Favaro Livio, Ozella Laura, Pessani Daniela
Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy.
PLoS One. 2014 Jul 30;9(7):e103460. doi: 10.1371/journal.pone.0103460. eCollection 2014.
The African Penguin (Spheniscus demersus) is a highly social and vocal seabird. However, currently available descriptions of the vocal repertoire of African Penguin are mostly limited to basic descriptions of calls. Here we provide, for the first time, a detailed description of the vocal behaviour of this species by collecting audio and video recordings from a large captive colony. We combine visual examinations of spectrograms with spectral and temporal acoustic analyses to determine vocal categories. Moreover, we used a principal component analysis, followed by signal classification with a discriminant function analysis, for statistical validation of the vocalisation types. In addition, we identified the behavioural contexts in which calls were uttered. The results show that four basic vocalisations can be found in the vocal repertoire of adult African Penguin, namely a contact call emitted by isolated birds, an agonistic call used in aggressive interactions, an ecstatic display song uttered by single birds, and a mutual display song vocalised by pairs, at their nests. Moreover, we identified two distinct vocalisations interpreted as begging calls by nesting chicks (begging peep) and unweaned juveniles (begging moan). Finally, we discussed the importance of specific acoustic parameters in classifying calls and the possible use of the source-filter theory of vocal production to study penguin vocalisations.
非洲企鹅（Spheniscus demersus）是一种高度群居且善于鸣叫的海鸟。然而，目前关于非洲企鹅发声库的描述大多仅限于对叫声的基本描述。在此，我们首次通过从一个大型圈养群体中收集音频和视频记录，对该物种的发声行为进行了详细描述。我们将频谱图的视觉检查与频谱和时间声学分析相结合，以确定发声类别。此外，我们使用主成分分析，随后通过判别函数分析进行信号分类，对发声类型进行统计验证。另外，我们确定了发出叫声的行为背景。结果表明，成年非洲企鹅的发声库中有四种基本发声，即独居鸟类发出的联络叫声、攻击性互动中使用的争斗叫声、单只鸟发出的狂喜展示歌声以及成对鸟在巢中发出的相互展示歌声。此外，我们还识别出两种不同的发声，被解释为育雏幼鸟（乞食啁啾）和未断奶幼鸟（乞食呻吟）的乞食叫声。最后，我们讨论了特定声学参数在叫声分类中的重要性，以及发声产生的源 - 滤波器理论在研究企鹅发声方面的可能应用。
