Data from: Age-dependent modulation of songbird summer feather moult by temporal and functional constraints

Time constraints influence various ecological, life-history and demographic properties of individuals and populations of many species throughout the annual cycle. Feather moult is a timely undertaking that is considered among the three most energy-demanding processes in the life cycle of birds. To deal with time pressure, passerines may shorten their moult duration using three non-mutually exclusive mechanisms: (1) only replacing part of the plumage, (2) increasing the speed of moult, and (3) postponing the renewal of some or all the plumage to a later season (i.e., from the summer to the over-wintering period). We used a comparative approach by measuring 12,349 individuals from 134 passerine species to explore how feather moult of juvenile and adult passerines is evolutionarily modulated under time constraints. The results indicate that breeding at northern latitudes and long-distance migration limit the time available for moult and that the consequences of time constraints were age-dependent. While the duration of adult summer moult decreased, the extent, rather than the duration, of juvenile moult declined under time constraints. This study highlights the importance of considering time constraints in order to enhance the understanding of selective forces that shape life history processes and their consequences throughout the annual routine.