Heat dissipation capacity influences reproductive performance in an aerial insectivore

Climatic warming is predicted to increase the frequency of extreme weather events, which may reduce an individual's capacity for sustained activity due to thermal limits. We tested whether the risk of overheating may limit parental provisioning of an aerial insectivorous bird in population decline. For many seasonally breeding birds, parents are thought to operate close to an energetic ceiling during the 2-3 week chick-rearing period. The factors determining the ceiling remain unknown, although it may be set by an individual 's capacity to dissipate body heat (the heat dissipation limitation hypothesis). Over two breeding seasons we experimentally trimmed the ventral feathers of female tree swallows (Tachycineta bicolor, Vieillot, 1808) to provide a thermal window. We then monitored maternal and paternal provisioning rates, nestling growth rates, and fledging success. We found the effect of our experimental treatment was context-dependent. Females with an enhanced capacity to dissipate...

据预测，气候变暖将增加极端天气事件的发生频率，此类事件可通过热极限约束降低个体的持续活动能力。本研究旨在验证过热风险是否会限制种群衰退中的食虫飞禽的双亲育雏投喂行为。对于多数季节性繁殖鸟类而言，双亲在2至3周的育雏阶段通常处于能量上限附近运作。目前决定该能量上限的具体因素仍未明确，但有假说认为其由个体的体热散失能力决定（热散限制假说，heat dissipation limitation hypothesis）。在两个繁殖季中，我们通过实验修剪雌性树燕（Tachycineta bicolor, Vieillot, 1808）的腹羽，为其营造散热窗口。随后我们监测了双亲的投喂频次、雏鸟生长速率以及离巢成功率。我们发现，实验处理的效应具有情境依赖性：腹羽修剪后体热散失能力得到增强的雌性个体……