Humpback Communication

By William Rossiter

The social vocalization repertoire of east Australian migrating humpback whales is a scientific exploration of whale sounds that actually discusses what whales might be communicating to each other; courageous stuff! The study, authored by Rebecca A. Dunlop, Michael J. Noad, Douglas H. Cato, and Dale Stokes, was first presented over a year ago at the Fourth Joint Meeting of the Acoustical Society of America and Acoustical Society of Japan, and finally published in the Journal of the Acoustical Society of America 122 (5) November 2007 (http://www.acoustics.org/press/152nd/dunlop.html).

Thousands of hours of recordings of humpbacks migrating by Queensland, Australia found 660 sounds from 61 separate groups. At least 34 of the sounds reoccurred between groups and 21 were similar to bits from songs.

This vocabulary will not satisfy the mystics but it blew away the scientists. Despite decades of words written about humpback songs, little has been said about the social sounds of humpbacks. Deep in the paper is the caveat that: "These (statistical analysis) parameters, believed to be important to human observers, may not necessarily be of importance to the whales." The media, naturally, could not be so restrained. One Reuters headline proclaimed that "Australian Scientists Decode Whale Sounds".

This distinguished but overdue research narrowly avoids becoming cute with their words chosen to describe the humpbacks' sounds. Clearly, describing sounds is an art, not a science: "Ther-wop" and "Wop" were "common but brief harmonic upsweeps" below 60 Hz. "Wop" seemed similar to the "simple moans" from humpbacks in southeast Alaska, while in Australia it was most common with mothers with calves, and may be a contact call. One particularly vocal mother-calf and escort repeated eight rhythmic "ascending cries", lower in frequency but otherwise similar to the acoustically choreographed calls of hunting parties of Alaskan humpbacks. "Snorts" and "grumbles" were also low frequency, while mid-frequency harmonic sounds included "sirens", "short moans", "horns" and "violins". Longer harmonic sounds included "groans", "ascending moans", "modulated moans" "cries" "modulated cries" "ascending cries", and "trumpet." High-frequency harmonic "shrieks" or "squeaks" were contextually linked with disagreements. Amplitude-modulated sounds included "growls" and "purrs". Males made "purrs" when courting females, so of course the media described them as "C'mon baby" calls. Broadband, "noisy" and complex sounds included probable underwater blows, described as "barks," "bellows," and "creaks," while repetitive sounds included "grunts," "croaks," "pulses" and "low yaps".

The big news was that social sounds and bits from songs seem to be interchangeable. The study suggested that all social sounds might have come from songs, or songs from the sounds. Because of conditions, only the most obvious behaviors could be linked with sounds, such as when single males joining groups switched from low-frequency sounds to higher frequency song-like harmonic sounds. Would this be like humming a few bars of a hit tune as you join a party?

This research will be read from many perspectives. Let's squeeze a few thoughts from this research and rummage on the edge of science, without getting mystical or mushy: does the suggestion that humpbacks might say something about themselves or their environment leave you thrilled or threatened? Why does something so expected need science to make it real?

Because science documents, and occasionally explains, reality, we now know that humpbacks and humans are not alone: give homage to Alex, the legendary gray parrot, or Koko, the signing gorilla who, as the researcher would go home at the end of their day, would plead: "please don't go; I'll cry", or the orcas with dialects and ceremony, or the many examples of culture among an increasing list of creatures. But it is all relatively new information; Just a generation ago people found solace in their thumbs, which allowed humans to be the only tool users. Turns out non-human tool users are everywhere, and in the last few years non-human self-awareness and even some suggestions of abstract thought also have been found hidden in plain sight. People needing the solace of superiority are having an increasingly tough time, and the trend is clear. The real question is where to look.

So someone finally looked for, and found, that humpbacks share widely understood labels for things or feelings, and they use these labels while singing rhymes. This news is millions of years old. The real news is that someone finally looked for something already there. Lots more to do: We still have to learn if the song is about the labels, and if some labels mean "me" and "you".

What an opportunity for young researchers, to accept the challenge to study a different humpback population in clear waters, where behaviors and sounds can be documented in unambiguous context. This is already being done, carefully, with several dolphin projects. Will they find the different meanings for sounds adopted by different populations, and explore the cultural implications?

If the future enlightens us with humpback gossip or sagas will there still be people who will want to kill them? What would humpbacks say of whaling? Would the whalers listen?

A young humpback whale summering in Antarctica.
Photo courtesy of Luciana Möller.