Environmental factors affecting understory bird abundance and richness in Reserva Ducke, Brazil.

Forest structure components and habitat complexity has been increasingly understood to explain patterns of avian species diversity in untouched, primary, tropical forests. Three possible environmental and topographic variable predictors were studied in Reserva Florestal Adolpho Ducke (RFAD) to test whether they had any influence over understory bird species richness and abundance. Avifauna was surveyed over a period of four days which was then pooled together with available bird data which had previously been collected at the reserve between the years 2012-2014. All avifauna in this study was sampled using thirteen 10m mist nets on the 250m trails in the RAPELD grid. Mean canopy cover was taken from ten of the plots in the RAPELD grid, elevation from all 72 plots and previously available herb data from 59 plots. No significant relationships were found between the landscape and forest components and bird species and individuals. The results of the Principal Components Analysis, however, showed that herb abundance is the most important variable to determine the differences between plots in the reserve. The study indicates that the topic needs to be thoroughly investigated in order to determine how different forest features and environmental factors can act together simultaneously to instigate changes in avian communities at local scales.