Early singers attend to conspecific but not heterospecific behavioural cues at dawn

During the dawn chorus songbirds initiate singing activities just prior to sunrise. Environmental factors affect the timing of the dawn chorus, but relatively little is known about how behavioural cues influence chorus timing. We assessed whether early playback of conspecific and heterospecific song influenced chorus start times in two early-singing temperate species, hermit thrush (Catharus guttatus) and veery (C. fuscescens). We used arrays of GPS time-synchronized recorders to record the dawn chorus at 30 locations. In each location, thirty minutes prior to natural chorus initiation, we broadcast: (1) an early singing species (hermit thrush or veery), (2) a late singing species (black-throated green warbler or Nashville warbler), (3) a noise control, and (4) also recorded without playback (silent control). Playback treatments were separated by two-three days at each location. Both hermit thrush and veery sang significantly earlier in response to conspecific playback compared to noise...

在黎明鸣唱（dawn chorus）时段，鸣禽会于日出前启动鸣唱活动。环境因子会影响黎明鸣唱的时间节律，但学界对行为线索如何调控黎明鸣唱的启动时机，相关研究仍较为匮乏。本研究针对两种温带早鸣鸣禽物种——隐夜鸫（Catharus guttatus）与棕夜鸫（C. fuscescens），探究提前播放同种与异种鸣声是否会影响其黎明鸣唱的启动时间。我们采用GPS时间同步的录音设备阵列，在30个采样点位开展黎明鸣唱录音工作。在每个点位，我们会在自然黎明鸣唱启动前30分钟进行以下四种处理：（1）播放早鸣物种（隐夜鸫或棕夜鸫）的鸣声；（2）播放晚鸣物种（黑喉绿林莺或纳什维尔林莺）的鸣声；（3）噪音对照组（播放背景噪音）；（4）静默对照组（无回放，仅进行录音）。各点位的不同回放处理之间间隔2至3天。相较于噪音对照组，隐夜鸫与棕夜鸫在接收同种鸣声回放后，均显著提前启动鸣唱……