Red-Eyed Treefrogs Rumble In The Jungle

They look cuddly, but red-eyed treefrogs have a secret dark side. When Michael Caldwell, Smithsonian postdoctoral fellow, filmed the frogs under infrared light he saw a curious behavior: they started shaking. Caldwell and colleagues decode the shakes in Current Biology.

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IRA FLATOW, host:

That music can only mean one thing: It's time for our Video Pick of the Week with Flora Lichtman. Hi, Flora.

FLORA LICHTMAN: Hi, Ira.

FLATOW: Our multimedia editor is here with another great video.

(Soundbite of laughter)

LICHTMAN: Thanks. It's I think it'll be a fan favorite, because it's an animal cam...

FLATOW: Always - already.

LICHTMAN: ...video. Yeah.

(Soundbite of laughter)

FLATOW: Don't have to know what animal it is.

LICHTMAN: Yeah, exactly. It's a this week is about the secret life of the red-eyed tree frog.

FLATOW: And how do you find these?

(Soundbite of laughter)

LICHTMAN: You know, the credit does not go to me, obviously. How does how do these scientists find these topics?

FLATOW: The secret life - say it one more time: the secret life of the red-eyed tree frog.

LICHTMAN: That's right. And you've probably seen a picture. Most people have probably seen a picture of one of these guys. They're the really bright green frogs. They've got blue on their sides and...

FLATOW: Yeah, yeah.

LICHTMAN: ...as the name suggests, those really beet-red eyes. And...

FLATOW: So they're not the rare things you never going to see. These are not (unintelligible).

LICHTMAN: I mean, they're like National Geographic's favorites, you know?

(Soundbite of laughter)

LICHTMAN: They're really pretty and really cute in the light of day.

FLATOW: But what's their secret?

LICHTMAN: That's right. So, Michael Caldwell went to Panama, and he had heard that these tree frogs have this mysterious behavior, where they shake. There is this old paper, 40 years ago, some scientists had written about this. And he studies them, and he had never seen this. So he's looking at them under all types of light. And then he finally decides to go out at night and use infrared video cameras. And suddenly, he discovers this whole other side of these tree frogs. And what happens is they're very territorial. So, one tree frog is on a bush, and it really wants its bush to be its bush.

FLATOW: Right. I'm not sharing this branch with anybody.

LICHTMAN: No, exactly.

FLATOW: Right.

LICHTMAN: And to fight over that, there's sort of this whole sequence where, first, they start out with the calls, these vocal calls.

FLATOW: Mm-hmm.

LICHTMAN: And then, it ramps up, this communication between these two male frogs. And they start rattling the branches.

FLATOW: By shaking their bodies. They shake...

LICHTMAN: They shake their bodies.

FLATOW: And we have a video. You have the video of them actually, in nighttime, the night-scope vision...

LICHTMAN: Yeah.

FLATOW: ...version of them shaking these branches. And you only can see them at night, on only - now on your video on our website at sciencefriday.com.

LICHTMAN: Yeah. And apparently, this is - it's not just the kind of aggressive. It's actually a really specific form of communication they found out, because they put little accelerometers - these are...

FLATOW: Right.

LICHTMAN: ...really sensitive microphones on the branches. And they found that every time that the frogs do this, no matter what frog it is or how big it is, it's shaking it at the same frequency, 12 hertz is the magic, you know, angry shake of the...

FLATOW: Twelve times of second...

LICHTMAN: That's right.

FLATOW: ...you have to shake it, or else it - you know.

LICHTMAN: Right. And then it signals that a wrestling match is about to begin, which you can also see in the video.

(Soundbite of laughter)

FLATOW: So if you want to see these frogs shaking the branches...

LICHTMAN: And wrestling.

FLATOW: ...and wrestling...

(Soundbite of laughter)

FLATOW: ...in the middle of the night and it's interesting, because their eyes sort of light up in that infrared light.

LICHTMAN: It's very creepy.

(Soundbite of laughter)

FLATOW: This is not a cute one. This is a creepy one.

LICHTMAN: It's a little bit scar. Yeah.

FLATOW: You can go to our website at sciencefriday.com and click on our Video Pick of the Week up there on the left side. You can also download it on our podcast and take it with you on our iPod podcast. So this is something different this week.

LICHTMAN: Yeah, it's different. And, you know, the thing that the researchers stressed was that we don't think about vibration as a...

FLATOW: Right.

LICHTMAN: ...form of communication, maybe because we're not that sensitive to it...

FLATOW: Right.

LICHTMAN: ...but, you know, they think that maybe this is sort of more meaningful than we've given it credit.

FLATOW: And thank you, Flora.

LICHTMAN: Thanks, Ira.

FLATOW: And if you want to see that form of vibration on our website, as I said, go to our website at sciencefriday.com, and you can watch this Video Pick of the Week.

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