The influence of riparian forest fragmentation on birds in the River Hydrographic Basin, Rio Grande do Sul State

Abstract

Riparian zones of watercourses contribute to the conservation of birds, since they are used as ecological corridors for moving between forests by many species. The disturbance of these areas impacts negatively the species diversity of the regions. This study reports on the richness, abundance and feeding guilds of birds in different widths of riparian forest along watercourses, in Caí River Hydrographic Basin, Rio Grande do Sul. Eighteen fixed points of observation were randomized, at least 200 meters apart from each other, classified into three treatments of riparian forest width. Four observations were conducted at each point between January and May in 2009. The richness of bird species did not vary significantly between treatments, but we noticed that the composition varied according to the characteristics of each area, and a total of 97 species were identified. We recorded the presence of Limnoctites rectirostris, which is listed as an endangered species. Abundance, with 785 individuals, varied between treatments, with greater abundance of generalist species, which easily find resources in most environments, such as insectivorous birds, in areas with smaller riparian forest. We note that the fragmentation of riparian forest affects the ability to suit the needs of bioindicator birds because they use these environments for feeding, breeding and resting, and as ecological corridors. Thus, the restoration and preservation of riparian forests with a minimum coverage of 30 meters of the original vegetation are essential for bird species that indicate good environmental quality.

Key words: birds richness and abundance, feeding gilds, endangered species, riparian zones.