Insights into the phenology of migration and survival of a long migrant land bird
Lay summaryFor polygamous long-migrant birds, the choice of migration strategy depends on social pressure and experience and influences the chance of survival. If you are a male, youd better leave early in the spring to secure the best site to show off. In fall, juveniles have a hard time surviving to migration as they leave before the adults and lack experience on where to go and where to stop to rest.\n\nAbstractThe process of migration stems from an adaptation of climatic seasonality and animals have developed various strategies to complete the journey between a wintering and breeding ground. Understanding the migratory behavior and determining when and where mortality occurs during the annual cycle is fundamental to understand population dynamics and implement appropriate conservation measures. Based on a big data set and advanced statistical methods, we inspected the phenology of migration of a polygynous land bird, the Macqueens bustard, Chlamydotis macqueenii. We explored its migration strategies between sex, age, season and geographical origin. We show that departure for migration depended on age in the fall with juveniles being the first to leave and on age and sex in the spring with juveniles departing later and males induced to arrive early in spring to secure high-quality territories. Birds breeding at higher latitudes were the first to leave in the fall and more likely to perform longer stopovers. Bustards exhibited different strategies for spring and fall migrations: spring migration was significantly longer than fall migration with more but shorter stopovers. Survival was lower for juveniles experiencing their first migration and for all birds during fall migration and on their wintering ground. Experience linked to social hierarchical pressures and environmental conditions might be the key drivers of migration strategies and survival in long-distance polygynous migrants.