Avifauna associated to an urban extend of the Sorocaba river, Southeastern Brazil

Abstract

This study aimed to characterize the avifauna associated to the Sorocaba River, a typical urban river in Southeastern Brazil. It crosses the city having the same name, along which different human activities are carried out as recreation and fishing. There, several bird species might find sites for resting, feeding and nesting. We surveyed birds weekly, from September 2008 to September 2009, by 16 point counts (A1 to A16). The quantitative survey registered 65 species (32 Passeres and 33 non-Passeres), and the most well-represented family was Tyrannidae (n = 9). The most frequent species were Egretta thula, Amazonetta brasiliensis, Vanellus chilensis, Pitangus sulphuratus, Ardea alba and Pygochelidon cyanoleuca (FO = 100%). The higher abundance index values were 46.5 (1626 contacts) for Pygochelidon cyanoleuca, 14.4 (500 contacts) for Phalacrocorax brasilianus and 12.9 (452 contacts) for Amazonetta brasiliensis. The most representative trophic categories were insectivores (n = 26), piscivores (n = 11) and omnivores (n = 10). The cluster analysis revealed the existence of three very similar pairs of points (100 and 95% of information remaining). Conspicuous differences in the composition of bird fauna along the studied area were detected, probably due to its environmental characteristics and the degree of human disturbance. Moreover, significant differences were observed between the sightings of dry and wet seasons, probably due to the reproductive and migratory activities and an increased availability of food resources that is supposed to happen in the wet season. In this sense, conservation practices should provide the maintenance of habitat heterogeneity, recovering the riparian forests, beaches and marshes, and an effective planning of human activities in their surroundings as well.