SEASONAL FLUCTUATIONS OF BIRDS, FRUITS, AND FLOWERS IN A SUBTROPICAL FOREST OF ARGENTINA1

Abstract

Abstract I quantified monthly variation in species composition and captures of birds in a premontane forest of northwestern Argentina. Seasonal patterns of frugivore-insectivores and nectarivores were compared with fruit and flower abundances, respectively. The composition of the entire bird community fluctuated seasonally; frugivore-insectivores showed a peak in captures during the wet season, insectivores peaked at the end of the dry season, and nectarivores peaked during the dry season. At a local scale (∼50 ha), captures of frugivore-insectivores were not correlated with number of plant species with ripe fruits for any vegetation stratum considered, but were correlated with a fruit phenology index that considers crop size. At a plot scale (∼7.5 ha), only understory flower abundance and captures of nectarivores were correlated, but only in the plot where both were more abundant. At a net-site scale (50 m2), captures of the Rufous-bellied Thrush (Turdus rufiventris) were correlated with understory fruit...