Temporal variation in the abundance of waterbird species in a coastal lagoon in the northern Rio de Janeiro, southeastern Brazil

This study evaluated the influence of different rainfall regimes on numerical fluctuations of waterbird species in Ribeira Lagoon, Quissamã, northern Rio de Janeiro state, Brazil. Bird counts were conducted on a monthly basis between August 2008 and July 2009, totaling 12 visits. Rainfall data were obtained at the nearest meteorological automatic station. A total of 50 species were classified into 6 functional groups. Bird richness and abundance were greater during the dry season (May/August). Spearman’s coefficient between bird abundance and monthly rainfall was -0.77 (P = 0.003). Similarly, there was a significant negative correlation between rainfall values and the abundance of dabbling, diving, and gleaning bird groups. The exponential prediction model was the most appropriate to the dataset (R² = 0.53), with a correlation coefficient between predicted and observed abundance values of 0.76 (P = 0.006). The model obtained predicts a significant decline in the total number of birds in months with rainfall over 100 mm in Ribeira Lagoon.