The annual cycle activities of birds from Serra da Mantiqueira, Brazil

Abstract The timing of feather molting and breeding, two key activities in the avian life cycle, varies widely among species. These variations are shaped by each species’ unique ecological traits and their interactions with dissimilar environmental factors, such as seasonal changes in weather and food availability. Understanding these seasonal patterns of molt and breeding represents an important step toward advancing our knowledge of avian ecology. In this study, we analyzed bird banding data collected from July 2019 to May 2025 through the long-term monitoring program at the Mantiqueira Bird Observatory (OAMa). With circular statistics, we tested the seasonality of breeding, feather molt, and fat accumulation across a bird community in Brazil’s Atlantic Forest. Molting, breeding, and fat accumulation followed well-defined seasonal patterns: peak breeding occurs in the early wet season (October to December), molt peaks at the end of the wet season (January to March), and fat accumulation peaks in the dry season (around July). These are fundamental aspects about species ecology and life history, and this study contributes to our understanding of the full annual cycle of tropical avifauna.