Differential response of humpback whales, Megaptera novaeangliae, to playback of song or social sounds

Playback experiments were performed with wild humpback whales, Megaptera novaeangliae, during their breeding and calving season off the island of Maui, Hawaii. Singing whales usually stopped singing upon playback of either songs recorded from lone whales or social sounds recorded from groups of five to eight humpback whales in which males were fighting, probably for access to a female in the group. Three out of four lone singers and six of the eight groups of one or two adults exposed to social sounds charged the playback boat, but the two cows with calves and two groups of three of more adults exposed to social sounds moved away. Of the 16 groups of whales exposed to playback of song, 14 groups moved away. These responses are very similar to those evoked by singing whales or the large active groups from which the social sounds were recorded. The playback experiments thus support the conclusion that the songs and social sounds of humpback whales mediate the responses of approach or avoidance that these whales make to singing whales or large groups in which aggressive behavior is occuring.