heterogeneity to the regional bird diversity. Birds were sampled with mist nets and point counts in six vegetation types in the Jau National Park, Brazilian Amazon. White sand campinas and white sand forests were less diverse than other vegetation types. Despite their lower diversity, the bird faunas of white sand campinas and open canopy flooded forests were very distinct at the landscape scale. Dominance of individuals in white sand campinas, open canopy flooded forests and a white sand forest was higher than in other vegetation types. Number of species was correlated with area and structural complexity of the vegetation. Species composition was distinct between vegetation types and ordinations of sites revealed ecological gradients related to the soil variability and flooding regimes. Habitat heterogeneity provided by the river's seasonal flooding and the distribution of soil types is important for structuring bird communities in the study region. Additionally, allopatric speciation and dispersal events play important roles in the diversification of bird communities in the Jau National Park.A proposta deste estudo e analisar a avifauna de uma complexa paisagem amazonica para entender a contribuicAo da heterogeneidade de habitat para a diversidade de aves. As aves foram amostradas com redes de captura e contagens por pontos em seis tipos de vegetacAo no Parque Nacional do Jau, Amazonia brasileira. Campinas e campinaranas apresentaram menor diversidade de aves. Apesar da baixa diversidade, as avifaunas das campinas e matas alagaveis de copa aberta foram muito distintas na escala da paisagem. A dominancia de individuos nas campinas, matas alagaveis de copa aberta e campinaranas foi superior comparada aos outros tipos de vegetacAo. Numero de especies de aves foi correlacionado com area e complexidade estrutural da vegetacAo. A composicAo de especies foi distinta entre os tipos de vegetacAo e ordenacoes dos sitios revelaram gradientes ecologicos relacionados a variabilidade de solos e regime de alagamento dos rios. Heterogeneidade de habitats providenciada pelo alagamento sazonal dos rios e variabilidade de solos e importante na estruturacAo das comunidades de aves na regiAo de estudo. EspeciacAo alopatrica e eventos de dispersAo tambem desempenham importante papel na diversificacAo da avifauna do Parque Nacional do Jau.