Large Scale Changes over 19 Years in Songs of Humpback Whales in Bermuda


Laboratory of Ornithology, Cornell University, Ithaca, N.Y. 14850, U.S.A.

World Wildlife Fund — US, 1601 Connecticut Ave. NW, Washington, DC 20009, U.S.A.


Abstract and Summary

163 songs of humpback whales (Megaptera novaeangliae) recorded near Bermuda during April and May of 13 years between 1957 and 1975 have been analysed as continuous sound spectrograms and compared. In each year's sample, all whales were singing basically the same song. However, the song was changing conspicuously and progressively with time so that songs separated by a number of years were very different in content. All the songs showed basic structural similarities so that it is possible to define a song form which characterizes songs from many years. We present some basic characteristics of the song form and consider the nature and extent of changes in content as a function of time. An analysis of the songs sung by groups of whales shows that normal singing continues even when whales are close enough, presumably, to hear each other. Such analysis demonstrates inter– and intra– individual variability, none of which is as great as the variation between songs of consecutive years. We do not understand the significance of changing songs. We know of no other non-human animal for which such dramatic non-reversing changes appear in the display pattern of an entire population as part of their normal behavior.


In 13 Jahren (1957–1975) wurden bei Bermuda, jeweils von April bis Mai, 163 Gesänge von Buckelwalen aufgenommen und analysiert. In jedem Jahr sangen alle Wale im Grunde denselben Gesang. Über die Jahre änderten sich diese Gesänge deutlich; Gesänge, zwischen denen mehrere Jahre lagen, waren deutlich verschieden.

Alle Gesänge haben den gleichen Grundaufbau, an dem sich Änderungen über die Zeit aufzeigen lassen. In Walgruppen treten Gesänge auch dann auf, wenn die Tiere in Hörweite voneinander sind. Intra– und interindividuelle Unterschiede waren kleiner als die Unterschiede zwischen aufeinanderfolgenden Jahren.

Die Bedeutung der Gesangsänderung ist unbekannt. Von keinem anderen Tier ist solche Weiterentwicklung eines Signalverhaltens einer ganzen Population berichtet worden.