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Repelling Bats

 

BOISE, ID – You’ve probably seen a gecko change colors.  Or maybe a praying mantis that blends into its surroundings to escape a predator.  Then there’s a skunk that will spray you when you get too close.  Animals have all sorts of ways to tell predators to back off.  But how do we know what they’re “really” saying?  Or how they started saying it?  Samantha Wright reports those are two questions an Idaho researcher is asking about moths and bats.

Jesse Barber spends a lot of time listening to sounds most people will never hear.  Like this:

Sound of a bat catching a normal moth

This is the sound a bat makes when it hunts moths.

Jesse Barber “And the sound you’ll hear is the echolocation the bat is producing, but I’ve lowered the frequencies down into our hearing range, if this were occurring in nature, we wouldn’t be able to hear it.”

Barber studies sensory ecology as assistant professor at Boise State University.  He looks at how animals process sensory information and then make decisions.  Right now he’s studying hawkmoths, the biggest moth in the night sky.  They’re about the size of a hummingbird.  And they’re hunted by the largest of bats.  It usually happens like this: a bat flies up to a moth, grabs it, and eats it.

Jesse Barber “And that’s your typical attack behavior, but when one of these moths makes a sound back at these bats, they break off that typical attack behavior.”

Barber figured out hawkmoths use sound to deflect a bat attack.

Jesse Barber “In Ecuador a few years ago, I discovered that some of them do just that, and they do it with modified genitals, the parts the male uses to clasp onto the female during mating, he makes ultrasound with those parts.”

Only male hawkmoths can make this noise.

sound production by a hawkmoth

Scientists have already shown that other types of Moths defend themselves by making a sound.  Tiger moths tell bats they taste bad.  Or sometimes they jam the bats’ sonar.  But Barber isn’t sure what hawkmoths are saying.  So he’s going around the world to South America, Peru, Borneo, and Southeast Asia to find out.  He’ll do the same thing in his lab at Boise State.

Jesse Barber “So in a recording studio upstairs, this large flight room, we will pit the bats against the moths and answer these functional questions, what is the function of the sound.”

He’ll use high speed cameras to capture the battles, which last less than a second.  Then he’ll take this footage and slow it down.  It sounds something like this:

sound of a hawkmoth talking back to play back of a bat echolocation attack

Barber wants to know how the moth uses sound.  He also wants to know WHEN the moth started using sound.  Did the sound evolve first for mating or for defense?

Jesse Barber “It’s possible that they evolved these sounds first for sexual interactions and subsequently they were coopted for bat defense.  This would be the complete opposite of how we think these defensive sounds evolved in Tiger moths, the other group of moths that make sound back to bats.”

But this isn’t just about the sound made by moths.  Barber says it really about understanding evolution.

Jesse Barber “There’s no doubt that there’s all kinds of amazing interactions between bats and insects that have yet to be described, because it’s not unlike the deep ocean, the night sky, it’s this place where there are these amazing things going on that we don’t have the ability to see.”

There also another reason for his research.  Barber says animals are going extinct at such a rate, that time is running out.

Jesse Barber “We’re in a golden age of biology right now, where we still have enough intact ecosystems that we can answer these questions, but it’s likely that my kids and especially  my grandkids, won’t have this option.”

It will take four years and a 270-thousand dollar National Science Foundation grant to find out what the hawkmoth says, and when it started using the sound. Assistant Professor Jesse Barber heads to Borneo next month, to convince moths to reveal their secrets.  And he’ll pit bats against moths in his Boise lab in May.

 

Copyright 2012 BSPR

As Senior Producer of our live daily talk show Idaho Matters, I’m able to indulge my love of storytelling and share all kinds of information (I was probably a Town Crier in a past life). My career has allowed me to learn something new everyday and to share that knowledge with all my friends on the radio.

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