This is scientific American's 60 second science.

I'm Christopher Intagiyata.

For more than a hundred years, this sound has been missing from New Zealand's forests. It's like two stones being clicked together or two marbles being clicked together.

It's a very simple call.

Oliver Metcalf, a conservation biologist at Manchester Metropolitan University has studied the small bird that makes the noise, the he he he.

By the 1880s it was all but wiped out by rats and disease, which came along with colonists. But the he he did manage to survive. and

the he he did manage to survive on a predator-free barrier island

called Tehauturutoi.

And now they're being reintroduced to mainland New Zealand.

And they're going through the process of trying to restore the ecosystems they had prior to colonial settlement there.

So they're bringing back the birds one by one.

But the dense forests and the bird's unusual behavior

makes them tough to monitor.

They're very inquisitive.

They love people, so they'll come and see you.

If they hear you coming, they'll come and see you.

But that means that you have a problem with knowing what they would have been doing when you're not there.

So instead, Metcalf and his collaborators from the Zoological Society of London use that distinctive call to their advantage,

using an array of audio recorders to eavesdrop on 40

he-he-he-birds reintroduced to the North Island's Rotocarae Scenic Reserve. A month

later, analysis of the calls revealed that the birds had abandoned some areas of the reserve and settled into others,

suggesting they had begun to form territories, often close to water.

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