Instant Genius - How whales may be using their haunting songs as a navigation system

Episode Date: November 7, 2025

Along with their vast size and habit of jumping playfully out of the water, whales are renowned for their haunting melodic vocalisations. However, after decades of research, scientists still aren’t sure why these mysterious creatures sing their other-worldly songs. Could it be a form of sexual display? Maybe it’s a method of communication? Or is it possible that the giant marine mammals are using these plaintive moans as a form of echolocation? Behavioural neuroscientist and author of the book Why Whales Sing Prof Eduardo Mercado certainly thinks so. In this episode, he tells us how whale songs can last for as long as 40 hours and be heard up to 1,000km away, how, acoustically speaking, whale songs have more in common with bat vocalisations than birdsongs and how ocean noise created by increases in fishing and shipping activity may be wreaking havoc on whales’ ability to navigate the ocean depths. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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So you can experience exceptional sound at home. Music just as the artist intended. Visit name audio.com to learn more. Hello and welcome to Instant Genius, a bite-sized masterclass in podcast form. Every Monday and Friday, you'll hear world-leading scientists and experts talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor at BBC Science Focus. Along with their vast size and habits of jumping playfully out of the water,

whales are renowned for their haunting melodic vocalizations. However, after decades of research, scientists still aren't sure why these mysterious creatures sing these otherworldly songs. Could it be a form of sexual display? Maybe it's a method of communication. Or is it possible that the giant marine mammals are using these plaintive moans as a form of echolocation? Behavioral neuroscientist and author of the book Why Whales Sing, Professor Eduardo Macardo

certainly thinks so. In this episode, he tells us how whale songs can last for as long as 40 hours and be heard up to 1,000 kilometers away, how, acoustically speaking, whale songs have more in common with bat vocalizations than bird songs, and how ocean noise created by increases in fishing and shipping activity may be wreaking havoc on whale's ability to navigate the ocean depths. So, welcome to the podcast. Thanks so much for joining us. Thank you. So today we're going to be talking about your book, Why Whales Sing?

So most people will know, at least vaguely, what whale song sounds like. But let's start with some sort of questions, general questions out of the way. First, do all whales sing? Not all wells have been recorded singing. Most of the larger wells, so in this context, Wells means baline wells, so the ones without teeth. And of those, all but two species have been recorded singing. It's not believe those two that haven't been recorded sing, but again, it's possible that they just haven't been recorded yet.

Yeah, so the sort of underlying theme or premise of the book is answering the question to why exactly whales do this. So the common answer is that it's some form of communication or a mating display. But you argue that there could be more to it than this. So can you break that down for us, sort of briefly at first, please? Yeah, so as you mentioned, for the last 50 years, it's been hypothesized that the whales are singing as a sort of sexual display to kind of show that they're worth mating with. And that hypothesis comes from bird song research, because it's been shown in many bird species

that that's how they're using songs. But there are some issues with that interpretation that led me to question whether that was the whole story. a lot of it relates to the way they produce sounds when they're singing, but also their behavior. In investigating those kind of factors, I was led to this possibility that they were using the sounds as a form of sonar rather than just to communicate with other wells. Yeah, so we can get into that in a bit more detail in a while. But let's have a look at the sort of physiology of whales. So how do they produce these sounds?

Because obviously you can't speak under water. Right. So it's all internalized with no air escaping from their head when they're making the sounds. And I'll focus on humpback wells because that's the main species that people have looked at acoustically and also in terms of the anatomy, although it's pretty similar across the baleen wells. So all of the large wells have what's called a laryngeal sac, which is basically just a big balloon within their body, such that when what's believed to happen, although it's never been observed,

is that when they expel air from their lungs, it goes through some vocal membranes that generate sound, and then the air goes into this sack, and then the sack returns there back into the lungs again for another round of sound production. They do seem to be vibrating membranes like other mammals, but the configuration that they have in their head does not match other mammals.

So they're doing something quite different, and they seem to have a lot of control that many mammals don't. So let's have a look at that from the other side, then. How do they perceive these songs? Again, because there's never been laboratory experiment with wells, it's not entirely clear. As a matter of fact, there wasn't even a direct measure of their hearing range until very recently. And when they did that with the Minky wells, which is one of the smaller Baleen wells, they discovered that they could actually hear

much higher than people assumed, higher than humans even, which is odd for a well that large. So they do seem to have an overlapping hearing range to what we have, but then what they do with the sounds they hear is almost entirely unknown. Yeah, so you mentioned there the kind of lack of of laboratory experiments. So how do we go about studying whale song? Well, all the studies so far have been field studies. Basically, you either observe what they're doing naturally and try to kind of just infer from observation what's happening, or you can generate sounds yourself and see how they respond to them, and that way get a sense about what they can hear and how they react to what they hear. Yeah, so as I said at the start,

a lot of people will be familiar with the kind of sound, it's sort of mournful sound, whale song has. But more scientifically speaking, what features does it have that, you know, that we can pick out? Right. So the song itself is interesting because when people were first listening to it, they didn't describe it as song. They just described it as well as making sounds or calling. And it was only after sort of detailed analysis with spectrographic tools, which allowed to see what the sounds look like over long periods, to be able to play back sounds at faster than normal speeds that people recognize that these patterns and the sounds that people kind of not really they may have noticed but not really realized what the structure was to them. And so the actual,

I guess, discovery of song wasn't discovery that they were making sounds, but that the sounds had these patterns that people hadn't really recognized before. So apparently thought to be males that do this more than females. Yeah. So all the, well, almost all the whales that have been sexed, I should say all the humpback wells that have been sexed singing have been males. Because of that, many researchers have claimed, especially recently, that only males sing. And it is true that when you go to the places where wells are studied the most, if you find a well singing, it's almost guaranteed to be a male. And so there definitely is a sexual bias in terms of which wells are singing.

But it's not entirely clear that that's always true, because they've only been really sex in a few places. And these songs, they're not like three-minute pop hits. They're going for quite a long time, don't they? Yeah, so when a single whale starts singing, how long it's going to keep doing that can vary quite a bit. But humpback whales have been recorded singing continuously without a break for up to 22 hours. Then Wells have been recorded singing continuously up to over 40 hours straight. So it's kind of mind-boggling. It's even possible they can do it.

So that would be called a song session, which is kind of a weird thing about songs is they're not discrete things that whales do. They're just kind of patterns that occur within this continuous stream of like incessant vocation. So do they tend to exhibit any specific behaviors when they aren't, you know, singing? Right. So most of the wells that sing haven't been observed very closely while they're singing because they're kind of out in the ocean and people are hearing them but not necessarily seeing what they're doing. Humpback wells have then observed the most. And most humpback whales that are singing are, first of all, alone. Second of all, they're not moving. And they're a fixed depth in a fixed position. So they're kind of like hovering in space for hours, producing these sounds.

like in our own little recording studio kind of without anybody coming near them for the most part except for when there's a lot of whales around and not really they do swim when they're singing but usually in a slow kind of like very I don't know strolly kind of manner and the songs can sort of propagate through the ocean for incredibly long distances yeah so for I mean humpback wells their songs are easily going five to ten kilometers just normally continuously you can sometimes record them over 100 kilometers away. Blue wells, when they're singing, can go 1,000 kilometers. So it's amazing how far these things travel in the ocean. And do they have any sort of common characteristics, or do they vary individually from whale to whale?

So across species, each species has its own kind of characteristic songs that it produces. Blue and Fenwell songs are much simpler than, say, a bowhead or humpback. If you go to focus on humpbacks, you can always recognize a humpback song. even though they're not always the same because they have some characteristic rhythmic features and some characteristic sounds within them. If you record a bunch of wells in a particular location, say around Australia or Hawaii, the wells in that region will all be producing very similar songs in terms of the kinds of patterns that occur. But even a single well within a single session is varying what it does in terms of the acoustics of the song, which is kind of unique among most mammals.

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which we mentioned earlier on. And that's this idea that it might be a form of sonar. So what do we mean by that, you know? Why have we come to this conclusion? Right. So it actually took a, I mean, it's not something that intuitively people had been thinking about in the context of larger wells,

but for cetaceans, that's the wells dolphins porpoises, it's been known for quite a while that many dolphin species, eclate, if not all. And so the idea that a cetacean would use sound as a form of perception is not a particularly new idea. Most people have not thought that baleen whales are using eclocation at all, mainly because they don't produce the same kinds of sounds that dolphins do, and they don't seem to catch fish in the same way that dolphins do. The reason why I started thinking about what was happening was specifically because of the way the wells were modifying the sounds they produced over time, adjusting frequencies and durations.

It's not something you see birds doing when they sing. They have very precise songs with very stable characteristics that would allow the birds to compare each other. But the wells were constantly changing their sounds with incessions across days and across years and ways that would make it very difficult for any wells to compare them because it's not the same thing each time. And so it was confusing to me why that would be happening. And so I started looking around seeing like what other mammals are doing anything like this constant adjusting. And the only ones that I saw were bats. And so this sort of common out.

And then it was clear why bats were doing it. It's because they can get different information depending on what signals they put out. And then I started thinking about, well, could Wells be getting different information? It's a problem if you're trying to listen to a well and you don't know what. sounds it's going to make, but if you're the one making the sounds, then it's very clear what you should expect to come back. And so it's a very different situation. And so that was sort of the starting point. And then from there, I started looking to see, well, well, what would they be looking for? And then so when wells are in the breeding areas, which is where they're most often seen singing,

they're very spaced out. Anybody that's in the field knows that you can't just go to one area and be sure there's going to be a well there. And may not see one the whole day in some places. They're all moving around all the time. There's no stable territories or anything like that. that's usually the case in birds. And so just this issue of like, how do the males and females get together? Started to, they have to, they can only hear each other. That's the only choice, really. And so in that context, it's like, okay, well, there's two ways they can hear each other.

Either the females are making sounds that allow the male to know where they're at, or they're going towards the males so that they don't, males don't have to find them. But there was no evidence of either of those things happening. There weren't recordings of females making sounds or approaching males. So the only other possibility was that the whales knew where the females were at because it could perceive them directly. And so in exploring that option, that's when I started looking into the details of the acoustics and the physics of it and how far away a well could use a sound to detect another well. Yeah, so going back to the anatomy, we now know that whales have incredibly complicated brains that are related to their audio processing abilities. You know, what can we say about that?

Right. So actually, I know my background is in your, I'm a professor of neuroscience, so I'm very interested in sort of the neural aspects, but of course, you can't really study that directly in humpback wells, other than looking at anatomy, which is what basically people know about a baleen well brains is what their, their structures like. And even that's not well known. But when I started looking at what was known about the humpback well ear in particular, I just, I was kind of amazed to discover that the inner ear, this is the first level of processing, was extremely dense innervation. So compared to a human, humpback whales have like five times a number of neurons innervating their ear, which means that for every little millimeter

of tissue we have, they have like twice as many neurons, basically, monitoring what's coming in, which is not seen in birds. The only other animals that have that level of nervation are dolphins in Balukas. So if you just look at the front end of like what kind of resolution do they have, they have about as good as you can get in the animal kingdom. Yeah, so this is obviously a really complex behavior. And sometimes sort of evolutionary biologists will look for kind of intermediate species, intermediate examples of complex behaviors. If we've been able to find anything like that related to this. So if you're talking about complexity of the songs, that would mainly be the humpback wells and bowhead wells who are the most complex singers like i mentioned before blue and fin

wells songs are really quite simple fin wells are just producing one maybe one or two sounds over and over same for blue wells and so those i would say are the intermediaries where probably that's probably what the you know original form was some kind of very simple repetition of sounds giving some basic information in a very simple environment and then as well sort of like progressed then the complexity was added onto that, I'm guessing, although no one's going to ever know for sure, to deal with new problems that arose once the whale started expanding their range of activities. So let's talk a bit about conservation then, because historically, and still some country is legal in some countries, whaling was quite popular to get the oil for the lamps and things like this.

That's been stopped in most countries now. But what hasn't been stopped is, or what's grown up, during that period is fishing and shipping. And now these are huge vessels that presumably make an awful lot of noise. So what effect is this having on the whales? Right. So it's interesting historical like trajectory of the whalers kind of almost wiping out entire species of baleen wells for, you know, to make watches work better basically with oil or to make soap and shampoo be more available.

And then at some point, people said, like, do we really want to make these animals extinct to wash our hair with a certain kind of, you know, shampoo? And then that sort of active killing of whales, as you mentioned, was kind of stopped. And I think now the impression is that, well, we solve that problem because we're not actively harpooning them, or at least most people aren't. But I think now they're actually in more danger, possibly than they were when the whalers were going after them. because at least some of the wells could escape the whalers by, you know, moving around and being more cryptic. But in the case of shipping, the shipping lanes right now cover everywhere. So you can't really escape it.

And the sounds that are being introduced in the ocean are by these shipping, these large ships that can carry containers, you can go online and hear them. They're just, they're so loud you can't hear anything else in the ocean. And so I feel like that's a bigger danger in some way. because there's no way the whales can escape it. And they also are having to deal with like climate change related ships and prey and things. So they have a lot of pressures on them simultaneously. And if they're using the songs for Sonor, it's particularly bad because if they were just

using the songs like a peacock tail, which is what the mainstream view is, maybe the female could just get closer and it would all be fine. But if they're using this to actually tell the females are at and they're basically driving in a blizzard, then they may never find the females. and then it's going to be a seriously bad problem. Yeah, so having said that, have there been any studies on, say, changes in the Wales migratory patterns, for example? There are some, they're difficult. Actually, not that long ago, many of the wells that were going to Hawaii seemed to disappear for a short period.

And people were getting really nervous then. They did come back. So they did something different during that time period, but people don't know exactly what, because it's really difficult. You know, when whales migrate, they're migrating from, like, the poles to the equator. So it's really hard to keep track of them the whole time. And then go anywhere, basically.

They have a few constraints on their swimming patterns. So, yeah, you can hear them when they're there, and so you'll know where they end up at, but you can't always tell how they got there. Yeah, so having said that, sort of, I've got one final question. Let's have a look into the future then. So what are some of the headline items?

Because obviously, there's still an awful lot to be discovered about this behavior. what are some of the topics that you'd like to, you know, tackle in the next five, say, 10 years? Yeah. So, I mean, one of the good things is that we have a lot of technologies now that weren't available before in terms of like drones and tags and autonomous recorders on the bottom. So we can collect lots of data that weren't possible to collect. And I think the big challenge or a big challenge that people haven't really tackled yet is what's happening when there's many wells in the same area singing. So now you've got a whole chorus of wells overlapping. How are they dealing? with that. Independent of what you think they're doing, whether they're trying to, like, judge other singers' quality or tell what the singers are. They have to pull all these details out of this mess somehow with their brain, known as a clue, I think, how they're doing it at this

point, or even what they're doing. So a lot of the work that I've been focusing on recently is trying to tease apart individual wells that are singing near each other, near being like three or four kilometers. They can hear each other. And what do they do when they hear each other? Do they modify their songs in real time? The answer is yes. And how do they do that? And what are they listening for? When do they change? When do they decide to actually interact in a way other than just vocally? Things like that. The main goal of this book is to expand people's views about what a well's life is like. And I think the idea that they're kind of talking to each other and or performing like musicians is attractive and sort of intuitive. But maybe we're projecting ourselves onto them.

And my goal is to kind of present the possibility that what they're doing is laying out the equivalent of like an acoustic spiders web around them that they monitor and that they're literally doing something much more like what eagles do and you know kind of like monitoring large areas simultaneously to try to pick out very tiny targets. It's weird to think of whales as being a tiny target. But when they're five kilometers away, they're quite tiny acoustically. They're probably like a gnat is to a bat. And so it's a very different scenario when you're imagining them like monitoring all of these little dots potentially moving, you know, many miles away. And then they have to decide what to do because if they do detect something that's like five kilometers away to actually join that other animal requires projecting where it's going

to be like 10 minutes in the future because they're not just sitting still. So they've got to kind of like work out like when should I start swimming, what angle and how fast to be able to intercept this other guy. It's a pretty complex problem. And so I think thinking about it from that perspective, it's very different to imagine a singer by himself, like kind of scanning and then deciding what to do next versus just sitting there singing hoping somebody likes what he's singing. And so that's kind of my main, I guess, goal is to move more towards that way of thinking about what might be happening. Thank you for listening to this episode of Vincent Genius, brought to you from the team behind BBC Science Focus. That was Professor Eduardo McCardo.

To discover more about the topics we've just discussed, check out his book, Why Wales Sing. If you liked what you just heard, then please do consider subscribing to InsinGenius on your preferred podcast platform. If you'd like to see our guests and hosts in person, then please do also check out our YouTube channel at ScienceFocus. The current issue at BBC Science Facus magazine is out now. Pick up a copy wherever you buy your favourite magazines or download us on your app store of choice. You can also find us on Apple News or online at sciencefocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal.

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