Efeitos das características de lagos de água preta sobre a ocorrência e a abundância de aves piscívoras no arquipélago de Anavilhanas, rio Negro, Amazônia central, Brasil

Abstract

The influence of blackwater lakes characteristics on the occurrence and abundance of 12 fish-eating birds species in the Brazilian Amazon at the population level was evaluated. The central hypothesis was that local variations in lake characteristics should influence the occurrence and abundance of aquatic bird population in a tropical blackwater flooded forest system. An additional hypothesis was tested, the variation in the degree of isolation of the lakes, influence the occurrence and abundance of lake-living waterbirds. Bird surveys were conducted from November to December 2007 in 45 lakes within islands along 100 km of the Anavilhanas Archipelago, Rio Negro, Central Brazilian Amazonia. Multiple linear and multiple logistic statistical models were used to test the effects of nine variables, four physical, two chemical, two geographical, and one biotic, on the occurrence and abundance of 12 species of fish-eating birds. It was found that lake depth and water transparency influenced the occurrance and abundance of Ringed-Kingfisher (Megaceryle torquata) and abundance of Osprey (Pandion haliaetus), Cocoi Heron (Ardea cocoi) and Snowy Egret (Egretta thula). Lake isolation influenced the occurrence of Yellow-billed Tern (Sternula superciliaris) and Striated Heron (Butorides striata), and habitat richness has affected most of the fish-eating birds species. The results indicate that lake limnological and physical attributes are determinants of spatial variation in abundance and occurrence of fish-eating birds in the blackwater lake systems in central Brazilian Amazon.