The Roles of Signature Whistle on Social Behavior of Bottlenose Dolphin

值得注意的是，海豚个体特有的标志性哨声经常被海豚使用。如前一份报告所述，从同一个人身上观察到了许多不同类型的特征哨。这些都是显着的签名哨声有很长的持续时间所发出的捕获动物。自由游泳动物发出的哨声持续时间短，方差差。不过，也可以分成几种。有一两种是经常使用的。频率的变化小于百分之几。使用频率越高，频率变异越小。这在口哨的开始是很了不起的。如果自由泳动物的特征哨是由哨声的开始组成的，则可以忽略个体的变化，因为自由泳动物的大多数特征哨是短而简单的。哨声的开头是用来互相联系的，但后面的部分似乎是另一种意思。阿马库萨观测区的特征哨声的种类与前文描述的该地区海豚数量的变化基本一致。这与用背鳍照片区分的海豚数量一致。信号呼叫的交换不仅在旅行时而且在停留时都被观察到，并且在停留时单位时间内的发生率比旅行时更频繁。似乎行进中的群体由熟悉的个体组成，并且与观察区域的其他群体在声学上隔离。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.