Sounds & Songs

Humpback whale songs are among the most complex and beautiful sounds produced by any animal. Only male humpbacks sing, and they do so primarily during the winter breeding season in warm tropical waters. These songs are structured compositions consisting of distinct units (individual sounds), phrases (repeated sequences of units), and themes (groups of phrases). A complete song typically contains 5 to 7 themes performed in a specific order and lasts 10 to 20 minutes, though whales may repeat the entire song continuously for hours. One of the most remarkable aspects of humpback whale songs is that they change over time. Within a breeding population, all males sing essentially the same version of the song at any given time. But the song gradually evolves throughout each breeding season, with small modifications accumulating until the song at the end of the season sounds quite different from the version at the beginning. By the following year, the song has changed even further, and no humpback population has ever been recorded returning to a previous year's version. Research has also revealed that song innovations can spread between populations. Studies in the South Pacific have documented cultural waves of song transmission, in which a new song type originating in one population of humpbacks gradually spreads eastward across the ocean, being adopted by neighboring populations over the course of several years. This cultural transmission of songs is one of the most striking examples of social learning in any non-human animal. The purpose of humpback whale songs remains a topic of scientific debate. The leading hypothesis is that singing functions as a mating display, with males singing to attract females or to establish dominance over rival males. However, researchers have noted that females are not always observed approaching singing males, and singing sometimes occurs outside of the breeding season, suggesting that the songs may serve additional social functions. Some scientists have proposed that songs may help maintain group cohesion or coordinate behavior among widely spaced individuals. Humpback whale songs can be heard over distances of at least 20 miles, and under favorable conditions, the low-frequency components may carry much farther. The songs are produced without any external release of air, using the larynx and associated structures in a mechanism that scientists are still working to fully understand.

Toothed whales, including sperm whales, killer whales, beluga whales, and dolphins, have evolved a sophisticated biological sonar system known as echolocation. This ability allows them to navigate, find prey, and perceive their environment in detail using sound rather than sight, an adaptation that is essential in the often dark and murky underwater world. Echolocation works by producing short, focused clicks that travel outward from the whale's head. When these clicks strike an object such as a fish, squid, or the ocean floor, they bounce back as echoes. The whale receives these echoes through specialized fat deposits in its lower jaw, which channel the sound to the inner ear and brain. By analyzing the timing, intensity, and frequency of the returning echoes, the whale can determine the distance, size, shape, density, and movement of objects in its environment with remarkable precision. Sperm whales produce the most powerful echolocation clicks in the animal kingdom, measured at up to 230 decibels, making them the loudest biological sounds ever recorded. These clicks are generated in the spermaceti organ, a massive structure in the whale's enormous head that can account for up to one-third of its total body length. The clicks are so powerful that they can stun or disorient prey at close range, and they can detect squid at distances of several hundred meters even in the complete darkness of the deep ocean at depths exceeding 1,000 meters. Beluga whales are particularly adept echolocators. They produce rapid trains of clicks using a specialized fatty structure on their forehead called the melon, which can be consciously reshaped to focus and direct the sound beam. This flexibility gives belugas exceptional control over their echolocation, allowing them to scan their environment in fine detail. Belugas use echolocation to navigate beneath Arctic sea ice, find breathing holes, and locate prey in turbid river waters where visibility is near zero. Killer whales also rely heavily on echolocation, though their use of it varies between populations. Fish-eating resident orcas use echolocation frequently to locate salmon, while mammal-hunting transient orcas tend to be much quieter, minimizing their clicks to avoid alerting their prey. This behavioral flexibility demonstrates how echolocation use is shaped not just by anatomy but also by ecology and learned cultural traditions.

Blue whales produce some of the most powerful and lowest-frequency sounds of any animal on Earth. Their calls can reach 188 decibels, louder than a jet engine at close range, and they vocalize at frequencies as low as 10 to 20 hertz, near or below the lower limit of human hearing. These infrasonic calls are ideally suited for long-distance communication in the ocean, where low-frequency sound waves travel far more efficiently than higher-pitched sounds. Under favorable ocean conditions, blue whale calls can potentially travel hundreds or even thousands of miles, allowing individual whales to communicate across vast stretches of ocean. This long-range acoustic capability is particularly important for blue whales because they tend to be widely dispersed across enormous areas of open ocean, making visual or close-range contact between individuals relatively infrequent. Blue whale vocalizations are typically simpler in structure than the elaborate songs of humpback whales. They consist of repeated, low-frequency pulses and moans that last 10 to 30 seconds each. However, these calls show regional variation, with blue whale populations in different ocean basins producing distinctly different call types. Researchers use these regional call signatures to identify and track blue whale populations acoustically, monitoring their movements and relative abundance using networks of underwater microphones called hydrophones. One intriguing finding from decades of acoustic monitoring is that the frequency of blue whale calls has been gradually declining worldwide. Since at least the 1960s, the pitch of blue whale vocalizations has dropped measurably across all populations studied. Scientists have proposed several hypotheses to explain this trend, including changes in ocean noise levels, shifts in population density as blue whale numbers recover from whaling, and even changes in body size. The exact cause remains an open question and an active area of research. Fin whales also produce extremely low-frequency sounds, including a characteristic 20-hertz pulse that is one of the most common biological sounds in the ocean. These pulses are repeated at regular intervals and can be detected by seismometers on the ocean floor, so powerful that they were initially mistaken for geological signals. Fin whale vocalizations are among the lowest-frequency sounds made by any animal and can carry for hundreds of miles in the deep sound channel of the ocean.

Beluga whales have earned the nickname canaries of the sea due to the remarkable variety and expressiveness of their vocalizations. Belugas produce an astonishing range of sounds, including clicks, whistles, chirps, squeals, bell-like tones, and even sounds that have been described as resembling human speech. Their vocal repertoire is among the most diverse of any cetacean species, reflecting their highly social nature and the importance of acoustic communication in their Arctic habitat. Beluga vocalizations serve multiple functions. Clicks are used primarily for echolocation, helping belugas navigate murky Arctic waters and locate prey beneath sea ice. Whistles and other tonal calls serve social functions, including maintaining contact between mothers and calves, coordinating group movements, and possibly expressing emotional states. Research has shown that individual belugas have signature contact calls that function much like names, allowing group members to identify and call to specific individuals. The beluga's ability to modulate the shape of its melon, the rounded fatty structure on its forehead, gives it unusual control over the directionality and character of the sounds it produces. By reshaping its melon, a beluga can focus sound in different directions, effectively pointing its echolocation beam to scan specific areas. This flexibility, combined with the beluga's unusually mobile lips and facial muscles, gives these whales an expressiveness that is rare among cetaceans. Narwhals, close relatives of belugas, are also highly vocal animals. They produce clicks for echolocation, as well as whistles, trills, and pulsed calls for social communication. Narwhals rely on echolocation to navigate beneath the heavy Arctic pack ice that covers their winter habitat, where they must find small cracks and leads in the ice to surface and breathe. Bowhead whales are another surprisingly vocal Arctic species. Researchers have recorded bowheads producing an extraordinary diversity of songs, with over 180 distinct song types documented in a single population over just a few years. Unlike humpback whale songs, which are shared across a population, bowhead songs appear to show much greater individual variation, with different whales sometimes singing entirely different songs simultaneously. This diversity suggests a level of acoustic creativity and individual expression that is rare in the animal kingdom. Pilot whales use a combination of clicks for echolocation and whistles for social communication. Each pilot whale pod has a distinctive repertoire of call types, essentially a group-specific dialect. These dialects help pod members recognize each other and maintain the strong social bonds that are a hallmark of pilot whale behavior.

The underwater acoustic environment that whales depend on is increasingly threatened by human-generated noise. Ocean noise pollution from commercial shipping, military sonar, seismic surveys for oil and gas exploration, and construction activities has increased dramatically over the past century, with ambient noise levels in some ocean areas doubling roughly every decade since the 1960s. This rising tide of anthropogenic noise poses serious challenges for whale communication. Many whale species rely on sound as their primary means of long-range communication, using calls and songs to find mates, maintain contact with group members, and navigate across vast ocean distances. When background noise levels increase, whales must either call louder, shift to different frequencies, or accept a reduced communication range, a phenomenon scientists call acoustic masking. Research on North Atlantic right whales has demonstrated that chronic exposure to shipping noise causes measurable stress responses, including elevated levels of stress hormones. During the days following the September 11, 2001, attacks, when shipping traffic in the western North Atlantic dropped significantly, researchers observed a corresponding decrease in stress hormone levels in right whales, providing compelling evidence of the physiological impact of ocean noise. Blue whales and fin whales are particularly affected by low-frequency noise from large commercial vessels, which overlaps directly with the frequency range of their calls. Studies have shown that blue whales call more loudly in areas with higher shipping noise, suggesting they are actively trying to compensate for the masking effect. However, this compensation likely comes at an energetic cost and may not fully restore their communication range. Military sonar, particularly mid-frequency active sonar used in naval exercises, has been linked to mass strandings and deaths of beaked whales and other deep-diving species. The intense sound pulses from sonar can cause whales to alter their diving behavior, surface too rapidly, or flee from important feeding or breeding areas. Several mass stranding events involving beaked whales have been directly correlated with nearby naval sonar exercises. Conservation measures to address ocean noise pollution include vessel speed reductions in critical whale habitats, rerouting shipping lanes to avoid important feeding and breeding areas, seasonal restrictions on seismic surveys, and the development of quieter ship designs. The International Maritime Organization has issued guidelines for reducing underwater noise from commercial shipping, though compliance remains voluntary. Protecting the acoustic environment is increasingly recognized as essential for the long-term survival of whale populations that depend on sound for nearly every aspect of their lives.