Slo-Mo Cricket Chirps Reveal Secret Serenades
Want to know how crickets choose mates? Well, listen closely next time you're outside on a night when they're singing. Very closely.
It's the males that are doing that chirping; they're trying to attract females.
But it took biologist Laurel Symes of Dartmouth College years of listening — and recording — to figure out that different species of cricket have different calls. She slowed down the recordings and discovered that what sounds like a continuous call to us actually has pulses — or rhythm.
Take the snowy cricket, Oecanthus fultoni, also called the thermometer cricket because you can count the number of chirps in 13 seconds, add 40 and get the temperature in Fahrenheit.
"Within each chirp, there are eight separate pulses," says Symes. The pulses are arranged in a rhythm of two beats, followed by three beats, and then another three beats. "Dun-dun, dun-dun-dun, dun-dun-dun," as Symes does it.
Another kind of cricket, called Riley's tree cricket, divides its chirps into 11 beats. Presumably, a female can distinguish the calls of the males of her species from others.
Symes throws herself into her work — she collects crickets while she's on the road, keeping them in boxes in her car. "Motels have been ... well, usually they don't know. Sometimes you bring them in the back door, you ask for an exterior room. Campgrounds are good."
Why do this? "What I'm really doing is asking a female cricket, you know, what she likes, how the female choice acts on the male traits, and also what does and doesn't matter about the males' calls," she says.
Symes' recordings will be part of the collection of the Cornell Laboratory of Ornithology in Ithaca, N.Y.
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RENEE MONTAGNE, host:
And now in our series, Wild Sounds, we hear from the common cricket. Laurel Symes is a researcher from Dartmouth College, who records and even travels with crickets.
(Soundbite of crickets chirping)
Ms. LAUREL SYMES (Researcher, Dartmouth College): You know, I try and keep them in cardboard boxes. Like, I close up the boxes when I'm driving in the car. As you keep driving, you'll hear one start and then two start and pretty soon your whole car is full of chirping crickets. And then you hit a bump and they stop.
And so it's just, you know, Nathaniel Hawthorne said that two crickets are the sound of silence made audible. Well, he hasn't driven a couple of hundred miles with them.
(Soundbite of crickets chirping)
Ms. SYMES: They make this sound by rubbing their two front wings together. And so they have something that looks like a man's comb on one side and then just kind of a hard surface on the other side. And so they rub this thing across and it goes drink(ph), drink, drink.
But they do it so fast that all we hear is this continuous noise.
(Soundbite of crickets chirping)
Ms. SYMES: As far as we know, they really just call to attract females or to keep a little territory.
(Soundbite of a cricket chirping)
Ms. SYMES: That's called the Snowy Tree Cricket. It's also called the thermometer tree cricket, because you can actually count the number of chirps in 13 seconds, add 40, and you can get the temperature in Fahrenheit that way.
(Soundbite of a cricket chirping)
Ms. SYMES: When you slow that down even more, you know, it goes chirp, chirp, chirp. Within each chirp there are actually eight separate pulses.
(Soundbite of crickets chirping)
Ms. SYMES: So, it goes dun(ph), dun; dun, dun, dun; dun, dun, dun.
(Soundbite of crickets chirping)
Ms. SYMES: Dun, dun; dun, dun, dun; dun, dun, dun.
And if we were to speed that up to normal speed, what that would sound like is chirp, chirp…
(Soundbite of a cricket chirping)
Ms. SYMES: So, that's Oecanthus rileyi. And that's a western species. And when you slow those chirps down, each individual chirp is actually 11 separate pulses, so that you hear two-three-three-three.
(Soundbite of a cricket chirping)
Ms. SYMES: They're just these little tiny insects, but, you know, they have temperature dependence, and the physical acoustics of their wings and all these million years of evolution in this little tiny insect. I guess I've fallen in love.
(Soundbite of crickets chirping)
MONTAGNE: Our sounds come via the Cornell Laboratory of Ornithology. Thanks to NPR's Christopher Joyce for finding them. For more about chirping crickets, visit our Web site at NPR.org.
(Soundbite of crickets chirping)
(Soundbite of music)
MONTAGNE: This is NPR News. Transcript provided by NPR, Copyright National Public Radio.
