Composition and structure of the lacustrine bird communities of seasonally flooded wetlands of Western Brazilian Amazonia at high water

Abstract

We describe and analyze the bird community composition of the lacustrine water bodies of the seasonally flooded wetlands of the Mamirauá and Amaná Reserves, Amazonas, Brazil. Bird surveys were conducted in 54 water bodies within four water body systems aboard a speedboat, in July 2003, at the peak of the high water season. We recorded 2,823 individuals representing 79 bird species associated with aquatic environments, mostly resident; of these, 34 were aquatic (exclusively associated with aquatic environments), and 19 were primarily piscivorous. The aquatic bird communities of Mamirauá and Amanā comprise a few abundant species and a higher number of rare species. Seven species accounted for 71.7% of all 34 aquatic birds recorded. In general, the more elongated the water bodies, the lower the aquatic and piscivorous bird species richness, and the lower the bird abundance. Piscivorous bird abundance was not significantly related to water body shape. Matrices of bird species by water body were subjected to multivariate analysis using Principal Co-ordinate Analysis (PCoA). For the quantitative data (species abundance) and qualitative data (species presence/absence), the composition of the community of aquatic birds changed significantly among lacustrine water body systems, and was significantly affected by water body shape. The quantitative and qualitative composition of the piscivorous bird community did not change significantly among water body systems, and were not affected by water body shape. The numerical analyses revealed a remarkably different behavior of the communities of aquatic birds and piscivorous birds, the former changing significantly with lacustrine water body morphology and local geography (water body system), and the latter being relatively insensitive to variation in these parameters. Water body shape is one of the determinants of aquatic bird community composition in the seasonally flooded wetlands of this part of Amazonia.