Observational field studies provide insight on the multifunctional nature of birdsong. For example, if song production were limited to pre‐fertilization, then that would suggest a mate attraction function. If it were used throughout the breeding season and in response to intruding males, then that would suggest a territorial defence function. In the present study, we determined the daily and seasonal singing patterns of male ruby‐crowned kinglets Regulus calendula in Labrador, Canada, using microphone arrays in two breeding seasons. Using a playback experiment, we simulated a territorial intrusion to compare the structure of songs produced while defending a territory to the structure of songs produced during solo and contest singing. Singing peaked in the early part of the breeding season and then declined continuously for the remainder of the season, which suggests that the songs function in mate attraction. Singing peaked 2–3 h after dawn, and then declined steadily until it stopped at 10 pm. Some nocturnal singing was observed, but no dawn singing was observed. A high probability of signal overlap by heterospecific songs at dawn would hinder signal recognition and explain the observed delay in peak singing activity. Vocal responses to playback suggested a function in territory defence. However, there were no significant differences in the duty cycle, frequency modulation and bandwidth of songs in relation to the context of song production, though songs were shorter in the intrusion context than during solo singing. Overall, the study provides the first quantitative description of the effects of time of day, time of year and social context on singing behaviour in this understudied species.

中文翻译：

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红宝石王冠金盏花的歌唱行为与时间，年份和社会背景的关系

观察性野外研究提供了有关禽歌的多功能性的见解。例如，如果歌曲的制作仅限于预受精，那么这将暗示伴侣吸引功能。如果在整个繁殖季节使用它，并且是对入侵的雄性的反应，那么这将暗示其领土防御功能。在本研究中，我们确定了雄性红宝石加冕小金花金盏花的日常和季节性唱歌方式在加拿大拉布拉多的两个繁殖季节使用麦克风阵列。通过播放实验，我们模拟了一个领土入侵，以比较在捍卫领土时所产生的歌曲结构与独奏和比赛唱歌时所产生的歌曲结构。歌唱在繁殖季节的早期达到顶峰，然后在整个季节的剩余时间内不断下降，这表明歌曲在伴侣的吸引中起作用。歌声在黎明后的2-3小时达到峰值，然后稳定下降直到晚上10点停止。观察到一些夜间唱歌，但没有观察到黎明唱歌。异种歌曲在黎明时出现信号重叠的可能性很高，这会阻碍信号识别，并解释峰值演唱活动中观察到的延迟。对回放的人声反应建议在区域防御中发挥作用。然而，尽管在侵入环境中的歌曲比在独唱期间的歌曲短，但歌曲的占空比，频率调制和带宽与歌曲产生的环境没有显着差异。总的来说，这项研究首次定量描述了这一时期的物种中一天中的时间，一年中的时间和社会背景对唱歌行为的影响。