Effect of habitat heterogeneity on bird assemblages in a grassland-forest ecotone in Brazil

Abstract

The present study evaluates differences in alpha and beta diversity and guild structure of bird assemblages along the ecotone between grassland and Araucaria forest in Southern Brazil. Birds were sampled by point counts (radius of 25 m) disposed in the grassland, in the grasslandforest edge, and in the forest interior, grouped in three blocks. Grassland presented low bird richness and abundance, and the bird composition and guild structure in grasslands were different from the edge and the forest interior. Grassland showed more granivores, while forest interior presented more omnivores, insectivores and insectivores/ frugivores. Notwithstanding, there was an overlap on the occurrence of some forest bird species in the edge and grassland, evidencing that the grassland plant structure composed of small forest patches and shrubs could facilitate bird movements, which, in turn, could influence forest expansion dynamics over the grassland.