TRIPOLI — Stacey Snyder watched the sun set over her northern Iowa hometown one evening last month.
Watching an American flag gently fluttering down the street, she rated the strength of the wind on a three-point scale: “I would say maybe it’s not a ‘three’ because it’s not fully extended , but it gets there.”
Conditions need to be ideal — not too cold, windy, or bright — for frogs and toads to feel comfortable serenading potential mates. That’s why Snyder sat on her porch on May 5, ready to make her annual trip to listen to the creatures that inhabit nearby wetlands.
By donating their listening skills to a state-run science project, volunteers like Snyder are helping to ensure Iowa’s frogs and toads continue to sing in a landscape that has lost about 95% of its original wetlands.
“I know that globally, declining populations are a challenge. So for us as Iowans, this is a good benchmark to refer to,” said Snyder, an elementary school teacher. who has been volunteering to count local amphibians for over a year. decade.
It wasn’t until the 1980s that scientists turned their attention to alarming declines in amphibian populations around the world. Concern within the wider conservation world spread to Iowa, and in 1991 the annual statewide survey of frog and toad calls began.
The Iowa Department of Natural Resources relies on volunteers to keep it running. The information they collect on when different frogs and toads breed each summer, and where, is used to check each year that they have not succumbed to threats such as climate change, disease or loss of life. ‘habitat.
“Having a dataset that goes back this far is extremely rare and extremely valuable to really understand: ‘What is really going on?’ said Danny Hughes, a herpetologist at Coe College in Cedar Rapids. “Fundamentally, sorting out the noise from the true signal in the data is only possible with a dataset that goes back that long.”
Finding this signal is particularly important because frogs and toads are considered “indicators” in an ecosystem – they will be among the first to notice if something has gone wrong. One of the reasons is that their skin is permeable; if there is a pollutant in the water, it will easily seep into their body.
Still, Hughes said, from a conservation perspective, reptiles and amphibians tend to receive less attention than cuddly mammals. And research funding is often linked to this attention.
“So (it’s important) to be able to say, ‘Hey, there are only a few herpetologists here, how can we expand that and cast a wider net to attract more potential observers? “, Hughes noted.
Iowa’s annual survey is funded by the sale of DNR license plates. In fiscal year 2021, they made up about 1.1% of the more than 2 million plates sold in Iowa.
Stephanie Shepherd, who has overseen the investigation for the DNR since 2006, said this long-term data had value, but there was also mess. The agency is in the process of analyzing all the data collected since 1991.
“I think a lot of the lessons we can take from this in-depth analysis are, ‘What things do we need to pay attention to? ‘” she said.
Shepherd said ideas that have surfaced so far include studying how frogs and toads in Iowa have responded to changes in land use and rainfall. A manuscript of the data analysis will hopefully be submitted by the end of this year.
Volunteers dedicate time and patience to listen to Iowa’s 17 frogs and toads
It’s up to the volunteers to keep things running in the meantime.
At 8:15 p.m., Snyder was ready to board with the prediction that she would hear at least three different species calling.
“But you never know,” she said. “They are wild animals, aren’t they?
Forming a group of potential volunteers in March, Shepherd listed potential sounds they could hear walking through the Iowa woods at night.
Among them: a “long rubbery snore with occasional laughter.”
At least that’s if there’s a northern leopard frog around. If there is a bull frog in the middle, the sound will be more like a “pulsating fog horn”. The cricket frog looks like two marbles colliding.
The pickle frog’s call, to the right listener, sounds “like a kid playing with an airplane and making airplane noises,” Shepherd told the volunteers.
“It’s the males coming out that they’re there; announcing to any lady frog that’s nearby that they’re available, that they’re hardy, that they can make a really loud noise and sustain it for a long time. time,” Shepherd explained.
She also pointed out — to the volunteers’ apparent relief — that taking part in the survey does not require the ability to recognize the 17 Iowa frogs and toads by their mating calls. Most people only hear the few species that live in their part of the state.
Instead, she told them that the most important skills are time and patience.
That’s because the pledge involves traveling to wetlands at night – when the sun is less of a threat to moist-skinned creatures – three times throughout the summer. In total, volunteering takes about 10 hours.
Some years it can be difficult to find volunteers, she says. But many are enthusiasts who have made it a summer habit.
Returnees each year participate in challenges unique to the Iowa landscape. Among them is a quest for the crayfish frog, which hasn’t been seen in the state since the 1950s.
“I usually tell them I’ll buy them a cake, or put them on a parade or something if they find one,” Shepherd said.
In 2021 – the 30th anniversary – volunteers collected data at a record high from 106 different “survey routes” and 716 wetlands.
For Snyder, data collection has become relatively simple. If she gets an unknown call, she makes a recording, then plays it back home before saving the data.
“The only thing I’m trying to get across in my mind is to make sure I really know what I’m scoring before I score it,” Snyder said. “I don’t want to be wrong, because it 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 registered a two out of three on the spec sheet for “abundance” – meaning she could hear several frog calls, with some overlap, but definitely 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, however, on the slice of public land near the Wapsipinicon River.
About 97% of Iowa’s land is privately owned. In the farthest region that evening, all she had to watch out for was the occasional sound of an airboat, canceling out the frogsong.
‘Just their presence matters’: Iowa’s picture may be bright, but researchers need data to tell
When the World Herpetological Congress first met in Canterbury, England in 1989, the subject of population decline was not on the agenda.
But the story goes that the scientists there started comparing notes — and notice similar and disturbing trends.
“The big story of 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 looked like virgin sites; they weren’t just areas where you had widespread habitat destruction.”
Decades of research since have identified habitat loss, pesticide use, disease and climate change as factors causing amphibian population declines. The deadly “chytrid” fungus, in particular, has contributed to the decline of 500 species of amphibians and, in 2019, 90 extinctions.
Bartelt received a bachelor’s degree in 1974 from Iowa State and recently spent his time studying restored wetlands in Winnebago County. He pointed out that not all frog or toad species will respond to threats in the ecosystem in the same way as each other. And it is natural that their populations fluctuate.
That’s why it’s important to collect data on the general size of frog and toad populations over time, and where they are, he said. The exact numbers matter less.
“Just their presence is important,” Bartelt said. “Over time changes in abundance – if we can relate that to weather changes, or habitat changes, or climate change, now how could that affect them over time – it takes a number of years.”
Frog and toad survey volunteers can choose the route where they will collect data. Shepherd said it can be difficult to recruit people who will log data on sites that might not have as many appeals to hear; it’s just not as exciting.
“But this data with zeros – telling us that the frogs aren’t there, or that they’re only there once every four years – are actually extremely valuable,” she said.
In the mid-1800s, the federal government gave states the power to drain wetlands and turn them into farmland. In Iowa in 1906, only a quarter of the state’s original 4 million acres of pothole swamp remained; in 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 remove its wetlands, Bartelt said. But he also wanted to know how long it takes them to find a wetland once it’s been brought back to life.
At least for the area he studies, the answer is positive for amphibians: it may take several years, but with the right conditions, they will find it and start breeding.
The long-term analysis of the data is not yet complete. But generally speaking, the data shows relative stability over time in Iowa’s frog and toad population, Shepherd said.
She shares the story of a new volunteer, who emailed her this spring about his experience at a Jimmy John’s in Ames. With his new 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 this in urban areas.
“I think the takeaway is that we have to be vigilant in monitoring these species, watching them and thinking about them, but at the same time, in Iowa and in our state, it’s not maybe not as dark as we tend to think it is,” Shepherd said.
“We just need to give them as much help as possible to help them be resilient.”
Cleo Krejci covers education for the Iowa City Press-Citizen. You can reach her at [email protected]