Vocal performance increases rapidly during the dawn chorus in Adelaide’s warbler

Many songbirds sing intensely during the early morning, resulting in a phenomenon known as the dawn chorus. We tested the hypothesis that male Adelaide’s warblers (Setophaga adelaidae) warm up their voices during the dawn chorus. If warming up the voice is one of the functions of the dawn chorus, we predicted that vocal performance would increase more rapidly during the dawn chorus compared to the rest of the morning and that high song rates during the dawn chorus period contribute to the increase in vocal performance. The performance metrics recovery time, voiced frequency modulation, and unvoiced frequency modulation were low when birds first began singing, increased rapidly during the dawn chorus, and then leveled off or gradually diminished after dawn. These changes are attributable to increasing performance within song types. Reduction in the duration of the silent gap between notes is the primary driver of improved performance during the dawn chorus. Simulations indicated that sin..., ,

多数鸣禽会于清晨开展高强度鸣唱，由此形成了被称为黎明合唱（dawn chorus）的典型现象。我们针对雄性阿德莱德林莺（Setophaga adelaidae）在黎明合唱期进行鸣唱热身这一假说展开了实证检验。若鸣唱热身确为黎明合唱的功能之一，我们预测：相较于晨间其余时段，鸣唱表现（vocal performance）会在黎明合唱期提升得更为迅速；且黎明合唱期的高鸣唱频次，会推动鸣唱表现的整体提升。当鸣禽首次开始鸣唱时，鸣唱表现指标（performance metrics）中的恢复时长、有声频率调制与无声频率调制均处于较低水平；在黎明合唱期，这些指标会快速升高，随后在日出后趋于平稳或逐渐回落。上述变化可归因于同一鸣唱类型内鸣唱表现的逐步提升。鸣唱音符间静默间隙的时长缩短，是黎明合唱期鸣唱表现提升的核心驱动因素。模拟实验结果表明，正弦……