Many vocalizing animals produce the discrete elements of their acoustic signals in a specific sequential order, but we know little about the biological relevance of this ordering. For that, we must characterize the degree by which individuals differ in how they organize their signals sequentially and relate these differences to variation in quality and fitness. In this study, we fulfilled these tasks in male collared flycatchers (Ficedula albicollis). We characterized the sequential order of syllables with a network analysis approach and studied the consistency of network variables on distinct time scales (within day, between days, and between years), and assessed their relationship with such quality indicators like age, body condition, arrival date, and fitness related proxies like survival to the next year and pairing success. We found that the syllables were associated nonrandomly with one another and both the frequency differences of consecutive syllables and the number of motif types were higher in the original than in randomized syllable sequences. Average degree and small-worldness showed considerable among-individual differences and decreasing repeatability with increasing time scale. Furthermore, we found relationships between male age and average degree among and within individuals. Accordingly, older males produce syllable sequences by using common syllables less often than younger individuals. However, the network variables showed no relationship with fitness-related variables. In conclusion, the sequential organization of birdsong has the potential to encode individual-specific characteristics, which thus could be used as signal in social interactions and thus potentially could be subject to sexual selection.

中文翻译：

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鸟鸣声的顺序组织：与个体素质和适应性的关系

许多发声动物会按特定的顺序产生声音信号的离散元素，但我们对该顺序的生物学相关性知之甚少。为此，我们必须描述个体在顺序组织信号方面的差异程度，并将这些差异与质量和适应性变化联系起来。在这项研究中，我们在雄领collar蝇（Ficedula albicollis）中完成了这些任务。）。我们使用网络分析方法对音节的顺序顺序进行了表征，并研究了不同时间尺度上（天，日间，年间和年间）网络变量的一致性，并评估了它们与诸如年龄，身体状况，到来等质量指标的关系。日期，以及与健身相关的代理，例如到明年生存和配对成功。我们发现音节彼此之间是非随机关联的，连续音节的频率差异和基序类型的数量在原始音节中均高于随机音节序列。平均程度和小世界表现出很大的个体差异，并且随着时间尺度的增加，重复性降低。此外，我们发现男性年龄与个人之间及内部平均程度之间的关系。因此，年龄较大的男性通过使用普通音节的频率比年轻个体少，从而产生音节序列。但是，网络变量显示与适应性相关的变量无关。总之，鸟鸣声的顺序组织有可能编码个体特有的特征，因此可以用作社交互动中的信号，因此有可能受到性选择的影响。