The Rhythms Of Elephant Seals

DON GONYEA, HOST:

Imagine you're an elephant seal on the prowl for a harem of mates. You blurt out this sound.

(SOUNDBITE OF ELEPHANT SEAL CALL)

GONYEA: But the guy just down the beach sends this retort.

(SOUNDBITE OF ELEPHANT SEAL CALL)

GONYEA: Turns out the sounds and rhythms of individual elephant seals are unique. And once the alpha male's signature call is heard, even if it's recorded and played back over loudspeakers, other males will scatter. Colleen Reichmuth is a research scientist at the Long Marine Laboratory. She joins us from the studios of KZSC at the University of California, Santa Cruz. Welcome.

COLLEEN REICHMUTH: Hi.

GONYEA: So first, just so people can get the proper image in their heads, describe what an elephant seal looks like?

REICHMUTH: Well elephant seals are sort of the titans of the animal kingdom. They're these huge, fat (laughter) animals. They can weigh up to two tons. Their most notable feature is a big, floppy nose or a proboscis that hangs over the front of their face, which is how they get their name.

GONYEA: So you've been studying these animals for 20 years. Tell us what's new here in this research on the sounds that they make.

REICHMUTH: Over time, we've learned to recognize individual males by their voices. We've learned that they can control one another on the beach using their voices alone. We actually were able to identify the acoustic features that support that recognition system. And we had suspected that the most important clues lied in the rhythm of the calls. And through a series of acoustical analyses and playback studies, we were able to confirm that that is the case.

GONYEA: So it's not just that it's a threatening sound that scares other males away. It's that they know exactly who it is?

REICHMUTH: Yeah. It's a very special signal that really conveys who's who. Many animal signals convey things like size or strength or even an animal's emotional state. But this particular signal is really used to convey identity, whether an animal is in a fight or whether he's alone, whether he's a high-ranking or a low-ranking male. That call is very stable throughout his life. It's like a fingerprint.

GONYEA: Are female elephant seals as vocal? And how would you compare them?

REICHMUTH: Well female elephant seals make very different sounds. The animals themselves are much smaller. So, as you would expect, their calls are a little more high-pitched.

(SOUNDBITE OF ELEPHANT SEAL CALL)

REICHMUTH: The calls of females kind of tell you what that animal is about to do. And, oftentimes, that is they are about to chase you away from their young pups. So they don't produce acoustic displays like the males do.

(SOUNDBITE OF ELEPHANT SEAL CALL)

REICHMUTH: They produce threat calls, and they produce pup attraction calls. And they seem to ignore the calls of these big males on the beach.

GONYEA: Let's listen to another sample. And I'm going to ask you to talk about it.

(SOUNDBITE OF ELEPHANT SEAL CALL)

GONYEA: There's a rhythm there for sure. Tell me what you're hearing in that.

REICHMUTH: I love that you picked out that call. That's actually the call of my favorite male over all these years.

GONYEA: OK.

REICHMUTH: It's the alpha male whose name was 1C. And he's what we call a multiyear alpha. He was able to hold the same harem on the beach year after year for several years, which is pretty rare in the system. So once he had a very distinctive call - kind of sounds like a galloping horse.

GONYEA: It's interesting because it doesn't sound particularly threatening, but I guess I'm not another male elephant seal.

REICHMUTH: In this case, the call doesn't need to be threatening. It just needs to be recognizable. And if you were really beat up by a guy who sounded like that, you'd remember that voice very well.

(SOUNDBITE OF ELEPHANT SEAL CALLS)

GONYEA: Well, it's been fun hearing your recordings. Colleen Reichmuth is a research scientist at the Long Marine Laboratory. She spoke to us from the studios of KZSC at the University of California, Santa Cruz. Thanks much.

REICHMUTH: Thank you so much, Don. Transcript provided by NPR, Copyright NPR.