It’s the curse of radio reporters. If you hear something that’s mysterious, unexpected or new, you want to record that sound. It doesn’t matter what time of day. It doesn’t matter what else you’re doing. You want to capture it. What if you never hear it again? What if it’s important? You gotta get it.
I have had this compulsion with a specific sound in my neighborhood for years. I hear it mostly, but not exclusively, in the spring and early summer. And it is not, strictly speaking, one sound.
It is, instead, a collection of sounds that seem to be coming from the same source. It’s a kind of high pitched squeaking, peeping, whistling, chirping sound. It comes from trees, rocks, walls and yards. At times it even seems to come from the ground. And it always seems to be the same animal making the noise.
It confounded me because it sounded like it could be many different things, and reviewing the dozens of recordings I’ve made did not narrow it down.
I’ve thought it was baby birds tweeting in their nest. It can sound almost exactly like that, except there is a trilling, creaking component that comes in to destroy the impression.
That creaking sound brings to mind crickets or katydids, and for a while, I decided it must be a bug.
But the noises seem scattered and irregular. They don’t follow the rhythm of insects. They also, sometimes, almost sound like a whistle, which I’ve never heard a cricket do.
I even, briefly, entertained the idea that geckos were the cause. I had heard geckos can make noises and the sounds began in the spring roughly when I started noticing them in my yard.
But some theories pointed to less organic origins. One neighbor of mine even thought the squeaks came from leaky or over-pressurized water pipes.
I’ve seen many things in my yard: bugs, birds, snakes, lizards, toads, raccoons and water pipes.
I have never once seen a frog.
Turns out, it was frogs.
People hear the frogs all the time but never see them
On UT Austin campus there is a place that Tom Devitt calls “the frog room.” It is aptly named, containing shelves of terrariums each home to a different species of frog.
Devitt is a professor and researcher at UT Austin who specializes in amphibians. After I had emailed 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 while bringing down a terrarium which appeared to be mostly filled with a chunk of limestone.
From inside that stone, Devitt teased out a small frog. It was at most an inch and a half long, tan colored with brown spots. It seemed very shy.
“This species is called a cliff chirping frog,” he said. “They’re a native species.”
Devitt calls them cryptic. Small, good at hiding, hard to find.
He said that’s the challenge of researching them: They are really difficult to observe in the wild. There are also different species of chirping frogs around Austin.
Cliff chirping frogs favor rocky outcroppings on the city’s west side: thus the limestone. But, Devitt suspects that what I heard in my yard could be Rio Grande chirping frogs.
They are a closely related species that is more likely to make its home in trees and vegetation. They’re also more recent arrivals to Austin, possibly having come in from south Texas on potted plants.
“There used to be a big nursery in Brownsville which is kind of where they’re native to,” he said. “We think that’s probably where they came from, though we can't be sure.”
The Rio Grande Chirping frogs have spread across much of Texas and Louisiana. So far, they appear to have occupied a slightly different ecological niche than the Cliff frogs, and offered little competition.
The frogs are everywhere, but we don't know a lot about them
Chirping frogs are not like most frogs you’ve heard of.
For one, they don’t need much water. There’s no tadpole stage for these frogs. They just lay eggs, and the young hatch directly from them as little baby frogs. That’s how they can live in yards, like mine, with no regular source of irrigation.
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 care for them.
In fact, the male frogs may actually be the primary caregivers.
“They’ll kind of sit on on the eggs. Move them around,” Devitt said. “I think they’re typically just guarding them from predators is the idea.”
They somehow survive Texas’s droughts and heat waves — likely through slowing don’t their metabolism. But how exactly it works, and how they know when to do it, is not quite clear.
In fact, the more we talked, it became obvious there’s a lot we don’t know about these frogs. Even though they’re everywhere.
“I just think it’s 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 move in a lifetime? How long do they live?
“We have no idea,” he said.
In fact, it’s not even totally clear why they make those weird sounds.
“They make two types of calls,” said Devitt. “One is a kind of a little trilling noise. The other is a kind of insect whistle or chirp.”
One sound is probably used to attract mates. The other to guard territory. But again, Devitt needs 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 I’m about.”
To do that, you need to find them.
That is how several weeks later. KUT photographer Michael Minasi and I joined Devitt at the Brackenridge Field Laboratory off Lake Austin Boulevard on a frog hunt.
Come along on the frog hunt
The trail Devitt chose is perfectly suited to hunt cliff frogs. It runs along what used to be a quarry, where stone blasting exposed a limestone rock face, providing perfect habitat.
Walking down the trail at night my microphone picked up bugs, birds, wild animals rustling the underbrush. But one thing we did not hear much of was chirping frogs.
“As its gotten later in the season they’ve come out less and less,” he warned.
Fortunately, he didn’t need to hear them to catch them.
One after one, Devitt spotted the frogs, like shiny pennies on the rock in our flashlight beams.
We found four that night despite their reluctance to chirp. Some were very small, perhaps half an inch long.
“This makes me wonder if these are ones that hatched this year,” he said.
The small ones he let be. But he did collect one male to bring to the lab.
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 had had no luck and returned them to the wild.
He thinks he may have waited too long into the year, and collected frogs that were no longer interested in coupling up.
One reason for that theory? Those super tiny frogs we found. If they were freshly hatched, did they signal an end to the frogs mating season?
“I don't want to speculate too much,” he said. “But… it’s not all that often you see little ones, and we saw a couple of them pretty quickly.”
So, instead of answers, we finish this story with one more question about the mysterious chirping frogs of Central Texas.
Did we help welcome this year’s new generation of cliff chirpers, freshly hatched from some hidden clutch of eggs, into the world?
For now there’s no way of knowing. But Devitt plans to seek answers next year when that strange squeaking, whistling, chirping sound again fills the air.
