Between December and April, male humpback song becomes the dominant source of underwater sound in many parts of Hawaiʻi, according to the Hawaiian Islands Humpback Whale National Marine Sanctuary. Many males singing at once make a chorus that the sanctuary measures with recorders on the seafloor, to follow koholā (humpback whales) through the season. The Ocean Count data sheets have no column for song, because the count is a visual survey done from shore.
This page summarizes what NOAA and the sanctuary publish about humpback song and points to their recordings. We are an independent site, not the sanctuary or the count.
Who sings, and what a song is
Only adult males sing. Scientists sort humpback sounds into song and non-song calls, as NOAA’s sanctuaries office explains it. A song has structure: short repeating units called phrases are organized into larger themes, which NOAA compares to a poem. Singing sessions can last from five minutes to more than 24 hours, with the same song repeated over and over.
In a given breeding area the males all sing the same current version of the song, and in Hawaiʻi that song changes over the season and from year to year, according to a NOAA sanctuary photo caption. The sanctuary also notes that whale song can carry for several miles underwater, far enough for one recorder to pick up whales across a wide area.
What the song is for
The sanctuary’s research page calls the exact function of song “a matter of scientific debate.” Its summary of the evidence is that song is probably a display of competitive fitness aimed mainly at other males, and less likely an attempt by males to attract females. A 2021 NOAA sanctuaries story describes song more broadly, as a way for whales to communicate, locate each other and attract mates. Where the two differ, we follow the sanctuary’s research page.
To test whether song carries information about a male’s fitness, sanctuary researchers have worked with the University of Hawaiʻi at Hilo and the University of Alaska Fairbanks off Maui. Divers locate a singer, record it with a calibrated recorder and video camera, measure its distance with handheld sonar, estimate its size from the video and take a biopsy sample to measure hormone levels.
How researchers use the chorus
The sanctuary keeps bottom-moored acoustic recorders in the water through the breeding season, and software measures how much whale song each recording holds. Researchers use the amount of song to track the relative presence of whales: when they arrive, when numbers peak and when they leave, compared across sites and years. From 2018 through 2021, the NOAA and U.S. Navy SanctSound project recorded at five locations in the sanctuary and three in Papahānaumokuākea Marine National Monument.
Because only adult males sing, a recorder captures one part of the population and nothing directly from females or calves. Dr. Anke Kügler, who has worked on the sanctuary’s acoustic surveys, told NOAA that visual surveys link the acoustic data to what is happening in the population, so changes in song levels can be checked against changes in the number of whales people see. The Ocean Count and the Great Whale Count on Maui are two of those visual records.
Where to hear humpback song
NOAA has published Hawaiian recordings you can play in a browser. The sanctuary’s February 2021 story “Eavesdropping on Whales” has three clips from SanctSound recorders near Olowalu on Maui, Makapuʻu on Oʻahu and Penguin Bank off Molokaʻi. The sanctuary’s acoustic monitoring page has a single song phrase.
To hear it live, you have to put your ears underwater. Love Big Island’s whale-watching guide, published by the same company as this site, gives step-by-step instructions for listening while swimming or snorkeling, with the ocean conditions to wait for.
Federal regulation 50 CFR 216.19 makes it illegal to approach a humpback within 100 yards by any means within 200 nautical miles of the Hawaiian Islands, and the sanctuary’s list of those means includes a person in the water. Listen from where you are and never swim toward a whale. Ocean Count volunteers are told never to enter the water during a count at all. The full rule, and what to do if a whale comes toward you, is on our rules page.