Abstract：
The Cape fur seal (Arctocephalus pusillus pusillus) is one of the most colonial mammals, with colonies of up to hundreds of thousands of individuals during the breeding season. During the lactation period, mothers and pups are regularly separated as females undertake multi-day foraging trips at sea. Mothers and pups use a mutual vocal recognition system to reunite after separation. Such communication is highly constrained by both high background noise and risk of individual confusion owing to the density of seals. This study aimed to experimentally assess the acoustic features relevant for mother-pup vocal identification and the propagation properties of their calls. Playback experiments revealed that mother and pup individual vocal signatures rely on both temporal and frequency parameters: amplitude and frequency modulations, timbre and fundamental frequency (f0). This is more parameters than in any colonial species studied so far. The combinational use of acoustic features reinforces the concept that both environmental and social constraints may have acted as selective pressures on the individual vocal recognition systems. Theoretical propagation distances of mother and pup vocalisations were estimated to be below the range of distances at which mother-pup reunions can occur. This suggests that Cape fur seals may have strong abilities to extract vocal signals from the background noise, as previously demonstrated in the highly colonial king penguin. Investigating the transmission of information throughout the propagation of the signal as well as the ability of the receiving individual to decipher vocal signatures is crucial to understanding vocal recognition systems in the wild.
摘要：
海角海狗（Arctocaluspusilluspusillus）是最殖民地的哺乳动物之一，在繁殖季节，殖民地多达数十万人。在哺乳期,当雌性在海上进行多天的觅食旅行时，母亲和幼崽经常被分开。母亲和幼崽使用相互的声音识别系统在分离后团聚。由于密封的密度，高背景噪声和个人混淆的风险极大地限制了这种通信。这项研究旨在通过实验评估与母犬声音识别相关的声学特征及其通话的传播特性。回放实验表明，母亲和幼犬的个人声音特征依赖于时间和频率参数：振幅和频率调制，音色和基频（f0）。这比迄今为止研究的任何殖民地物种都要多。声学特征的组合使用加强了这样一个概念，即环境和社会约束都可能对单个声音识别系统产生选择性压力。据估计，母犬和幼犬发声的理论传播距离低于母犬团聚的距离范围。这表明海角海豹可能具有从背景噪声中提取声音信号的强大能力，正如先前在高度殖民的国王企鹅中所证明的那样。研究信息在整个信号传播过程中的传输以及接收个人破译声音签名的能力对于理解野外的声音识别系统至关重要。
