Data from: Urban living alters moult dynamics in a passerine

Urbanization and habitat fragmentation can alter the timing of life history events, potentially leading to phenological mismatches, carryover effects, and fitness costs. Whereas urbanization and fragmentation are known to alter important aspects of breeding in many bird species, little is known about the effects of urbanization and habitat fragmentation on moult. To investigate the effects of urbanization and fragmentation on the annual moult, we compared the moult dynamics (onset, duration, and intensity) of urban, fragmented forest, and contiguous forest populations of the Carolina chickadee, a North American resident passerine that moults once per year immediately following the breeding season. Over three years, moult dynamics were similar in contiguous and fragmented forest populations, but wing moult started significantly earlier, and onset of moult varied less among years, in urban chickadees than in forest chickadees (fragmented and contiguous habitats pooled). Duration of wing moult did not differ between urban and forest populations, but urban birds moulted significantly fewer feathers simultaneously during peak moult, suggesting that individual feathers grew more rapidly. Our results show that urban living alters critical aspects of moult dynamics in a widespread songbird. Given the importance of moult dynamics for fitness during subsequent life history stages, and the large number of songbird species inhabiting urban areas, these results reveal previously unrecognized and potentially costly carryover effects of urban living on songbirds.城市化与栖息地破碎化会改变生物生活史事件的发生时序，进而可能引发物候错配、携带效应（carryover effects）以及适合度代价。尽管已有研究证实，城市化与栖息地破碎化会改变诸多鸟类物种繁殖行为的关键特征，但目前学界对二者对换羽（moult）的影响仍知之甚少。为探究城市化与栖息地破碎化对年度换羽的影响，本研究对比了城市化种群、破碎化林种群以及连续林种群的卡罗来纳山雀（Carolina chickadee）——一种每年仅在繁殖季后即刻完成一次换羽的北美留居雀形目鸟类——的换羽动态（起始时间、持续时长与换羽强度）。三年的观测结果显示，连续林与破碎化林种群的换羽动态并无显著差异；但相较于森林种群（破碎化林与连续林种群合并统计），城市化种群的翅羽换羽起始时间显著更早，且换羽起始时间在不同年份间的波动幅度更小。城市化种群与森林种群的翅羽换羽持续时长并无差异，但城市化个体在换羽高峰期同时更换的羽毛数量显著更少，这暗示单根羽毛的生长速度更快。本研究结果表明，城市生活环境会改变广布鸣禽换羽动态的关键特征。鉴于换羽动态对后续生活史阶段的适合度至关重要，且全球范围内有大量鸣禽栖息于城市环境中，本研究结果揭示了此前未被关注的、城市生活对鸣禽产生的潜在高代价携带效应。