Have you ever been so fortunate as to have heard the long and complex song of a humpback whale? Marine biologists have long thought that these hauntingly beautiful songs, which are only sung by male whales, function like mating calls. However, it turns out that the whales may break out into song for a number of reasons.
A research study has investigated whether humpback whales sing songs as a form of echolocation to explore their surroundings. “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, explains Eduardo Mercado III, a professor of psychology at the University at Buffalo College of Arts and Sciences. “It was about a year into that project that I began suspecting that singers might be using their songs as a form of echolocation.”
Mercado’s most recent study, which analyzes the variations in humpback whale songs recorded off the coast of Hawaii, found mechanisms within songs that may function similarly to the eyes of land animals when they’re exploring their environment.
Also, while Mercado agrees that whale songs do play a role in reproduction, instead of using the songs to attract potential mates, the whales sing to help locate them.
“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,” Mercado says. “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.”
More about humpback whale songs
Interestingly, their complex song arrangements can last for hours and are sung exclusively by male whales. Males who are part of the same population and live near each other all sing the same song, but the songs can gradually change over the years. Males from other communities sing their own tunes.
While songs are mostly heard during the breeding season, they can also be heard during other times of the year. Usually, one song lasts for around 10 to 20 minutes, but the whales sing it on loop, often for hours at a time.
“There are lots of convergent signs that these sounds are being produced to generate echoes: ecological, neural, behavioral, and acoustic,” Mercado adds. “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 one percent of the time that singers spend singing.”
Humpback whales are also capable of producing narrowband sound sequences (like how bats use vowel-like sounds to echolocate), and broadband sound sequences (like the clicks that dolphins make to obtain information about their surroundings). Humpback whales, like bats and dolphins, may also be changing their tunes 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,” Mercado states. “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.”