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Mar. 10, 2015 - Updated 04:16 UTC

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Japanese researcher works to combat crows by speaking their language

Oct. 23, 2017

Crows are often considered unwelcome, as they cause a disturbance with their cries and scatter trash across residential streets. Sometimes they even swoop down on unwary pedestrians.

So far, no one's managed to settle the turf war between human and bird, but now, one Japanese researcher thinks he might have found a way to peace talks by speaking their language.

The city of Yamagata in northern Japan is trying to limit the damage that crows inflict on crops, resulting in losses of about US$70,000 a year. A number of methods have been tried to keep crows away. One plan involved using hawks, but that wasn't a long-term fix.

The city finally turned to Naoki Tsukahara, a specialist in crow behavior. Tsukahara analyzed data to see how the sounds crows make relate to their actions. He believes crows have their own language of sorts, and says he has identified 40 "words" in their vocabulary.

"We study the crows' voiceprints, which are visual records of speech. Voiceprints of humans are used in criminal investigations," he says. "Here, crows make short, strong sounds to show they're on alert," he continues, as he plays a recording of a crow's cry. He plays other recordings which he says means "I've found food," and "It's safe here."

Tsukahara thinks he might be able to attract crows by communicating with them in their own language. "We will 'talk' to crows, and guide them from a place where we don't want them to somewhere they can stay," he says.

The experiment starts with a recording played from city hall. It uses the cry of a crow saying the place is dangerous, as well as that of another bird, a goshawk, which is the crow's natural enemy. Then, a speaker at a neighboring building plays a cry saying it's safe to be there. For the experiment, a courthouse and museum stand in for areas far from humans, where the crows should move to.

The sun sets, and crows begin to gather. The crows hear the recording and start to move. They settle near the courthouse and museum, just as predicted. The team successfully controlled the crows' behavior. "I'm happy it worked," says Tsukahara.

On the second day of the experiment, Tsukahara says "We'll use a drone that's fitted with a speaker that plays the sound of a crow fighting with a predator."

The drone will be flown near a group of crows, playing the sounds of a crow in a desperate fight and asking others for help. The team predicts the crows will mistake the drone for one of their own and follow it to rescue it from the predator.

The experiment begins. The unfamiliar flying object causes the crows to panic. It's playing a cry for help. But the crows don't approach. They start flying away, until they're all gone.

Crows in the area are of the species Corvus corone, often called carrion crows. But the sound used in the test was that of another species, Corvus macrorhynchos, or jungle crow. Tsukahara thought there would be no problem since he knows different types of crow can understand each other. "I think the crows flew away because they saw something strange approach, crying like a jungle crow. What I need to do is disguise the drone as a crow so I can guide them using various kinds of cries of different crow species," he says.

Part of the experiment failed, but it did shed light on the challenges that needed to be dealt with. Tsukahara and others will continue to use technology to help crows and humans live in harmony. He hopes to use artificial intelligence to communicate with the crows in real time.