Meet Austin’s chirping frogs. They are everywhere, but you never see them.

It’s the curse of radio reporters. When you hear something that’s mysterious, unexpected, or new, you want to get that sound. It doesn’t matter what time of day. It doesn’t matter what else you do. You want to capture it. What if you never hear it again? What if it is important? You gotta get it.

I’ve had this compulsion with a specific sound in my neighborhood for years. I hear it mainly, but not exclusively, in the spring and early summer. And strictly speaking it is not one sound.

Instead, it is a collection of sounds that seem to come from the same source. It’s kind of a high-pitched screeching, whistling, chirping sound. It comes from trees, rocks, walls and yards. Sometimes it even seems to come out of the ground. And it always seems to be the same animal making the sound.

It confused me because it sounded like it could be a lot of different things, and reviewing the dozens of recordings I made didn’t narrow it down.

I thought they were baby birds tweeting in their nests. It can sound almost exactly like this, except that a vibrating, crackling component comes in and destroys the impression.

That crunching sound is reminiscent of crickets or katydids, and for a while I decided it must be an insect.

But the sounds seem scattered and irregular. They do not follow the rhythm of insects. They also sound almost like a whistle sometimes, which I’ve never heard a cricket do.

I even briefly thought geckos were the cause. I had heard that geckos can make sounds and the sounds started roughly in the spring when I started noticing them in my garden.

But some theories pointed to a less organic origin. A neighbor of mine even thought the squeaking came from leaking or over-pressurized water pipes.

I have seen many things in my garden: insects, birds, snakes, lizards, toads, raccoons and water pipes.

I’ve never seen a frog before.

They turned out to be frogs.

People hear the frogs all the time, but never see them

On the UT Austin campus, there’s a place Tom Devitt calls “the frog room.” Aptly named, it contains shelves of terrariums, each housing a different species of frog.

Devitt is a professor and researcher at UT Austin specializing in amphibians. After emailing some experts about our neighborhood mystery, I was put in touch with him and he invited me to the frog room to reveal the likely source.

“A lot of people have never seen one, but you hear them all the time,” he said as he took down a terrarium that appeared to be filled mostly with a piece of limestone.

From that stone, Devitt teased a little frog. It was no more than an inch and a half long, tan in color with brown spots. It seemed very shy.

“This species is called a cliff-chirping frog,” he said. “It’s a native species.”

Devitt calls them cryptic. Small, good at hiding, hard to find.

He said this is the challenge of researching them: They are really difficult to observe in the wild. There are also several species of chirping frogs around Austin.

Cliffside frogs prefer rock outcroppings on the west side of town: i.e. the limestone. But Devitt suspects that what I heard in my yard could be the chirping frogs of Rio Grande.

It is a closely related species that probably makes its home in trees and vegetation. They are also more recent arrivals in Austin, possibly coming from South Texas with potted plants.

“There used to be a big farm in Brownsville, which is kind of where they come from,” he said. “We think they probably came from there, although we don’t know for sure.”

The Rio Grande Chirping Frogs have spread across much of Texas and Louisiana. Until now, they appear to have occupied a slightly different ecological niche than the Cliff frogs, offering little competition.

The frogs are everywhere, but we don’t know much about them

Chirping frogs aren’t like most frogs you’ve ever heard of.

First, they don’t need a lot of water. There is no tadpole stage for these frogs. They just lay eggs, and the young come right out as little baby frogs. This way they can live in gardens like mine, without a regular irrigation source.

Because they lay eggs, they also behave differently. While most frogs simply fertilize their eggs in water and leave them to fate. Chirping frogs stick around and take care of them.

In fact, the male frogs may actually be the primary caregivers.

‘They sit on the eggs, as it were. Move them,” Devitt said. “I think they generally just protect them from predators, that’s the idea.”

Somehow they survive the droughts and heat waves in Texas – probably by slowing down their metabolism. But exactly how it works, and how they know when to do it, is not entirely clear.

The more we talked, the clearer it became that there is still a lot we don’t know about these frogs. Even though they are everywhere.

“I just find it fascinating that we have biodiversity around us that we know almost nothing about,” Devitt said.

But he wants to know.

How exactly do they reproduce without water? How far do they travel in their lives? How long do they live?

“We have no idea,” he said.

It’s not even entirely clear why they make those strange noises.

“They call in two ways,” Devitt says. “One is a kind of little vibrating sound. The other is a kind of insect whistle or chirp.”

One sound is probably used to attract mates. The other to guard territory. But then again, Devitt has to study them to find out.

“I want to know everything about these frogs and what it’s like to be one,” he says. “That’s what it’s all about for me.”

To do that, you have to find them.

That’s how it is a few weeks later. KUT photographer Michael Minasi and I joined Devitt on a frog hunt at the Brackenridge Field Laboratory on Lake Austin Boulevard.

Join us on a frog hunt

The trail Devitt chose is perfect for hunting cliff frogs. It passes by what used to be a quarry, where blasts of stone exposed a limestone cliff face, creating a perfect habitat.

As I walked the path at night, my microphone picked up insects, birds and wildlife rustling through the undergrowth. But what we didn’t hear much about were the chirping frogs.

“As it gets later in the season, they come out less and less,” he warned.

Luckily he didn’t have to hear them to catch them.

One by one, Devitt saw the frogs, like shiny pennies on the rock in the light of our flashlights.

We found four that evening, despite their reluctance to squeak. Some were very small, maybe half an inch long.

“I wonder if these are the ones that came out this year,” he said.

He left the little ones alone. But he did collect one male to take to the laboratory.

He had hoped to see if the frogs would mate in captivity to learn more about how they reproduce and raise young.

But when I called to check in a few weeks later, he said he hadn’t had any luck and was returning them to the wild.

He thinks he may have waited too long into the year and collected frogs that were no longer interested in pairing.

One reason for that theory? Those super tiny frogs we found. If they just hatched, did this mean the end of the frogs’ mating season?

“I don’t want to speculate too much,” he said. “But… you don’t see little ones that often, and we saw a few pretty quickly.”

So in lieu of answers, we’ll end this story with another question about the mysterious chirping frogs of Central Texas.

Have we welcomed this year’s new generation of cliff chirps, fresh from a hidden clutch of eggs, into the world?

For now, there’s no way to know. But Devitt plans to look for answers next year when that strange beeping, whistling, chirping sound fills the air again.