Chapter 1: What is the main topic discussed in this episode?
Hey, it's Flora Lichtman, and you're listening to Science Friday. Investigating an iconic animal sound. The dolphin whistle. But what exactly is that dolphin saying? My next guest is trying to find out. She's an expert in dolphin communication and has been compiling a database of whistles from a pot of dolphins in Sarasota, Florida, that's been studied since the 1970s.
Chapter 2: What are dolphins actually saying with their iconic whistles?
And she's working to answer some fundamental questions about dolphin dialects. Dr. Leila Saig is a senior research specialist at Woods Hole Oceanographic Institution. Leila, thank you for being here.
You're welcome. Thank you for having me.
Let's do some Dolphin Whistle 101. So every dolphin has something called a signature whistle. Let's listen to some examples first. Okay, so what is a signature whistle?
Yeah, well, signature whistles are the closest thing to human names that we know of in the animal world. They really are a lot like our own names. So each dolphin has their own. They do make their own signature whistles a fair bit, which is sort of different than how we use our own names because we can usually see each other.
But they use them maybe when they're out, you know, sort of in places where they can't see each other and use them to keep in touch.
They're like, Flora here, something like that.
Yes, yes, that's right. That's right. Well, they'll kind of call out, I'm here, I'm here. But they do also copy each other and they will copy another dolphin's signature whistle as a way of calling out to them, which is more in line with how we use our names.
Do they name themselves? Like, how does a signature whistle come to be?
Oh, that's kind of the $60 million question or whatever. It was actually the focus of my PhD dissertation a long time ago. And I still cannot give you an answer. I wish I could. It's something I would love to know the answer to. We know they do learn their sounds. So they learn to produce their whistles.
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Chapter 3: What is a signature whistle and how does it function?
Usually at the very least, there's some subtle difference that we can use to differentiate one animal from another. Like it might end up going in an upsweep versus a down, something like that, even if the rest of it looks the same.
Although occasionally we do run into these very unusual situations like the calf that I was just mentioning that really developed a whistle that is so similar to his mom that we can't distinguish it. At least we can't. It's possible that there are some features that enable them to. But usually the distinctions are pretty visible to us.
Like we can see really big differences among the whistles for the most part.
And do they ID themselves the same way to their friends as they do to their families? Like do they have different signature whistles for themselves in different scenarios? We have not.
Seen evidence for that, although I wouldn't say that we have really looked specifically for that. They do vary aspects of their whistles in ways that make actually classifying their whistles a bit complicated. I guess other than one exception there, which I might just mention, we did look at the signature whistles of the adult females when they were communicating with their cats.
calves versus not with their calves, with other animals. And in that study, we did find that they tended to increase the maximum frequency of their whistles when they were communicating with their calves. And that was something that we likened to human motherese, which was, you know, when we speak with infants and small children and we speak in a more kind of sing-songy type high-pitched voice,
Like, ooh-doo-doo-doo-doo, you're so cute. Something like that. Yep, yep. So, I mean, we don't know if it's really functioning in a similar way in any way, shape, or form with dolphins. But it was pretty cool to find something, you know, that was similar in that way.
We have a recording that you took of a mother and her calf. Let's listen to it.
So those were slowed down.
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Chapter 4: How do dolphins learn and develop their signature whistles?
And we have been able to confirm that... In a bunch of ways. So, well, for one, the situation when dolphins are isolated, at least even temporarily or even just by a few feet from another dolphin or from, you know, from whoever they're with, that is a context that really promotes isolation. signature whistle production.
So they tend to just make a lot of signature whistles when they're in that situation of being isolated, even very briefly, and even still an earshot of other dolphins. And this was something that's been observed initially in captivity by the people who discovered signature whistles, David and Melba Caldwell, and they recorded isolated animals back then and found
that they made almost 100%, just one specific whistle. And then that's how they coined them, the signature whistles, because they were unique for each individual. And we do find in these health assessment contexts, not 100%, but we see maybe about 85% of any particular dolphin will typically be one specific whistle type. And so that's how we are able to call that the signature.
But then we also can confirm that by studying those same dolphins when they're just out swimming around doing their own thing. And we observe those same whistles. So we know that they're not just making some kind of, you know, different type of call when they're in that health assessment context, they are making their signatures.
I mean, graduating from 101, if I were taking intermediate dolphin whistle, are there other types of whistles that you've identified?
Yes, there are. So there's, as I already mentioned, signature whistle copies, which are pretty cool. And, you know, again, more like how we use our names. But then there are also a whole bunch of other types of whistles that we call non-signature whistles, which I wish had a different name because it's kind of a lame term.
kind of a lame name for them, but we'll be happy to take suggestions from people of other things we could call them. But for now, that's what they're called. And we have really only just started really studying these whistles in earnest. For many years, we kind of thought they were just sort of random.
We were pretty focused on the signature whistles and we would see these other whistles and be like, okay, those are, in fact, they used to be called variant whistles, which sort of implied that there was just something weird about them or whatever. And But we stopped calling them variant whistles. They're now just called non-signature whistles.
And we now know that there is not something weird about them. There's a lot of really cool things about them. They make a lot of shared non-signatures. So I've now discovered quite a few non-signature whistle types that we've seen made by multiple dolphins. Wow. And so we're trying to do some playback experiments now to understand how those non-signature whistles function.
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Chapter 5: Are signature whistles unique to each dolphin?
They're powerful animals. They could do harm if they wanted to. And, you know, I know a colleague of mine said, you know, would you jump on the back of a lion? I don't think so, you know. But people don't think of dolphins that way.
Once again, social media is misleading us. Mm hmm.
I think that's very true. And probably the TV show Flipper might have had something to do with it, too.
Dr. Leila Saig is a senior research specialist at Woods Hole Oceanographic Institution. Leila, thank you for being here with us.
You're very welcome. Thank you for having me.
This episode was produced by Shoshana Buxbaum. Before we go, Earth Day is coming up next week, and we want to hear about the places on our planet that you love and feel most connected to. Maybe it's the pond where you learn to swim, or your grandmother's vegetable garden, or that park where you do all your processing. Call us and tell us about your happy place. Take us there.
What does it look like? What does it smell like? What does it sound like? And why is it so important to you? 877-4SciFry is our number. That's 877-4SciFry. I'm Flora Lichtman. Thank you for listening.
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