The effects of long‐distance migration on the evolution of moult strategies in Western‐Palearctic passerines

• Published in: Biological Reviews
• Main Authors: Kiat, Yosef, Izhaki, Ido, Sapir, Nir
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2018
• Subjects: Arctic
• Online Access: http://dx.doi.org/10.1111/brv.12474; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbrv.12474; https://onlinelibrary.wiley.com/doi/pdf/10.1111/brv.12474

ABSTRACT Although feathers are the unifying characteristic of all birds, our understanding of the causes, mechanisms, patterns and consequences of the feather moult process lags behind that of other major avian life‐history phenomena such as reproduction and long‐distance migration. Migration, which evolved in many species of the temperate and arctic zones, requires high energy expenditure to endure long‐distance journeys. About a third of Western‐Palearctic passerines perform long‐distance migrations of thousands of kilometres each year using various morphological, physiological, biomechanical, behavioural and life‐history adaptations. The need to include the largely non‐overlapping breeding, long‐distance migration and feather moult processes within the annual cycle imposes a substantial constraint on the time over which the moult process can take place. Here, we review four feather‐moult‐related adaptations which, likely due to time constraints, evolved among long‐distance Western‐Palearctic migrants: ( i ) increased moult speed; ( ii ) increased overlap between moult and breeding or migration; ( iii ) decreased extent of plumage moult; and ( iv ) moult of part or all of the plumage during the over‐wintering period in the tropics rather than in the breeding areas. We suggest that long‐distance migration shaped the evolution of moult strategies and increased the diversity of these strategies among migratory passerines. In contrast to this variation, all resident passerines in the Western Palearctic moult immediately after breeding by renewing the entire plumage of adults and in some species also juveniles, while in other species juvenile moult is partial. We identify important gaps in our current understanding of the moult process that should be addressed in the future. Notably, previous studies suggested that the ancestral moult strategy is a post‐breeding summer moult in the Western Palearctic breeding areas and that moult during the winter evolved due to the scheduling of long‐distance migration immediately ...