TRIPOLI — Stacey Snyder watched the sun set over her northern Iowa hometown one evening last month.
Observing an American flag blowing gently across the street, she estimated the power of the wind on a three-point scale: “I would say it may not be a ‘three,’ because it’s not totally extended, but it’s getting there.”
The conditions need to be just right — not too cold, windy or bright — for frogs and toads to feel comfortable serenading their potential mates. It’s why Snyder was sitting on her front porch May 5, prepared to make her yearly voyage to listen for the creatures who call nearby wetlands home.
In donating their listening skills to a state-run science project, volunteers like Snyder are helping ensure Iowa’s frogs and toads keep singing within a landscape that has lost an estimated 95% of its original wetlands.
“I know globally, decreasing populations are a challenge. So for us, as Iowans, this is a good baseline for us to refer back to,” said Snyder, an elementary school teacher who has been volunteering to count local amphibians for more than a decade.
It wasn’t until the 1980s that scientists turned their attention toward alarming declines in amphibian populations across the world. Concern within the broader conservation world trickled into Iowa, and in 1991 the annual statewide Frog and Toad Call Survey began.
The Iowa Department of Natural Resources relies on volunteers to keep it running. The information they collect about when different frogs and toads breed each summer, and where, serves as a yearly check that they haven’t succumbed to threats like climate change, disease or habitat loss.
“To have a dataset that stretches back that long is super rare and extremely valuable to really understand, ‘What the heck is actually going on?'” said Danny Hughes, a herpetologist at Coe College in Cedar Rapids. “Basically, sorting out the noise from the true signal in the data is only possible with a dataset that goes back that long.”
Finding that signal is especially important because frogs and toads are considered “indicators” in an ecosystem — they will be among the first to notice if something has gone awry. One reason is because their skin is permeable; if there’s a pollutant in the water, it will easily leech into their bodies.
Still, Hughes said that, conservation-wise, reptiles and amphibians tend to get less attention than cuddly mammals. And research funding is often tied to that attention.
“So (it’s important) to be able to say, ‘Hey, there’s only a few herpetologists here, how can we expand this and cast a wider net to bring in more potential observers?'” Hughes noted.
Iowa’s annual survey is funded through the sale of DNR license plates. In the 2021 fiscal year, they made up about 1.1% of the more than 2 million plates sold in Iowa.
Stephanie Shepherd, who has been overseeing the survey for the DNR since 2006, said there’s value in such long-term data — but there’s also messiness. The agency is in the midst of analyzing all of the data collected since 1991.
“I think a lot of the lessons we may be learning from this in-depth analysis are, ‘What are some things that we do need to be paying attention to?'” she said.
Shepherd said ideas that have surfaced so far include investigating how Iowa’s frogs and toads have responded to changes in land use and precipitation. A manuscript of the data analysis will hopefully be submitted by the end of this year.
Volunteers dedicate time, patience to listening for Iowa’s 17 frogs and toads
It’s up to the volunteers to keep things running in the meantime.
By 8:15 pm, Snyder was ready to begin with a prediction that she would hear at least three different species calling.
“But you never know,” she said. “They’re wild animals, right?”
Training a band of prospective volunteers in March, Shepherd listed off potential sounds they could hear walking around the Iowa woods at night.
Among them: a “long, rubbery snore with occasional chuckles.”
At least, that’s if there’s a northern leopard frog around. If there’s a bullfrog in the midst, the sound will more resemble a “pulsating foghorn.” The cricket frog sounds like two marbles banging together.
The call of the pickle frog, to the right listener, sounds “like a kid playing with an airplane, and making airplane noises,” Shepherd told volunteers.
“These are the males putting out there that they’re there; announcing to any frog lady that happens to be nearby that they’re available, they’re robust, they can make a really loud noise and sustain (it) for a long time,” Shepherd explained.
She also pointed out — to the volunteers’ apparent relief — that survey participation does not require the ability to recognize all 17 of Iowa’s frogs and toads by their mating calls. Most people only hear the few species that live in their corner of the state.
Instead, she told them the most important skills are time and patience.
That’s because the commitment entails traveling to wetland areas at night — when the sun is less threatening for wet-skinned creatures — three times throughout the summer. All in all, volunteering takes about 10 hours.
Some years it can be hard to find volunteers, she said. But many are devotees who have made it a summer habit.
Those people who come back yearly take part in challenges that are unique to Iowa’s landscape. Among them is a quest for the crawfish frog, which hasn’t been seen in the state since the 1950s.
“I usually tell them that I’ll buy them a cake, or throw them a parade or something if they actually find one,” Shepherd said.
In 2021 — the 30-year anniversary — volunteers collected data at an all-time high of 106 different “survey routes” and 716 wetlands.
For Snyder, the data collection has become relatively simple. If she comes across an unknown call, she makes a recording, then plays it back at home before logging the data.
“The one thing that I just try to go through in my mind is to make sure I truly know what I’m marking before I mark it,” Snyder said. “I don’t want to be wrong, because that skews the data.”
She easily identified the sound of the thumbnail-sized chorus frog, the most common in Iowa, on her first survey route of the season. She recorded a two out of three on the data sheet for “abundance” — meaning she could hear several frog calls, with some overlap, but surely not a full “chorus.”
“By the time you get to three, it’s like, ‘Woah!’ Your ears are blown,” Snyder said. “It’s really fun to hear that.”
That’s all she heard, though, at the slice of public land near the Wapsipinicon River.
About 97% of Iowa’s land is private. In the mostly remote area that evening, all she had to watch out for was the occasional sound of an airboat, canceling out the frog songs.
‘Just their presence is important’: Iowa’s picture might be bright, but researchers need data to say so
When the World Congress of Herpetology first met in Canterbury, England, in 1989, the topic of population decline wasn’t on the agenda.
But the story goes that the scientists there began comparing notes — and noticing similar, disturbing trends.
“The big story from that first Congress was, ‘What’s happening to all these amphibian populations?” said Paul Bartelt, a researcher who studies amphibians at Waldorf University in Forest City. “Some of them were disappearing from what seemed like pristine sites; they weren’t simply areas where you had widespread habitat destruction.”
Decades of research since has identified habitat loss, pesticide use, disease and climate change as factors causing population declines in amphibians. The deadly “chytrid” fungus, in particular, has contributed to declines in 500 species of amphibians and, as of 2019, 90 extinctions.
Bartelt got a bachelor’s degree in 1974 from Iowa State, and has spent his time recently studying restored wetlands in Winnebago County. He pointed out that all species of frog or toad won’t respond to threats in the ecosystem the same as the next. And it’s natural for their populations to fluctuate.
That’s why it’s important to gather data on the general size of frog and toad populations over time, and where they are located, he said. Exact numbers matter less.
“Just their presence is important,” Bartelt said. “Over time, the changes in abundance — if we can relate that to changes in weather, or changes in habitat, or with climate change, now, how might that be affecting them over time — it takes a number of years.”
Volunteers in the frog and toad survey are able to choose the route where they’ll gather data. Shepherd said it can be difficult to recruit people who will record data at sites that might not have as many calls to hear; it’s just not as exciting.
“But that data with zeroes — telling us frogs aren’t there, or they’re only there once every four years — is actually super valuable,” she said.
In the mid-1800s, the federal government gave states the power to drain wetlands and turn them into agricultural lands. In Iowa, by 1906, just a quarter of the state’s original 4 million acres of pothole wetlands remained; by 1970, it was less than 1%.
It “doesn’t take a rocket scientist” to figure out what will happen to an amphibian population if you take away its wetlands, Bartelt said. But he also wanted to know how long it takes them to find a wetland after it’s been brought back to life.
At least for the area he studies, the answer is positive for the amphibians: It might take several years, but with the right conditions, they will find it and start breeding.
The long-term analysis of the data is yet to be complete. But generally speaking, data show relative stability over time in Iowa’s frog and toad population, Shepherd said.
She shares the story of a newer volunteer, who emailed her this spring about his experience at a Jimmy John’s in Ames. With his newfound knowledge of frog calls, he identified chorus frog songs coming from a small patch of cattails nearby.
He wondered if it would be possible to create more spaces like it in urban areas.
“I think the take-home is that we need to be vigilant in monitoring these species, and keeping an eye on them and thinking about them, but at the same time, in Iowa, and in our state, it’s maybe not as bleak as we tend to think it is,” Shepherd said.
“We just need to give them as much help as we can to help them be resilient.”
Cleo Krejci covers education for the Iowa City Press-Citizen. You can reach her at [email protected]