论文标题：Sound transmission in a bamboo forest and its implications for information transfer in giant panda (Ailuropoda melanoleuca) bleats

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作者：Benjamin D. Charlton, Megan A. Owen, Jennifer L. Keating, Meghan S. Martin-Wintle, Hemin Zhang & Ronald R. Swaisgood

发表时间：2018/09/25

数字识别码：10.1038/s41598-018-31155-5

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《app手机版》近日发表的一项研究Sound transmission in a bamboo forest and its implications for information transfer in giant panda (Ailuropoda melanoleuca) bleats表明，大熊猫（Ailuropoda melanoleuca）叫声所传递的身份信息最远可达20米，性别信息的传递距离最远可达10米。叫声中蕴含的个体身份和性别线索或许能为熊猫提供重要信息，让它们能够在可视度不佳的浓密竹林中实现近距离互动。

图1：来源：Pixabay

大熊猫是一种独居动物。因此，有效交流对辨认同伴位置、躲避有潜在攻击性的竞争者来说可能很重要。众所周知，雄性大熊猫遇到发情期的雌性大熊猫后发出高频率的叫声，这说明叫声对熊猫协调交配活动很重要。不过如果大熊猫的叫声无法在它们生活的竹林中稳定传播，叫声中所携带的信息就无法发挥作用。

美国圣地亚哥野生动物园保育研究所的Benjamin Charlton及同事回放了100段叫声（来自10只成年大熊猫，每只10个叫声），并在离回放喇叭10米、20米、30米和40米处分别对这些声音进行录音。回放和录音均在美国加州圣地亚哥野生动物园的混合竹林中进行，这里的竹子密度与大熊猫的天然栖息地相似。结果显示，在竹林中大熊猫叫声的声学结构可被同类识别的距离最长可达20米，不过距离超过10米大熊猫就无法辨清声音主人的性别了。

图2：大熊猫叫声的波形和频谱图显示对 （a）强度等值线（b）F0曲线和（c）频谱的声学测量。

图源：Charlton 等

通过确定大熊猫对交配相关叫声的可能的识别范围，这项研究为大熊猫的繁育策略提供了新的启示。

摘要：Although mammal vocalisations signal attributes about the caller that are important in a range of contexts, relatively few studies have investigated the transmission of specific types of information encoded in mammal calls. In this study we broadcast and re-recorded giant panda bleats in a bamboo plantation, to assess the stability of individuality and sex differences in these calls over distance, and determine how the acoustic structure of giant panda bleats degrades in this species’ typical environment. Our results indicate that vocal recognition of the caller’s identity and sex is not likely to be possible when the distance between the vocaliser and receiver exceeds 20 m and 10 m, respectively. Further analysis revealed that the F0 contour of bleats was subject to high structural degradation as it propagated through the bamboo canopy, making the measurement of mean F0 and F0 modulation characteristics highly unreliable at distances exceeding 10 m. The most stable acoustic features of bleats in the bamboo forest environment (lowest % variation) were the upper formants and overall formant spacing. The analysis of amplitude attenuation revealed that the fifth and sixth formant are more prone to decay than the other frequency components of bleats, however, the fifth formant still remained the most prominent and persistent frequency component over distance. Paired with previous studies, these results show that giant panda bleats have the potential to signal the caller’s identity at distances of up to 20 m and reliably transmit sex differences up to 10 m from the caller, and suggest that information encoded by F0 modulation in bleats could only be functionally relevant during close-range interactions in this species’ natural environment.

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