For male humpback whales, singing is serious business. Their haunting, complex songs can last for hours and travel for miles underwater, playing a central role in finding mates during the winter breeding season. But despite decades of research into what these songs sound like, scientists have had far less insight into what the whales are physically doing while they sing — until now.
A new study reveals a previously unknown link between the structure of a humpback whale's song and the whale's movement through the water. Researchers attached small suction-cup recording tags to 16 singing humpback whales off the coast of Maui between 2018 and 2024. The tags, about the size of a tablet, recorded both underwater sounds and movement before detaching and floating to the surface for retrieval.
The team, led by Julia Zeh, a doctoral graduate of Syracuse University, made several striking discoveries. Some whales repeated their songs continuously for up to 16 hours without stopping — an endurance feat that would exhaust most human performers. More importantly, recurring song elements called themes lined up consistently with specific portions of a whale's dive cycle. While earlier researchers had noticed that certain themes tended to appear near the surface, no one had previously connected an entire song structure to an entire dive cycle.
"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. Themes sung during the deepest part of a dive showed different variability than themes sung elsewhere, suggesting those sections may be more strongly shaped by mate attraction. In other words, the deepest parts of a whale's song might be where males work hardest to stand out from the competition.
Themes tied to other parts of the dive may be constrained by the physical demands of singing underwater — managing oxygen, buoyancy, and pressure while producing sound.
The findings also have practical applications. Acoustic monitoring is already a common tool for tracking whale populations, but understanding how song relates to movement could allow researchers to determine a whale's depth just from a recording. That could help scientists establish a clearer baseline for normal humpback behavior, an essential reference point for detecting when whales are disturbed by vessel traffic or ocean noise.
Whether the same patterns hold for humpback populations outside Hawaii remains an open question. Testing that would mean collecting comparable tag data from singing whales on breeding grounds around the world. For now, this study offers a new window into one of the animal kingdom's most elaborate acoustic performances.