The Roles of Signature Whistle on Social Behavior of Bottlenose Dolphin

研究发现，宽吻海豚经常使用个体特有的口哨声。如前所述，在同一个体中观察到签名哨子的许多变异类型。捕获的动物发出的标志性哨声持续时间很长。自由游动的动物发出的口哨声持续时间短，变异性差。然而，有可能将它们收集为几种类型。有一种或两种类型被频繁使用。频率的变化小于几个百分点。使用频率越高，频率变化越小。在哨声开始的时候，这是值得注意的。如果自由游泳动物的标志性哨声是由哨声的开头组成的，那么可以忽略个体的变化，因为自由游泳动物的大部分标志性哨声都是简短的。哨子的开头是用来互相联系的，但是哨子的后面部分似乎是用来表达另一种意思。天草观测区域的特征哨声种类与前文描述的该区域海豚数量变化基本一致。这与用背鳍照片辨别出的海豚数量相符。不仅在旅行时，而且在停留时也观察到签名叫声的交换，停留时单位时间的频率比旅行时要高。在旅行的群体似乎是由熟悉的个体组成的，并且在声音上与观察区域的另一组隔离。在逗留期间，他们不仅在视觉上，而且在听觉上与每个群体接触。

It is noticed that the signature whistle peculiar to individual is frequently utilizing by the bottlenose dolphins. As mentioned in the previous report, many variance types of the signature whistle were observed from the same individual. Those were remarkable on the signature whistles having long duration emitted by captured animals. The whistles emitted by free-swimming animals were short in duration and had poor variance. However, it was possible to collect those into a few types. One or two types were used very frequently. The variation of frequency was less than a few %. The higher the frequency of use was, the lower the frequency variation was. It was remarkable at the beginning of whistle. If the signature whistle of free-swimming animal was composed by the beginning of the whistle, it may be possible to disregard the variation in the individual, because the most of the signature whistle from the free-swimming animal is short and simple. The beginning of whistle is used for contact with each other, but it seems that the subsequent part of whistle is used for another meaning.The kinds of the signature whistle in the observation area of Amakusa are almost same with the variation of number of dolphins living in that area described in previous paper. This conforms well to the number of dolphin distinguished by photograph of dorsal fin.The exchange of the signature calls were observed at not only the traveling but also staying and the occurrence per unit time at staying is more frequent than that of traveling. It seems that the group at the traveling is composed by the familiar individuals and is isolated acoustically from the other group at the observation area. During the staying, they contact with each group not only visually but also acoustically.