Bird community composition in an urban area in southern Brazil

Abstract

Urbanization is a major cause of richness decrease of birds by modification of their natural habitat, leading to scarcity of resources to most species. Therefore, demanding species could become locally scarce or extinct, while others find food and reproduction resources increasing its abundance. Parks in urban matrices may include fragments of natural vegetation that, in adequate size and integrity, can maintain the regional biodiversity. This study analyses the bird community composition of Souza Cruz Environmental Park (Parque Ambiental Souza Cruz) in Cachoeirinha City, Rio Grande do Sul, Brazil, through a period of three years. A field survey was conducted to evaluate abundance, richness and other relevant ecological aspects of bird species. Birds were grouped by trophic guild and habitat change sensitivity. We use point counts method from 2009 to 2012, totalizing 120 hour of listening. We registered 149 bird species in 44 families, with Tyrannidae (17 species) as the most representative. Estimated richness was 166.5 ± 4.73 species. From all, 12 species are endemic to the Atlantic Rainforest. There was a predominance of insectivores, omnivores and species showing low sensibility to habitat changes. Bird diversity in the third year was lower than in the first and second sampling years. Richness was similar between the first and second sampling years. This bird community represents a significant portion (66%) of avifauna registered in the Porto Alegre metropolitan green areas. This is an important result, once the surroundings of the study area have been converted to an urban area.

Keywords: fragmented areas, urbanization, avifauna, ecological succession.