Differences of birds communities of levee forests in wetlands

Abstract

Context. The fluvial forests on the islands, called levee forests, have vertical vegetation stratification. This contributes to the structural complexity that allows the presence of a great bird diversity on island and among fluvial corridors. Objectives. The aim was to evaluate differences in the avifauna of levee forest. We hypothesized that birds make a differential use of the different types of levee forests, which is reflected in the bird assemblage structure of each forest type. Methods. The “Delta del Paraná” Ramsar site is a wetland of international importance. A comparative analysis of richness, abundance and diversity was conducted in the different levee forests using the point count method. Results. Three types of levee forest were obtained: open, intermediate and closed forests, according to the floristic composition, tree cover, and height of the herb stratum. A total of 85 bird species were recorded. The differences in birds communities structure were found among seasons, between sites and among forest types. We found the highest richness, abundance, and diversity values in open forests. These reveals the structural variation in the levee forests offer in their interior and show the microscale variation in forest wetlands, which have been considered a single homogeneous environmental unit in floodplains. Conclusions. The finding that open forests harbor the most heterogeneous environment in levee environments reflects the importance of microspatial-scale heterogeneity in landscape configuration and how this variation contributes to maintaining high biodiversity in fluvial wetlands for both avifauna as for the biota in general.