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Humpback Whale Song

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Humpback Whale Song

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The humpback whale song is one of the most complex, non-human,
acoustic displays in the animal kingdom.

 

Male humpback whales emit a complex series of loud sounds over and over known as song. Singing is usually heard during the breeding season, but also occurs during migration and in late summer and fall feeding areas. Although likely heard by sailors for centuries, the first recordings of humpback songs were made via U.S. Navy ships in the late 1950s off Hawaii and Bermuda. Scientists first recognized these sounds as coming from humpback whales in the 1960s, and the first technical description of humpback whale song was published in Science in 1971 by Dr. Roger Payne and Scott McVay.

Since then, the general structure of the song as well as the basic characteristics of singers have been described by scientists. These characteristics, combined with limited observations of singing whales have led to several ideas as to the function or role of the humpback whale song on the breeding grounds. Our research tests these ideas through intensive observation and measurement of the behavior of singers, and their interactions with other whales.

Structure of the Song

The song has a predictable structure with a series of sounds (units), repeated over time in patterns (phrases), with each phrase repeated several times to comprise a "theme".

A typical song is then made up of 5-7 themes that are usually repeated in a sequential order. A song typically lasts 8-15 minutes (although it may range from 5-30 minutes), and then is repeated over and over in a song session that may last several hours.

The sounds that comprise a humpback song are varied and can range from high-pitched squeaks to lower frequency roars and ratchets.

Humpback Whale Song is Constantly Changing

A striking feature of the song is that it gradually changes or evolves over time. Each year, different sounds and arrangements of sounds form to create new phrases or themes. These changes are slowly incorporated into the song, while some older patterns are lost completely. The song apparently changes as it is being sung. The change in the song display seems to occur in a collective or common way throughout the population. Usually after a period of several years, the song is virtually unrecognizable from the original version. In some cases, however, the song has completely changed in just two years!

Despite the constantly changing nature of the song, all singers in a population sing essentially the same version at any one time. In fact, all the singers in the North Pacific (that is, whales in Japan, Hawaii, Mexico and the Philippines) separated by thousands of kilometers sing essentially the same version of a song at any one time. The songs of humpbacks may be similar across entire ocean basins like the North Pacific Ocean, yet different in separate oceans. Humpback whales in the South Pacific, for instance, have a different song from humpback whales in the North Pacific Ocean.

The explanation for the collective change of the song, especially over such vast distances, is currently unknown.

Characteristics of Singers

Humpback whales sing primarily in winter breeding grounds, although some singing begins in the late summer on the feeding grounds. Singing is also regularly heard during the migration from summer to winter grounds.

The evidence to date indicates that only male humpback whales sing. Photographs of the genital region and DNA sampling taken from skin samples have determined the gender of singers. Singers are usually, but not always, alone. At times, male singers may also accompany a female with a calf.

Often the singer is relatively stationary, staying in one geographical location for extended periods of time. During these stationary periods, singing humpback whales often hang in an upside down, head-down, tail-up position, approximately 15-30 meters below the surface. The singer will maintain this position until it surfaces to breathe and then immediately resumes this position after diving.

At other times, however, singers will steadily travel while singing and may move tens, if not hundreds of kilometers during a song session.

Interactions with Other Whales

Singers will sing until one of two things happen:

• (1) they are joined by another lone adult male called a joiner;
• (2) the singer stops singing without any close approach by another male and then rushes to approach or join a passing group of whales, often with a potentially breeding female included within the group.

When a humpback whale singer is approached and joined by another lone male, the interactions are usually relatively short ranging from a single pass to rolling, tail lobs, or breaches by one or both animals. Often the pair splits again after a few minutes. One or the other may start singing again shortly after the interaction.

Why Do Humpback Whales Sing?

Why whales sing is an intriguing and complex question. There are several ideas or hypotheses about the social function of song. The dominant hypotheses have viewed the song as a sexual display, with much emphasis on the notion that the song is primarily a display to attract females and that the song changes as a result of female choice. Often attached to this is the idea that the song also serves notice that the singer is prepared to fight. However, our research strongly suggests that the songs function to facilitate social interactions between adult males, with no evidence of a female response to date.

Other suggestions on the function(s) of humpback whale song include: 1) a physiological inducement to synchronize estrus in females; 2) or as an orientational display that acts as a migratory beacon, a male spacing mechanism, and/or a form of sonar to locate females.

Conservatively, the song is a communication from male humpbacks during the breeding season. It almost certainly provides the location of the singer, and by association the entire herd, and signals that reproductive activity is underway. The song also likely broadcasts information about the individual singer, but what information is communicated and who the recipient is remains unknown.

Portions of the above have been excerpted from "The Song" by Jim Darling in Encyclopedia of Marine Mammals (edited by W.F. Perrin, B. Würsig, and H.G.M. Thewissen, 2002)

To listen to humpback whales in Hawaii during the winter (January to April), log on to The Whalesong Project.