Directionality in the whistles of Hawaiian spinner dolphins (Stenella longirostris):: A signal feature to cue direction of movement?
Directionality in the whistles of Hawaiian spinner dolphins (Stenella longirostris):: A signal feature to cue direction of movement?
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DOI：
10.1111/j.1748-7692.2003.tb01107.x
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发表时间：
2003-04-01
影响因子：
2.3
通讯作者：
Au, WWL
中科院分区：
文献类型：
--
作者：
Lammers, MO;Au, WWL
海豚发出调频（FM）哨声，被认为可以促进群体成员之间行为的同步和协调。哨子在这方面是如何使用的，人们仍然知之甚少。一种可能性是哨声具有方向性，从而将信号发出者的方向和运动方向传达给附近的听者。为了探索这种可能性，使用拖曳的三水听器线阵列获得了自由放养的夏威夷旋海豚（Stenella longirortris）的哨声，并检查了方向性的存在。与阵列一起或朝着阵列移动的动物产生的哨声的估计源电平和谐波含量都大于向前或远离阵列的动物。此外，在距离11.5 m的三个水听器上，靠近阵列（20 m内）的动物产生的信号接收方式不同。这些差异比单纯的传输损耗差异所预期的要大。结果表明，哨子的传输模式存在方向性。为了推断这种指向性的形式，在假定海豚的声源近似为圆形活塞换能器的基础上，建立了一个理论哨声波束模式（Au 1993）。由此产生的波束表明，随着频率的增加，旋海豚哨声的方向性越来越强，尤其是在谐波方面。因此，口哨的方向依赖的谐波结构提供了一个潜在的线索，聆听动物可以通过解释来推断信号者的运动方向。谐波存在于许多海豚物种的口哨声中，可能代表了一种内在的信号设计特征，可以促进动物之间的协调。
Dolphins produce frequency modulated (FM) whistles that are thought to promote the synchrony and coordination of behavior between members of a group. How whistles are used in this regard remains poorly understood. One possibility is that whistles have directionality and thereby convey the orientation and direction of movement of the signaler to nearby listeners. To explore this possibility, whistles from free-ranging Hawaiian spinner dolphins (Stenella longirortris) were obtained using a towed, three-hydrophone line array and examined for the presence of directionality. Both the estimated source level and harmonic content of whistles produced by animals traveling with or toward the array were greater than those of animals moving ahead or away from it. In addition, signals produced by animals near the array (within 20 m) were received differently on the three hydrophones spaced 11.5 m apart. These differences were greater than would be expected from transmission loss disparities alone. The results indicate that directivity is present in the transmission pattern of whistles. To infer the form of this directivity, a theoretical whistle beam pattern was established based on the assumption that the dolphin's sound source is approximated by a circular piston transducer (Au 1993). The resulting beam indicates that spinner dolphin whistles become increasingly directional with frequency, especially with respect to harmonics. The orientation-dependent harmonic structure of whistles thus presents a potential cue that listening animals could interpret to infer the direction of movement of signalers. Harmonics are present in the whistles of many dolphin species and may represent an inherent signal design feature that promotes coordination between animals.