Social context and noise affect within and between-male song adjustments in a common passerine

Across populations, animals that inhabit areas with high anthropogenic noise produce vocalizations that differ from those inhabiting less noisy environments. Such patterns may be due to individuals rapidly adjusting their songs in response to changing noise, but individual variation is seldom explored. We tested the hypothesis that male house wrens (Troglodytes aedon) immediately adjust their songs according to changing noise, and that social context further modifies responses. We recorded songs, quantified noise, and defined social context within pairs as female fertile status and between males as number of conspecific neighbors. We used a reaction norm approach to compare song trait intercepts (between-male effects) and slopes (within-male effects) as a function of noise. Individuals immediately adjusted song duration in response to changing noise. How they achieved adjustments varied: some sang shorter and others longer songs with greater noise, and individuals varied in the extent t...

跨种群层面而言，栖息于人为噪声较高区域的动物，其鸣叫声与栖息于低噪声环境的同类存在显著差异。此类模式可能源于个体针对噪声变化快速调整鸣唱，但个体间的差异鲜有研究探讨。我们针对雄性家鹪鹩（Troglodytes aedon）验证了两项假说：其一，它们会根据噪声变化即时调整鸣唱；其二，社会背景会进一步调节其响应行为。本研究录制了鸣唱信号，量化了环境噪声水平，并将配对内的社会背景定义为雌性的可育状态，将雄性间的社会背景定义为同种邻鸟的数量。我们采用反应规范（reaction norm）分析方法，以噪声水平为自变量，对比分析鸣唱特征的截距（雄性间效应）与斜率（雄性内效应）。结果显示，个体确实会针对噪声变化即时调整鸣唱时长。个体达成调整的方式存在异质性：部分个体在噪声升高时缩短鸣唱时长，另一些则延长鸣唱时长，且个体间的调整幅度存在差异……