Whale vocalization

The word "song" is used to describe the pattern of regular and predictable sounds made by some species of whales, notably the humpback whale. This is included with or in comparison with music, and male humpback whales have been described as "inveterate composers" of songs that are "'strikingly similar' to human musical traditions".^[3] It has been suggested that humpback songs communicate male fitness to female whales.^[4]

Types and purpose of vocalization

While the complex sounds of the humpback whale (and some blue whales) are believed to be primarily used in sexual selection,^[5] there are simpler sounds that are created by other species of whales that have an alternative use and are used all year round.^{[citation needed]} Whale watchers have watched mother whales lift their young towards the surface in a playful motion, while making a noise that resembles cooing in humans.^[6] This cooing-like noise made by whales seems designed to relax their young^[6] and is one of several distinct everyday noises whales are known to make. Unlike some fish such as sharks, a toothed whale's sense of smell is absent, causing them to rely heavily on echolocation, both for hunting prey and for navigating the ocean under darkness.^{[citation needed]} This requires the whales to produce noise year round to ensure they are able to navigate around any obstacles they may face such as sunken ships or other animals.^{[citation needed]}

It has also been proven that whales are extremely social creatures. The noises that are made throughout the entire year (the main sounds being whistles, clicks, and pulsed calls) are used to communicate with other members of their pod.^[7] Each sound a whale makes could mean something different. The clicking noises whales make are used for navigation.^[7]   

The question of whether whales sometimes sing purely for aesthetic enjoyment, personal satisfaction, or 'for art's sake', is considered by some to be "an untestable question".^[8]

Song of the humpback whale

Humpback Whale Song

Recording of humpback whales singing.

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The humpback whale produces a series of repetitious sounds at varying frequencies known as whale song. Marine biologist Philip Clapham describes the song as "probably the most complex in the animal kingdom."^[9]

Male humpback whales perform these vocalizations often during the mating season, and so it is believed the purpose of songs is to aid mate selection.^[10]

Interest in whale song was aroused by researchers

All the whales in an area sing virtually the same song at any point in time and the song is constantly and slowly evolving over time.^[citation needed] For example, over the course of a month a particular unit that started as an upsweep (increasing in frequency) might slowly flatten to become a constant note.^[10] Another unit may get steadily louder. The pace of evolution of a whale's song also changes—some years the song may change quite rapidly, whereas in other years little variation may be recorded.^[10]

Idealized schematic of the song of a humpback whale.
Redrawn from Payne, et al. (1983)

Whales occupying the same geographical areas (which can be as large as entire ocean basins) tend to sing similar songs, with only slight variations. Whales from non-overlapping regions sing entirely different songs.^[10]

As the song evolves, it appears that old patterns are not revisited.^[10] An analysis of 19 years of whale songs found that while general patterns in song could be spotted, the same combination never recurred.^{[citation needed]}

Humpback whales may also make stand-alone sounds that do not form part of a song, particularly during courtship rituals.^[14] Finally, humpbacks make a third class of sound called the feeding call.^{[citation needed]} This is a long sound (5 to 10 s duration) of near constant frequency. Humpbacks generally feed cooperatively by gathering in groups, swimming underneath shoals of fish and all lunging up vertically through the fish and out of the water together. Prior to these lunges, whales make their feeding call. The exact purpose of the call is not known.

Some scientists have proposed that humpback whale songs may serve an echolocative purpose,^[15] but this has been subject to disagreement.^[16]

Other whale sounds

Humpback whales have also been found to make a range of other social sounds to communicate such as "grunts", "groans", "thwops", "snorts" and "barks".^[17]

In 2009, researchers found that blue whale song has been deepening in its tonal frequency since the 1960s.^[18] While noise pollution has increased ambient ocean noise by over 12 decibels since the mid-20th century, researcher Mark McDonald indicated that higher pitches would be expected if the whales were straining to be heard.^[19]

Killer whales have been observed to produce long range calls that are stereotyped and high frequency travelling distances from 10–16 km (6.2–9.9 mi) as well as short range calls that can travel distances from 5–9 km (3.1–5.6 mi). Short range calls are reported during social and resting periods while long range are more commonly reported during foraging and feeding.^[20]

Most other whales and dolphins produce sounds of varying degrees of complexity. Of particular interest is the

It was previously thought that most baleen whales make sounds at about 15–20 hertz.^[23] However, a team of marine biologists, led by Mary Ann Daher of the Woods Hole Oceanographic Institution, reported in New Scientist in December 2004 that they had been tracking a whale in the North Pacific for 12 years that was "singing" at 52 Hz. Scientists have been unable to explain this phenomenon. 52 Hz is a very low sound, it is audible through human ears as a low moaning sound.^[24] It was not expected that this whale was a new species, more so this whale indicated that a currently known species potentially has a much wider vocal range than previously thought.^[23] There is disagreement in the scientific community regarding the uniqueness of the whale's vocalization and whether it is a member of a hybrid whale such as the well documented blue and fin whale hybrids.

Mechanisms of sound production

Whistles are used for communication. Four- to six-month-old calves develop unique sounds that they use most frequently throughout their lives. Such "signature whistles" are distinctive to the individual and may serve as a form of identification among other odontocetes.[26] Though a large pod of dolphins will produce a wide range of different noises, very little is known about the meaning of the sound. Frankel quotes one researcher who says listening to a school of odontocetes is like listening to a group of children at a school playground.^[10]

The multiple sounds odontocetes make are produced by passing air through a structure in the head called the phonic lips.

The sperm whale's vocalizations are all based on clicking, described in four types: the usual echolocation, creaks, codas, and slow clicks.^[31] The most distinctive vocalizations are codas, which are short rhythmic sequences of clicks, mostly numbering 3–12 clicks, in stereotyped patterns.^[32][31] They are the result of vocal learning within a stable social group.^[33] Some codas express clan identity, and denote different patterns of travel, foraging, and socializing or avoidance among clans.^[34][35] As “arbitrary traits that function as reliable indicators of cultural group membership,” clan identity codas act as symbolic markers that modulate interactions between individuals.^[36]

Individual identity in sperm whale vocalizations is an ongoing scientific issue, however. A distinction needs to be made between cues and signals. Human acoustic tools can distinguish individual whales by analyzing micro-characteristics of their vocalizations, and the whales can probably do the same. This does not prove that the whales deliberately use some vocalizations to signal individual identity in the manner of the signature whistles that bottlenose dolphins use as individual labels.^[33][36]

Mysticete whales

Mysticetes do not have phonic lip structure. Instead, they have a larynx that appears to play a role in sound production, as it has vocal folds (vocal "cord") homologs in the U-shaped fold supported by arytenoid cartilages.^[37] Whales do not have to exhale in order to produce sound, as they capture the air in a laryngeal sac. It is likely that they recycle air from this sac back to the lungs for the next vocalization.^[37] They do not have bony cranial sinuses, but there is a pterygoid air sac. Its role in sound production is unclear (perhaps resonance?), but most likely it is for hearing, as it appears to preserve an airspace at depth around the ear ossicles.^[38]

Vocal plasticity and acoustic behavior

There are at least nine separate blue whale acoustic populations worldwide.^[39] Over the last 50 years blue whales have changed the way they are singing. Calls are progressively getting lower in frequency. For example, the Australian pygmy blue whales are decreasing their mean call frequency rate at approximately 0.35 Hz/year.^[40]

The migration patterns of blue whales remain unclear. Some populations appear to be resident in habitats of year-round high productivity in some years,^[41] while others undertake long migrations to high-latitude feeding grounds, but the extent of migrations and the components of the populations that undertake them are poorly known.^[42]

Sound levels

The frequency of baleen whale sounds ranges from 10 Hz to 31 kHz.^[43] A list of typical levels is shown in the table below.

Source	Broadband source level (dB re 1 ${\displaystyle \mu }$Pa at 1m)[44]
Fin whale moans	155–186
Blue whale moans	155–188
Gray whale moans	142–185
Bowhead whale tonals, moans and song	128–189

Human interaction

Researchers use hydrophones (often adapted from their original military use in tracking submarines) to ascertain the exact location of the origin of whale noises.^{[citation needed]} Their methods also allow them to detect how far through an ocean a sound travels.^{[citation needed]} Research by Dr. Christopher Clark of Cornell University conducted using military data showed that whale noises travel for thousands of kilometres.^[45] As well as providing information about song production, the data allows researchers to follow the migratory path of whales throughout the "singing" (mating) season. An important finding is that whales, in a process called the Lombard effect, adjust their song to compensate for background noise pollution.^[46]

Moreover, there is evidence that blue whales stop producing foraging D calls once a mid-frequency sonar is activated, even though the sonar frequency range (1–8 kHz) far exceeds their sound production range (25–100 Hz).^[2]

Research indicates that ambient noise from boats is doubling with each decade,^[45] reducing the range at which whale sounds can be heard. Prior to the introduction large-scale shipping, whale sounds may have traveled from one side of an ocean to the other.^[45] Environmentalists fear that such boat activity is putting undue stress on the animals as well as making it difficult to find a mate.^[45]

In the past decade, many effective automated methods, such as signal processing, data mining, and machine learning techniques have been developed to detect and classify whale vocalizations.^[47][48]

History

Whaling Captain Wm. H. Kelly was the first person known to recognize whale singing for what it was, while on the brig Eliza in the Sea of Japan in 1881.^[49][50]

After

William E. Schevill's study of whales also at one point harked back to the U.S. Naval operations that first set him down this path. As noted upon his death by the Society for the Bibliography of Natural History, "Bill helped defuse a tense moment between the USA and Soviet Union during the Cold War. The US military suspected that low frequency blips were being used by the Soviets to locate American submarines, whereas Bill showed these were produced by fin whales (Balaenoptera physalus) hunting prey."^[53]

Media

A humpback whale song

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Common humpback whale vocalizations on a windy day

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Orca calls and echolocation

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Call of an orca

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Orca echolocation

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A fin whale song

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A blue whale song

Recorded in the Atlantic (1)

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A blue whale song

Recorded in the Atlantic (2)

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A blue whale song

Recorded in North Eastern Pacific

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A blue whale song

Recorded in the South Pacific

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A blue whale song

Recorded in the West Pacific

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An Atlantic minke whale

None

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Atlantic minke whale pulse train

Recorded off South West Ireland April 2022

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Selected discography

• Songs of the Humpback Whale (SWR 118) was originally released in 1970 by CRM Records from recordings made by Roger Payne, Frank Watlington, and others. The LP was later re-released by Capitol Records, published in a flexible format in the National Geographic Society magazine, Volume 155, Number 1, in January 1979, re-released by Living Music/Windham Hill/BMG Records on CD in 1992, and remastered on CD by BGO-Beat Goes On in 2001.
• Deep Voices: The Second Whale Record (Capitol/EMI Records 0777 7 11598 1 0) was released on LP in 1977 from additional recordings made by Roger Payne, and re-released on CD in 1995 by Living Music/Windham Hill/BMG Records. It includes recordings of humpbacks, blues, and rights.
• Northern Whales (MGE 19) was released by Music Gallery Editions from recordings made by Pierre Ouellet, John Ford, and others affiliated with Interspecies Music and Communication Research. It includes recordings of belugas, narwhals, orca, and bearded seals.
• Sounds of the Earth: Humpback Whales (Oreade Music) was released on CD in 1999.
• Rapture of the Deep: Humpback Whale Singing (Compass Recordings) was released on CD in 2001.
• Songlines: Songs of the East Australian Humpback whales. was released in 2009.

See also

• 52-hertz whale
• Bioacoustics
• Biomusic
• Underwater acoustics
• Vocal learning

References

General references

• Lone whale's song remains a mystery, New Scientist, issue number 2477, 11 December 2004
• Frazer, L.N. & Mercado. E. III. (2000). "A sonar model for humpback whale song". IEEE Journal of Oceanic Engineering. 25 (1): 160–182.
  S2CID 44297027
  .
• Helweg, D.A., Frankel, A.S., Mobley Jr, J.R. and Herman, L.M., "Humpback whale song: our current understanding," in Marine Mammal Sensory Systems, J. A. Thomas, R. A. Kastelein, and A. Y. Supin, Eds. New York: Plenum, 1992, pp. 459–483.
• In search of impulse sound sources in odontocetes by Ted Cranford in Hearing by whales and dolphins (W. Lu, A. Popper and R. Fays eds.). Springer-Verlag (2000).
• Progressive changes in the songs of humpback whales (Megaptera novaeangliae): a detailed analysis of two seasons in Hawaii by K.B.Payne, P. Tyack and R.S. Payne in Communication and behavior of whales. Westview Press (1983)

• Tom Mustill: How to speak whale. A voyage into the future of animal communication, William Collins, 2022.
  ISBN 9780008363383
• "Unweaving the song of whales". BBC News. 28 February 2005.

External links

Wikimedia Commons has media related to Audio files of Balaenopteridae.

• Voices in the Sea has whale and dolphin sounds and interpretive videos
• Cornell University's Bioacoustics Research Program
• Right Whale Listening Network, a project of the above bioacoustics program at Cornell
• Whale Songs at the Avant Garde Project has FLAC files made from high-quality LP transcriptions.
• Perspectives in Ocean Science Listening to Whales, John Hildebrand, Scripps Institution of Oceanography
• The British Library Sound Archive contains over 150,000 recordings of animal sounds and natural atmospheres from around the world.
• Songlines: Songs of the East Australian Humpback whales.
• Recording of the bearded seal's "spiralling trill," one of the most phenomenal vocalizations of the underwater kingdom
• Watkins Marine Mammal Sound Database, Woods Hole Oceanographic Institution and New Bedford Whaling Museum