Wading bird functional diversity in a floodplain: Influence of habitat type and hydrological cycle

Abstract

AbstractWaterbirds play important roles in maintaining ecosystem functioning in wetlands. However, the lack of essential information about the levels of interaction between waterbirds and wetland characteristics is a major impediment for service valuation. In this study, we examined the influence of the flood pulse across different freshwater habitats on the functional diversity and possible assembly structuring mechanisms of herons and storks in a neotropical floodplain. We investigated functional richness, evenness and divergence as descriptors of the functional diversity in rivers, channels and both connected and isolated lagoons across different phases of the hydrological cycle. We also compared observed values of functional diversity with expected null models to untangle the main mechanisms driving assemblages. We found spatiotemporal variation in functional diversity in wader assemblages of the high Paraná River floodplain. The functional diversity of Pelecaniformes and Ciconiiformes varied mainly in rivers, channels and connected lagoons opposed to isolated lagoons in a floodplain, and mostly during flood events, right after floods or after a long period of drought. This suggests that the variation in the water level plays different roles in maintaining wading birds' functional diversity in connected and isolated habitats. Also, wading bird assemblages in this floodplain may be structured by neutral mechanisms, independent of habitat type or hydrological period, which may support the idea that species traits are not important in explaining their coexistence patterns. Our study contributes to the understanding of how environmental variations may affect functional diversity, a first step towards understanding how changes in waterbird communities affect the magnitude and stability of services provided by them.