Density of invasive exotic palms affecting the understory avifauna in the Atlantic forest, Southeastern Brazil

Abstract

Biological invasion is a common process in natural environments around the world. In an invaded habitat, the interference of the invasive species in the ecosystem must be evaluated. The Alberto Löfgren State Park (PEAL) in São Paulo, southeastern Brazil, is suffering colonization from three species of invasive exotic palms (IEPs). The present study intended to verify how IEP density influences understory bird assemblages in this park. We have established two sampling areas with different palm density. Both line transects and mist nets were jointly used to survey the avifauna. Point-centered quarter sampling, allied with the counting of individual IEP, characterized the vegetation structure. IEP density differed significantly among sampling areas. We encountered a negative relation between IEP density and bird contacts. The results suggest that the increase in IEPs density interfere with the habitat use by birds. The control of palm populations is required, in order to avoid losses of birds in the future.