The Roles of Signature Whistle on Social Behavior of Bottlenose Dolphin

点击翻译按钮获取中文摘要

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.