National Marine Mammal Foundation, 2240 Shelter Island Dr, Suite 200, San Diego, CA 92106, USA.
National Marine Mammal Foundation, 2240 Shelter Island Dr, Suite 200, San Diego, CA 92106, USA.
Behav Processes. 2022 Jan;194:104561. doi: 10.1016/j.beproc.2021.104561. Epub 2021 Nov 25.
Bottlenose dolphin signature whistles are characterized by distinctive frequency modulation over time. The stable frequency contours of these whistles broadcast individual identity information. Little is known however, about whether or not the amplitude contour is also stereotyped. Here, we examined the relative amplitude-time contour of signature whistle emissions from eight bottlenose dolphins (Tursiops truncatus) in the U.S. Navy Marine Mammal Program (MMP) in San Diego, CA. The results suggested that unlike the stable frequency-time contour, the amplitude-time contour of signature whistles were largely non-stereotyped, characterized by large variability across multiple whistle emissions. Relative amplitude was negatively related to log peak frequency, with more energy focused in the lower frequency bands. This trend was consistent over all eight dolphins despite having quite different signature whistle contours. This relationship led to the amplitude contours being slightly more stereotyped within than between dolphins. We propose that amplitude across signature whistle emissions may serve as an avenue for encoding additional communicative information. We encourage future studies to incorporate analyses of amplitude contours in addition to frequency contours of signature whistles in order to begin to understand what role it may play in the dolphin communication system.
宽吻海豚的标志性口哨声以随时间变化的独特频率调制为特征。这些口哨声稳定的频率轮廓可广播个体身份信息。然而，人们对于幅度轮廓是否也具有固定模式知之甚少。在这里，我们检查了来自加利福尼亚州圣地亚哥的美国海军海洋哺乳动物计划（MMP）中的 8 只宽吻海豚（Tursiops truncatus）的标志性口哨声的相对幅度-时间轮廓。结果表明，与稳定的频率-时间轮廓不同，标志性口哨声的幅度-时间轮廓在很大程度上是非固定模式的，其特征是在多个口哨声发射中具有很大的可变性。相对幅度与对数峰值频率呈负相关，更多的能量集中在较低的频带中。尽管这 8 只海豚的标志性口哨声轮廓有很大差异，但这种趋势在所有海豚中都是一致的。这种关系导致幅度轮廓在海豚内部比在海豚之间稍微更固定。我们提出，在标志性口哨声发射中，幅度可能是编码附加通信信息的一种途径。我们鼓励未来的研究除了标志性口哨声的频率轮廓外，还纳入幅度轮廓的分析，以便开始了解它在海豚通信系统中可能发挥的作用。
