Tagging 16 singing males off Maui, Syracuse University researchers found that song themes line up with specific stages of a dive, with the most variable themes sung at depth.

Male humpback whales are among the ocean’s great singers. In their breeding grounds, they produce long, complex songs made of repeating units that can be heard for kilometers underwater. All the males in a population sing roughly the same song, which gradually changes over a season. Why they sing, and how the songs are structured, has fascinated scientists since the 1970s.

A new study adds a surprising factor: the dive. Writing in Current Biology, researchers at Syracuse University report that the structure of a humpback’s song is closely tied to its dive cycle. The study is described as the first to link the full structure of humpback song to a complete dive.

Tags that listen and move

The work was led by Julia Zeh, who carried it out as a doctoral student in the Bioacoustics and Behavioral Ecology Lab of biology professor Susan Parks. From 2018 to 2024, the team tagged 16 singing male humpbacks off Maui.

The tags are suction-cup devices about the size of a tablet that record both sound and movement before detaching and floating to the surface for recovery. Researchers attached them from small boats using long poles and, more recently, using drones. Some of the tagged whales sang continuously for up to 16 hours.

Combining the sound recordings with the movement data let the researchers see exactly where in a dive each part of the song was sung.

Themes and depths

Humpback songs are organized hierarchically. Individual sounds, called units, combine into phrases, and repeated phrases form themes. A complete song cycles through several themes and can last 10 to 20 minutes before repeating.

Earlier research had noted that some themes tend to occur as whales approach the surface. The new study found a much more complete pattern: recurring themes lined up with specific parts of the dive.

Singing humpbacks often adopt a characteristic posture, hanging head-down in the water at a depth of roughly 15 to 25 meters while they sing. They surface periodically to breathe and then descend again. Scientists have long noticed that singers tend to surface at similar points in their songs, but the full relationship between song and dive had not been mapped.

The themes sung while a whale held a relatively steady depth at the deepest point of its dive varied more than other themes. The researchers suggest these variable themes may be shaped by sexual selection, potentially signaling a male’s individual quality to females or rivals.

“This gives us direction for which parts of the song to investigate if we’re interested in variation, which is likely driven by sexual selection,” Zeh said.

Other themes may be constrained by physiology and environment. A singing whale must manage its oxygen and buoyancy while producing sound, and those demands may limit how much certain parts of the song can change.

Humpbacks produce sound by moving air within their bodies rather than exhaling it, recycling air between their lungs and other air spaces. Because air compresses as a whale dives deeper, the physics of sound production changes with depth, which could influence what sounds a whale can make at different points in a dive.

Listening for disturbance

The findings could have practical uses. If song themes correspond to particular dive stages, researchers might eventually infer a whale’s depth or position from acoustic recordings alone. That could help establish baseline behavior and detect when whales are disturbed by vessel traffic or underwater noise, both growing concerns for marine mammals.

Passive acoustic monitoring, which uses underwater microphones to listen for animals, is already widely used to track whales without disturbing them. Zeh now applies that kind of work in her current role leading the Archival Passive Acoustic Monitoring Team at the Maine Department of Marine Resources, after a postdoctoral appointment at NOAA’s Northeast Fisheries Science Center.

“Projects like this one, where we combined acoustics with movement data, gave me the tools to ask exciting questions about whale behavior and the opportunity to be creative in how we look at well-studied phenomena like humpback whale song,” she said. “These experiences inform how I conduct research and have given me the foundation for my current work in ecological monitoring and conservation.”

Beyond Hawaii

It is not yet known whether the patterns hold for humpbacks elsewhere. Zeh expects similar physiological constraints to apply but notes that songs may evolve differently in different populations, including between the Northern and Southern hemispheres. Studies of other breeding grounds would help show how universal the link between diving and singing is.

The study used a modest number of animals, a reflection of how difficult it is to tag singing whales. But the long recordings from each animal provide an unusually detailed view of how song and movement interact.

“My time at Syracuse changed the way I think about what’s possible in this field,” Zeh said. The results suggest that to understand one of nature’s most complex animal songs, scientists need to follow the singer down into the deep.

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Notes

1. Study on humpback whale song structure and dive behavior. Current Biology, 2026. DOI: 10.1016/j.cub.2026.07.014.
2. Syracuse University. “How a whale’s dive shapes its song.” EurekAlert!, 3 August 2026. https://www.eurekalert.org/news-releases/1138432.

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