Song

Abstract

The biological definition of song is a series of sounds that are repeated over and over. Although likely heard by sailors for millennia, the first recordings of humpback songs were made via US Navy hydrophones in the 1950s off Hawaii and Bermuda. Scientists first recognized these sounds in the 1960s as coming from humpback whales. Although whale song was introduced and has been virtually synonymous with the humpback whale, recent studies indicate that other species of baleen whales, including bowheads, blues, fins, and minkes, also repeat patterned sequences of sounds that fit the song definition. The humpback whale song is composed of a sequence of highly varied sounds ranging from high-pitched squeaks to midrange trumpeting and screeches to lower frequency ratchets and roars, and combinations of all these. This sequence is typically about 10 to15 min in duration, although it may range from 5 to 30 min. It is then repeated without a break. One of the more unique characteristics of the humpback song is that it gradually changes over time. Different sounds, and arrangements of sounds, form to create new phrases and themes. These are incorporated into the song gradually, while older patterns are lost. The change in the song display occurs in a collective or common way throughout a population of humpback whales. The similarity and collective change of the song may occur not only within one population of humpbacks, but between populations separated by thousands of kilometers. The function of the song has been the subject of much speculation. Much of this has revolved around proposals of the song as a male display that function to attract females, signal status to other males, or a combination of these. However, other suggestions include that the songs serve as a means to synchronize estrus, a spacing mechanism between males, a migratory beacon, and as sonar by males to find females.