Social environments can shape animal communication. Although mutual courtship displays are generally thought to function in private communication between a male and a female, we provide experimental evidence that they work in a broader social context than previously thought. We examined the audience effect on mutual courtship in blue-capped cordon-bleus, a socially monogamous songbird. This species is characterized by conspicuous courtship shared between sexes: Both sexes sing songs and sometimes add a unique dance display that looks like human tap dancing. We found that in both sexes, multimodal courtship displays (song accompanied by dance) were promoted in the presence of an audience, especially if it was the opposite sex. In contrast, unimodal displays (song without dance) were suppressed by audiences. Because birds directed the courtship dancing toward their partners (but not the audience), multimodal courtship displays are likely meant to advertise their current mating status to other cordon-bleus.

中文翻译：

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夫妻炫耀：观众在鸣禽中促进男性和女性多模式求爱的展示。

社交环境可以影响动物的交流。尽管通常认为相互求偶显示在男性和女性之间的私人交流中起作用，但我们提供了实验证据，表明它们在比以前认为的更广泛的社会环境中起作用。我们研究了受众群体对社交上一夫一妻制的蓝封顶警戒线的相互求爱的影响。该物种的特征是两性之间有明显的求爱：两性都唱歌，有时还会添加独特的舞蹈表演，看起来像人的踢踏舞。我们发现，在有观众的情况下，特别是在异性的情况下，男女双方都促进了多模式求爱表演（伴随舞蹈的歌曲演唱）。相反，单峰显示（无舞蹈歌曲）被观众压制。