Seasonal niche tracking of climate emerges at the population level in a migratory bird

Abstract

Seasonal animal migration is a widespread phenomenon. At the specieslevel, it has been shown that many migratory animal species track similar cli-matic conditions throughout the year. However, it remains unclear whethersuch a niche tracking pattern is a direct consequence of individual behaviouror emerges at the population or species level through behavioural variabil-ity. Here, we estimated seasonal niche overlap and seasonal niche trackingat the individual and population level of central European white storks(Ciconia ciconia). We quantified niche tracking for both weather and climateconditions to control for the different spatio-temporal scales over which eco-logical processes may operate. Our results indicate that niche tracking is abottom-up process. Individuals mainly track weather conditions while cli-matic niche tracking mainly emerges at the population level. This resultmay be partially explained by a high degree of intra- and inter-individualvariation in niche overlap between seasons. Understanding how migratoryindividuals, populations and species respond to seasonal environments iskey for anticipating the impacts of global environmental changes