Estimating the Active Space of Male Koala Bellows: Propagation of Cues to Size and Identity in a Eucalyptus Forest
Estimating the Active Space of Male Koala Bellows: Propagation of Cues to Size and Identity in a Eucalyptus Forest
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DOI：
10.1371/journal.pone.0045420
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发表时间：
2012-09-20
期刊：
影响因子：
3.7
通讯作者：
Fitch, W. Tecumseh
中科院分区：
文献类型：
--
作者：
Charlton, Benjamin D.;Reby, David;Fitch, W. Tecumseh
研究距离的增加如何影响声音信号的信息内容是确定特定物种声音通信系统活动空间的基础。在目前的研究中，我们播放了桉树森林中的雄性考拉风箱，以确定雄性考拉风箱的个体分类在距离上变得不那么准确的程度，并量化风箱的个体独特的声学特征和与大小相关的信息如何随着距离而退化。我们的研究结果表明，来自线性预测编码的波纹管的共振峰频率可以用来分类呼叫雄性考拉在1-50米的距离。进一步的分析表明，上共振峰频率和共振峰频率间隔是雄性风箱在桉树冠层中传播时最稳定的声学特征。综上所述，这些研究结果表明，考拉可以识别已知的个人在距离达50米，并表示，他们应该参加的变化，在上共振峰频率和共振峰频率间隔时，评估呼叫者的身份。此外，由于共振峰频率间隔也是一个线索，男性的身体大小在这个物种和它的变化随着距离保持非常低的记录个体间的变化相比，我们建议，男性考拉仍然会可靠地分类为小型，中型或大型接收器在距离高达150米。
Examining how increasing distance affects the information content of vocal signals is fundamental for determining the active space of a given species' vocal communication system. In the current study we played back male koala bellows in a Eucalyptus forest to determine the extent that individual classification of male koala bellows becomes less accurate over distance, and also to quantify how individually distinctive acoustic features of bellows and size-related information degrade over distance. Our results show that the formant frequencies of bellows derived from Linear Predictive Coding can be used to classify calls to male koalas over distances of 1-50 m. Further analysis revealed that the upper formant frequencies and formant frequency spacing were the most stable acoustic features of male bellows as they propagated through the Eucalyptus canopy. Taken together these findings suggest that koalas could recognise known individuals at distances of up to 50 m and indicate that they should attend to variation in the upper formant frequencies and formant frequency spacing when assessing the identity of callers. Furthermore, since the formant frequency spacing is also a cue to male body size in this species and its variation over distance remained very low compared to documented inter-individual variation, we suggest that male koalas would still be reliably classified as small, medium or large by receivers at distances of up to 150 m.