Why Do Whales Sing? Song, Mating and Communication
Whales sing mainly to communicate. Male humpback whales produce long, structured songs in breeding grounds, probably to attract mates and signal to rival males.
Whales sing mainly to communicate, and the best-studied case is the male humpback whale. In the breeding season males produce long, patterned songs that can last for many minutes or hours and repeat. The likeliest purposes are attracting females and signalling to rival males, though scientists do not agree on every function. Most whale sounds are not songs at all.
Which whales sing?
Scientists separate whale song from simpler calls. A call is a short sound with a clear meaning, such as contact between a mother and calf. Song is longer, has layers of structure and is repeated in sequence. Humpback whales are the clearest example. Because producing a long song takes energy, some researchers argue that singing shows a male's physical condition to others, though this idea is still being tested. Male blue and fin whales produce long, low-frequency repeated sounds that some researchers also call song.
A single humpback song can last 10 to 20 minutes or more, and singers repeat the whole sequence, sometimes for hours.
Toothed whales, such as dolphins and sperm whales, communicate mostly with whistles and clicks. Sperm whales produce short rhythmic patterns of clicks called codas, which are used in social contact.
How do whales make sound?
Baleen whales, including humpbacks, appear to make sound with the larynx, pushing air past the vocal folds. The sound then passes through the vocal tract, which shapes and amplifies it. Toothed whales make clicks and whistles in the nasal passages, using structures called phonic lips, and they focus their clicks through a fatty organ in the forehead called the melon.
Sound moves more than four times faster in seawater than in air, and low-frequency sound can travel very far in the ocean. Deep water has a sound channel, described in the deep ocean, where the speed of sound is lowest, and it can carry low sounds across thousands of kilometres. Sound is a pressure wave, the same kind of motion a loudspeaker produces, and a whale song is built to travel far. The pitch and tone of a sound depend on its harmonics, explained in the harmonic series and overtones.
What is the song for?
Several hypotheses have been proposed, and they are not mutually exclusive.
| Hypothesis | Main evidence | Status |
|---|---|---|
| Attracting mates | Singing peaks in breeding grounds, during the mating season | Widely supported, not proven |
| Rivalry between males | Males sing close together and may respond to one another | Supported, debated |
| Group identity | Sperm whale codas differ between social groups | Studied in toothed whales |
Humpback songs follow rules. A song is built from units, grouped into phrases and themes, and sung in a set order. All males in one population sing the same song at a given time, and the song changes gradually over a few seasons. Its function is still the subject of active study, and that is part of the appeal of the topic.
How do songs change over time?
Recordings from different ocean basins show that separate populations sing different songs. In 1971 Roger Payne and Scott McVay published recordings showing that humpback song changed from year to year, and that the males in a population converged on the same new version. Songs also spread across ocean basins, changing as they travel. Learned, group-wide vocal traditions like this are unusual in animals, and they are one reason whale song is studied as a form of culture. Evolutionary pressure acts on signals like these, as in natural selection more generally.
What threatens whale song?
Human noise can interfere with communication. Shipping noise has grown with global trade, and much of it overlaps the low frequencies that many baleen whales use. Shipping, seismic surveys that use airguns, and military sonar add sound to the ocean. Some studies have documented changes in calling behaviour and a reduced communication range in whales exposed to noise. How much noise harms whale populations is still being studied, and the effects differ between species.
Tags
animals bioacoustics biology communication sound
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