Hart Vlastimil, Policht Richard, Jandák Vojtěch, Brothánek Marek, Burda Hynek
Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Praha, Czech Republic.
Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czech Republic.
PeerJ. 2020 Jul 8;8:e9189. doi: 10.7717/peerj.9189. eCollection 2020.
Only a few bird species are known to produce low-frequency vocalizations. We analyzed the display vocalizations of Western Capercaillie males kept in breeding centers and identified harmonically structured signals with a fundamental frequency of 28.7 ± 1.2 Hz (25.6-31.6 Hz). These low-frequency components temporally overlap with the Whetting phase (96% of its duration) and they significantly contribute to the distinct vocal expression between individuals. The resulting model of discrimination analysis classified 67.6% vocalizations (63%, cross-validated result) correctly to the specific individual in comparison to the probability by chance of 12.5%. We discuss a possible function of low-frequency components that remains unclear. The occurrence of such low frequencies is surprising as this grouse is substantially smaller than cassowaries (Southern cassowary and Dwarf cassowary ) , the species that produces similarly low frequencies. Because these low frequency components temporarily overlap with the Whetting phase, they are hardly audible from a distance larger than several meters.
已知只有少数鸟类会发出低频叫声。我们分析了饲养在繁殖中心的西方松鸡雄性的展示叫声，并识别出了基频为28.7±1.2赫兹（25.6 - 31.6赫兹）的谐波结构信号。这些低频成分在时间上与磨喙阶段（占其持续时间的96%）重叠，并且它们对个体之间独特的声音表达有显著贡献。与随机概率12.5%相比，由此产生的判别分析模型将67.6%的叫声（交叉验证结果为63%）正确分类到特定个体。我们讨论了低频成分的一种可能功能，但其仍不明确。这种低频的出现令人惊讶，因为这种松鸡比发出类似低频的食火鸡（南方食火鸡和侏食火鸡）小得多。由于这些低频成分在时间上与磨喙阶段重叠，在距离大于几米时几乎听不到。
