Data from: Age-dependent modulation of songbird summer feather molt 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 molt 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 molt duration, using three non–mutually exclusive mechanisms: (1) replacing only part of the plumage, (2) increasing the speed of molt, and (3) postponing the renewal of some or all the plumage to a later season (i.e., from the summer to the overwintering period). We used a comparative approach by measuring 12,349 individuals from 134 passerine species to explore how feather molt 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 molt and that the consequences of time constraints were age dependent. While the duration of adult summer molt decreased, the extent, rather than the duration, of juvenile molt 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.

时间约束会在全年周期内，影响诸多物种种群及其个体的多项生态、生活史（life-history）及种群统计特征。换羽（feather molt）是一项受时间调控的生理活动，被认为是鸟类生活史中三大高能耗过程之一。为应对时间压力，雀形目鸟类（passerines）可通过三种非互斥的策略缩短换羽时长：（1）仅替换部分羽衣；（2）提升换羽速率；（3）将部分或全部羽衣的更新推迟至更晚的季节（即从夏季延后至越冬期）。本研究采用比较研究方法，对134种雀形目鸟类的12349个个体进行采样测量，以探究时间约束下幼鸟与成鸟换羽行为的进化调控机制。研究结果显示，在高纬度北部地区繁殖以及长途迁徙行为，会压缩换羽可用时长；且时间约束的影响存在年龄依赖性。在时间约束下，成鸟夏季换羽的时长有所缩短，而幼鸟换羽的特征变化则体现在换羽范围而非换羽时长上。本研究强调了考量时间约束的重要性，这有助于深化对塑造生活史过程及其全年生活周期后果的选择压力（selective forces）的理解。