22 minute read
Listening to Leviathans
Laura May-Collado plunges into the depths of a 50-year-old mystery: why do humpback whales sing?
Story and Photography by Joshua Brown
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Call me wishful. Some two miles off the Pacific coast of Costa Rica, in a fiberglass fishing boat, researcher Laura May-Collado scans the horizon. She’s hunting for humpback whales in this warm and watery part of the world. And I’m looking around too, tipsy on antisea-sickness medicine, hoping to see a white whale, perhaps breaching above the waves like the second coming of Moby Dick.
I do have reason for faint hope. While it’s true that only three white humpback whales have ever been reported in the real world, May-Collado told me a fourth was spotted last October—a baby one, perhaps an albino, the first ever seen in Costa Rica. And a few days ago, there were reports that the young whale had returned to these same coastal waters. “There’s a chance we might see it,” May-Collado told me. But so far this morning—no white humpback. In fact, we’ve seen no whales of any color or kind. Still, we’re only in the first half-hour of this scientific expedition and we have more than 200 ocean miles to travel over the next three days.
May-Collado is an evolutionary biologist at UVM, an expert on the acoustics of aquatic animals, a research associate at the Smithsonian Tropical Research Institute, and chair of a committee of scientific advisors to the Society of Marine Mammalogy. She doesn’t use a harpoon—her best hunting tools are her ears.
As the boat buzzes and roars over the surging sea, May-Collado opens a Pelican case, takes out a digital recorder, a hydrophone on a long cable, a blue speaker, and some other electronics— then she connects them all together and signals to Junior Monge, the captain, to stop. He cuts the engine and now the sounds are wind and splashing. Hand over hand, May-Collado lowers the hydrophone into the azure water and holds the speaker to the side of her head for several long minutes, like a giant Lego version of a cell phone. She’s listening for the famed songs of humpback whales—but she doesn’t hear any. “There are no males singing right now—maybe they're more towards Caño Island,” she says. “That’s surprising. It’s late August and we usually hear singing almost every hour of the day.”
To hear and record the whales (and dolphins too) is a primary reason May-Collado stands in the center of this boat, transformed from petite 52-year-old assistant professor into some kind of ocean-going superhero, her bookish spectacles hidden behind bug-like sunglasses, a purple facemask over her nose and ears to fend off the fierce sun, an all-black lycra Aqua Lung suit— and a baseball hat with UVM in pink letters.
“I have many questions,” she says. “One interest is to find out how important different areas in the ocean are for humpback whales.” She relies on sound for this work because it lets her probe into the darkness with the very same sense that these animals rely on for communication— plus it’s cheaper than chasing them with boats or airplanes (though drones are becoming a powerful new tool). “I can leave sensors underwater for months at time—listening for them singing—which gives me a better picture of when the males arrive, when they leave, and how many there are in a particular place.” Then she goes back to her UVM lab where she and her students run models to estimate the density of whales in the larger region. “That's very important because it tells us about changes in time and space and how whales use tropical habitat,” she says. “As the climate changes and the oceans get noisier, the whales change too.”
But underneath this applied conservation question runs a perhaps deeper one. “I just like to figure out how things work,” May-Collado says. “I'm fascinated about how these animals evolve such a complex repertoire of signals and songs.” Then she pauses, and says, more slowly, “And what are they there for?”
The short answer: “After 50 years of collecting data,” May-Collado says, “nobody knows why humpback whales sing.”
While the boat surges and drops over each wave, May-Collado’s longtime research partner, Jose Palacios-Alfaro—an independent Costa Rican scientist everyone calls Pala—stands tall on the prow, a living masthead, effortlessly balancing with his bare feet while holding a large camera. He points out Widow Rock, which means we’re at the border of Ballena Marine National Park, about 13,000 saltwater acres, a triangular wedge of strict protection in one the richest marine ecosystems in the world that stretches for hundreds of nearshore miles.
These waters provide haven for two populations of humpback whales that migrate here to mate, give birth, and nurse their young. One small and endangered group travels south from California beginning in December. But the whales seen at this time of year are a larger and more robust population that traveled north from Antarctica and Chile. They’re known by the romantic name Breeding Stock-G (BSG), one of 14 distinct global populations of humpbacks, a species found in every ocean basin in the world. These BSG whales spend the austral summer in the rich waters of the Antarctic Peninsula, filter-feeding thousands of pounds of tiny krill shrimp and fish each day, laying on tons of fat to make the 5,000-mile journey to Costa Rica, one of the longest mammal migrations in the world.
And, at 11:44 a.m., we spot a whale. Well, actually, I hear it before I see it, a faint hiss in the distance and then a thin black dorsal fin slicing between us and the shore. As the boat veers to follow it, the whale disappears under the surface, and we slow down and then stop near a large glassy patch of ocean it left behind. There’s a pregnant period of quiet scanning, rocking, waiting. Suddenly, a huge snorting spray and mass surfaces right next to our boat. “Look, look, look,” says MayCollado. It’s not one whale; it’s a mother and baby, rising like two arching serpents from the deep. Sibilant water rockets from the mom’s double blowholes, a beautiful compressive blast that reminds me of the most basic and miraculous fact about whales: they breathe air.
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Early the next morning, we collect oxygen tanks at a nearby scuba shop and then push the boat off the beach in a silver mist. We’re running southwest in a slice of sunshine between marshmallow clouds that pour over the forested mountains on shore and a row of rain clouds on the horizon. Yesterday, we spotted dolphins and several groups of humpbacks, including an aggressive male trying to get between a mother and her baby, perhaps a subdominant youngster with lusty dreams. He was soon sent packing. But May-Collado didn’t hear any males singing, so today the hunt continues, farther out to sea: we’re heading to Caño Island, a hotspot for humpbacks some nine miles offshore, but about 30 pitching miles from where we launched.
At 10:20 a.m., some dolphins cruise into view and we stop to look and listen. It’s a group of about 15 pantropical spotted dolphins, MayCollado says, one of three dolphin species we’ve seen. Pala and the other member of this team, Ana Lucía Rodriguez Tinoco, a professional underwater photographer, quickly don snorkel masks and fins to swim out to the dolphins, while May-Collado drops a hydrophone in the water to listen to their whistles and clicks— “and I can hear a humpback singing as well,” she says and hands me the speaker to listen.
As the crow flies—or, rather, as the frigatebird flies—Laura May-Collado was born about 30 miles from here in the tiny village of Palma Sur, where her father worked for banana companies. “I grew up in the middle of nowhere,” she says. “I was always on the boundary between forests and plantations, and every night it was a cacophony of sounds. I wanted to know: what animal is making that sound? My passion is sound.” Then, in college, she took a field biology course where a huge group of dolphins came close. “I could hear these amazing sounds from the boat—and I was hooked,” she says. “I had to figure out what was the role of sound in the life of these animals—dolphins, whales, manatees, fish; they all make so many sounds that we’re just beginning to understand.”
As I put the blue speaker to my ear, I begin to understand her passion: the dull roar of wind and engine gives ways to a phantasmagoric undersea-scape of rising squeals, cow-like grunts, longing squeaks, yowls, growls, and guttural groaning. It’s musical and discordant, familiar and utterly strange. It sounds like Chewbacca with a kazoo was given a part in 2001: A Space Odyssey. This is a song that only the male humpback whale can sing.
And song seems to be the right way of describing this noise—not language. Perhaps there will be the uncovering of precise, descriptive communications in humpback songs, but probably not. Like a choir, the male humpback whales in any breeding area learn to sing together. Whatever it’s for, it’s intensely social. “The males will first arrive and they begin to sing slightly different songs, but then by mid-season they merge into the same song—and then everybody's singing the same song,” May-Collado says.
Herman Melville believed that whales could neither smell nor speak. “The whale has no voice,” he wrote in 1851. But, in 1967, marine biologist Roger Payne discovered that humpbacks actually have a great deal to say. The release of his haunting recordings, as an LP record in 1970, electrified people around the world by showing that the whale’s underwater world was alive with many voices, "exuberant, uninterrupted rivers of sound," Payne wrote. Songs of the Humpback Whale remains the best-selling nature sound record of all time and helped usher in radical changes in how many people viewed whales—from ferocious, mindless undersea monsters to gentle and wise undersea giants.
A complex scientific perspective on humpback whales lies somewhere other than either of these views—but the change came just in time. The 19th-century’s wooden whale boats and, later, steamers armed with rocket-powered harpoons and bombs killed tens of thousands of whales—far beyond what could be sustained. This history of slaughter was compounded by the diesel-powered, whale-hunting factory ships that set out after the Second World War and peaked their harvests in the 1960s. In 1973, humpback whales were listed under the Endangered Species Act. By this time, many whale species were profoundly depleted and several critically imperiled. In 1986, the International Whaling Commission finally imposed a moratorium on whaling around the world, which has allowed many populations to survive and some to recover—including the humpbacks that now pass by our boat.
Last night, I was a bit deflated when MayCollado told me that we would see no white whale—she had gotten a text that it had been spotted off Peru, much too far for us to have any hope of it showing here at Caño Island. But my daydream of the mystical wonder of the white whale—an inversion, perhaps, of Ahab’s nightmares—has been given a useful drubbing by seeing normal whales in the flesh.
At 10:43 a.m., a whale surfaces so close that its 30-ton mass makes the boat feel puny. A curving ridge of gouged blue-black skin, sheeting with water—a momentary sculptural waterfall, frothing at the bottom. I hold my breath as it rises, its dorsal fin adorned with several large barnacles. The back edge of the fin shows raw and red, and, along its flank, round white scars from barnacles now scraped off. I later learn that the parallel grooves and many long furrows across a whale’s skin may come from the sharp barnacles as males push against each other in a competitive scrum, seeking top position with ovulating females; or when mothers try to defend their calves from killer whales looking for lunch; or, if they’re lucky, from ships that strike but don’t kill them. It’s no musical picnic out here. Maybe the whales sing to calm their nerves.
“But we don't know yet, despite all these years of research,” May-Collado says, “we don't know yet the purpose of the song itself. Is it primarily to attract females or is it primarily to discourage physical competition? We don't know that.” There have been a few studies where scientists play recordings of humpback whale songs and females don’t necessarily come closer—but males do. Other studies show that males tend to sing more when there are more females around. “It’s possible that the song has at least two functions,” May-Collado says. Perhaps males use singing to size up their competition: a larger humpback’s song emits at a lower frequency. “Oh, you’re bigger, better stay away,” says May-Collado. And females might be able to listen to singing to evaluate a male or several males at the same time—without having to set eyes on the guys.
A humpback whale can see and smell and has an exquisite sense of touch; a humpback can even detect the pee of other whales in the water. But its most developed sense is hearing. You can see it in a whale’s brain and body: their auditory centers are extensive and their ears and sound-producing organs are highly specialized for underwater communication. Toothed whales, like sperm whales, use high-pitched pulses of sound as sonar to navigate and hunt, while baleen whales, especially humpbacks, are fantastically perceptive of low-frequency noises. “Sound is more convenient because they can do it at depth, they can do it where it's dark and still maintain contact with one another and coordinate activities. They can separate relatively long distances and still hear each other,” May-Collado says. In fact, the lowest pitches of humpback song travel thousands of miles, allowing them to communicate with each other across an entire ocean basin.
Which helps explain why their songs remain a mystery. Mostly humpback singing is heard in breeding areas, but sometimes they sing in feeding areas too, or while migrating. “We need to see how whales are arranged in a space when they're singing to be able to say how the song connects to behaviors,” MayCollado says, “to see females move and respond to the male songs.” But a whale is a huge animal with a huge underwater movement pattern—and sonic connections that may be miles apart but intimately close. “It's not like with birds where you can tag them, and you know where their territories are, and you can see where the males are singing, and how the others respond, and when the female arrives,” says May-Collado. “With these guys, you can't—not even with a drone.”
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The next day, our last out on the ocean, Caño Island again blinks into view, a low gray cigar against a darker gray storm cloud. The rain seems to be sweeping away from us to the northeast, and, as we draw closer, the sun begins to catch the tropical trees, rocky outcrops, empty beaches—and one low hut under the palms (the ranger station, it turns out). Having moved on from Moby Dick, I’m trying not to think about Robinson Crusoe or, a worse cultural blunder, Gilligan’s Island.
Next year, in this marine protected area and other places off Costa Rica and Panama, MayCollado hopes that she and her students will be able to attach acoustic recording tags to a number of whales—with suction cups—to see what she can learn from hearing and tracking whales at the same time.
Plus, this new tag technology will allow her to deepen her investigations into female humpback sounds, some of the first ever conducted. “For a very long time, we thought that females just didn't produce sound,” MayCollado says. “Usually when you are with a female and a calf and you use a hydrophone, you don't hear anything.” But the mothers have reason to speak quietly with their calves, trying not to draw attention from males who might harm the youngsters, or from killer whales who would happily eat a humpback calf. The attached tags will allow her to hear their subtle sounds.
“We've ignored how females communicate,” May-Collado tells me. “Males take all the central stage because they have these beautiful songs, while females are very quiet. They don't sing, but they do produce other sounds to communicate. Do they use them with just their babies? Or maybe they use them when there are other females around? We don’t know.”
After Junior’s delicious lunch of fresh tuna salad and even fresher coconut—he hacks them open with a machete while still driving the boat (he’s a lifelong fisherman, turned tourist-boat operator, turned scientific navigator with exceptional whale-spout scouting skills)—the team turns to scuba diving. Pala deployed one sound trap near this island nine months ago—where it samples and records frequently, giving a long-term record of a soundscape changing through the seasons. Now it’s time to bring it up from the bottom.
Pala and Ana Lucía Tinoco hoist heavy tanks onto their backs, secure masks and oxygen regulators to their faces, take a backward flop from the boat’s edge—and disappear under the opaque silver surface. A few minutes later, May-Collado and I follow them with masks and snorkels. The transformation from above the water to below is stunning; it’s like the air world was painted by a sober decorator taken with flat gray—and the underwater world was built by Playmobil. A riot of purple and yellow fish swirls between towering columns of pink coral; a six-foot shark tools slowly along a glittering canyon; and a stream of luminous bubbles comes up from where the divers are collecting the trap. Maybe the whales sing for the wonder of being a mammal under the sea.
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On a sultry Friday afternoon in September, on the second floor of Marsh Life Science, Franny Oppenheimer and Megan O’Connor—both UVM class of 2024 and in an accelerated master’s program—as well as fourth-year Ph.D. student Maia Austin, sit at silent computers watching sounds scroll across the screen. Oppenheimer explains that what I’m looking at is a spectrogram. “It’s basically a picture of sound,” she tells me, pointing at a double panel of orange and yellow lines spiking upward. “This is how we visualize the whale songs.”
Last year, Oppenheimer took a research course with Professor May-Collado where students learned to analyze selections from the more than three million minutes of marine animal sounds May-Collado has collected from around the world—contributing directly to her burgeoning research program. This fall, the next cohort of undergraduates in this course will begin to analyze the sounds and songs collected in the long-term sound traps and short-term sound recorders May-Collado brought home to Vermont from Costa Rica a few weeks ago.
Though, really, what home means to May-Collado is complicated. “I’ve lived in the U.S. for nearly 20 years, and raised my kids here, but I’m still an outsider,” she says. Being a Costa Rican woman scientist who speaks English as a second language, came to UVM as a post-doctoral researcher, had two children, eventually landed a lecturer position—and then made the rare leap from lecturer to a tenure-track appointment in the Department of Biology in middle age has been profoundly challenging. She says she’s had many great advocates and mentors along this path—including UVM Associate Professor of Biology Sara Helms Cahan—which may explain why Oppenheimer and the other students in the lab are quick to say she’s got their back. “We were first-year students and she made us uncross our arms and power pose,” recalls O’Connor. “She’s very big on female empowerment,” says Oppenheimer.
In 1971, Roger Payne made a case that the male humpback’s sounds should be called songs because of their repetitive, music-like structure: the whales make short sounds, which he called “units,” that, like the letters in the alphabet, can be combined into longer repeated phrases. And the phrases nest into themes—and each song, some as long as a half-hour, is composed of a set of repeated themes. The humpbacks from Antarctica that we watched have a song with a modest four themes—not as sparse as the two-themed song of the California whales, but not as ornate as other populations in the world that can have eight or more themes. And the songs themselves, like a Grateful Dead concert, can be sung, over and over again, for many hours in a “song set.”
May-Collado and her students spend a lot of time identifying, cataloging, and analyzing these pieces of humpback song. And, more recently, applying machine learning and artificial intelligence techniques to this task. Oppenheimer is aiming to build a “kind of dictionary,” she says, of humpback whale noise, looking at the smallest units—that mysterious alphabet. “There are about 35,” she says, pointing at a small set of nearly horizontal lines on the screen. The “whale lab,” as the students call this place, has contributed to an important discovery that’s been made over the last half-century: these songs evolve. “One of the key things that we've been learning is that whales are learning. Learning new songs from each other and then passing them along, horizontally,” May-Collado says. Males may drop or add a unit, chop out a phrase or even add an entirely new theme. Then other males in their group will do the same, converging on one song, but changed from the year before. Their song—their communication—is being changed by culture. Usually this is a gradual morphing of the melody over years, allowing geographically separated populations of humpbacks to develop dramatically different songs.
But, like wandering minstrels, sometimes males will move into another group and bring a new unit or theme—or even an entirely new song.
May-Collado has been recording humpbacks in Costa Rica since 2016 and shared some of her recordings with her colleague Renata SousaLima in Brazil. “And they noticed that one of the themes that was very popular in 2018 in Brazil was now in Costa Rican whales. How did it make it here—from the Atlantic to the Pacific?” May-Collado asks. “We don't know yet! Is it possible that a whale from Brazil went to Antarctica to feed and then decided, ‘Oh, I'm going to go around and check out this other region,’ and brought this new element, and our whales added that theme to the song?” And sometimes evolution becomes revolution. In 1996, a marine biologist in Australia noticed that a male on the east coast was singing the west coast song. Two years later, all the east coast males had ditched their song and had taken up the new melody. And research published last year shows that humpbacks transmit their songs from Australia to French Polynesia and on to the Pacific coast of Ecuador. New whale music may go right around the globe this way, creating, the scientists write, “vocal culture rivalled in its extent only by our own.”
May-Collado wonders if the same kind of cultural transmission could happen at Caño Island—except between north and south. “We love Costa Rica because it's a place where northern and southern hemisphere whales use the same habitat but at slightly different times of the year,” she says. “But over time, we have noticed that there's more and more potential for overlap between the two populations.” Which is why her team has set song recorders along that path. While we were in Costa Rica, Franny Oppenheimer was doing the same thing, as a summer field job, dropping hydrophones into waters off Panama. “We’re looking to see if we actually find that acoustic overlap and if that also translates into gene flow,” May-Collado says. “This would be, perhaps, the only place in the world where two hemisphere humpback populations exchange genes and songs.”
It's a general principle of biology that innovation is important. And that’s true in animal communication. “The more novel or complex your song is—the more attractive it becomes. That’s been shown in birds,” May-Collado says. “It could be that whales are evolving new songs that are going to be successful and attractive to females.”
As children, we’re all fascinated by nature, May-Collado believes, “dinosaurs or flowers or bats or snakes. And that goes away later when you grow up and have to pay your bills,” she says. “At some point, we all had a very deep connection. What will waken us?” she wonders. Perhaps a song will, even if we don’t yet know what it means. “It can remind you that you're connected to the natural world,” May-Collado says. “You're not living in isolation.”
