They aren’t necessarily looking for mates, study suggests.

Humpback whale songs are long and complex and can last for hours. Only sung by males, those living near each other will all sing the same song, which is different from the songs by other males from different groups.1

Marine biologists have long believed that these interesting sounds likely helped whales find mates. But they may also play other key roles like asserting dominance with other males.

A new study continues research proposing that singing humpback whales aren’t just trying to attract females, but they may be using echolocation to explore their environments.2

Eduardo Mercado III, a professor of psychology at the University at Buffalo College of Arts and Sciences, has been researching this sonar hypothesis.

“I was introduced to whale song research in the early 1990s as a graduate student, when I was asked to assist in developing a catalog of the sound types Hawaiian whales were using to construct songs,” Mercado tells Treehugger. “It was about a year into that project that I began suspecting that singers might be using their songs as a form of echolocation.”

In his latest study, Mercado analyzed the variations in humpback whale songs recorded off the coast of Hawaii. He found mechanisms within songs that might be similar to those in the eyes of land animals as they examine their surroundings.2

Reproduction may play a part, but Mercado says the purpose of the song isn’t necessarily to attract other whales, but to find them. The results were published in the journal Learning and Behavior.2

“My original intent to describe how individual whales vary their songs was motivated in part because the reproductive hypothesis suggests singers should be as elaborate as possible since doing anything less wouldn’t be attractive to potential mates,” says Mercado. “But I was struck by the variety within songs looking at the statistics. Things weren’t uniform.

“Looking at what other behaviors showed similar profiles, I found fixation duration [the length of time eyes rest on objects] was similar to what whales were doing.”

About Humpback Whale Songs

Humpback whale songs are only sung by males. They are long and complex and can last for hours. Males in the same population will all sing the same song. Gradually songs can change over the years.1

The songs are heard most often during the breeding season in winter but are also heard in the summer months.3 A song usually lasts for about 10 to 20 minutes, but it’s repeated over and over again, often lasting for hours at a time.1

“Humpback songs are rhythmic sequences of intense sounds that singers produce repetitively for multiple hours. There are lots of convergent signs that these sounds are being produced to generate echoes: ecological, neural, behavioral, and acoustic,” Mercado says.

“It is the convergence of all these different lines of evidence that I find most convincing. Songs do attract males, but I doubt this is the goal of singing because such approaches/encounters account for less than 1% of the time that singers spend singing.”

Mercado explains that humpback whales produce both narrowband and broadband sound sequences, and each of these different signals offer distinct advantages in echolocation. Singing a vowel would be singing in narrowband while clicking the tongue against the roof of the whale’s mouth is broadband, he says.4

“Neither of these distinctions is important in terms of the reproductive display hypothesis, because it makes no predictions about why a whale should use either one,” he says. “But for the sonar hypothesis, it is significant since the acoustic information returned to the sender from clicks is very different from the information obtained through vowels. Which is why dolphins use only clicks to echolocate and most bats use only vowel-like sounds.”

Similar to bats and dolphins, humpbacks might be altering their songs based on their situations.

“The fact that they’re changing their songs so much, even within individual sessions, suggests they have more control than previously assumed,” says Mercado. “It’s why we have to start hearing these songs from new perspectives if they’re to reveal features we otherwise never would have considered.”