Maybe you heard some “ribbits” in the evenings for the past few weeks – it’s frog calling season, a time for the amphibians to find their mates.
Frog calls are also used to track their population, which is an important indicator of environmental health. But due to disease, pollution, and loss of habitat, Indiana, and the rest of the world, has seen a declining frog population over the past few decades.
In Northern Indiana however, efforts have been made to restore some wetland habitat to its natural state.
WBOI’s Virginia Alvino learned more about a research project tracking frog populations, in order to see if the Eagle Marsh Wetland restoration project has been a success.
There are about 20 species of frogs in Indiana.
“Each species has a species specific call," says Emily Stulik - a recent IPFW master’s graduate, who's studied amphibians here at Eagle Marsh in Fort Wayne for the past two years, under the direction of her advisor Bruce Kingsbury. “The Spring Peeper has this high peeping sound," which you can hear loudly, even outside the wetland.
“The Chorus Frog call they say it sounds like you’re running your thumb across the edge of a fine toothed comb, so it has this kind of high pitched trill,” says Stulik.
As we hike, Stulik mentions one more species she didn’t hear at this site two years ago, but did hear last year. It’s one of a few frog species in Indiana of special concern - that’s just one step away from endangered.
“Well I’m hoping we’ll hear the Northern Leopard Frog. That has a really soft, kind of guttural groany call,” says Stulik.
We tromp through water about half way up our shins to get a better listen at the first wetland.
Stulik explains the purpose of the frogs' calls is that “the males are advertising to the females, they are saying come get me, they are using their calls to attract females. They have done studies that show that females will mate with the males that have the longest loudest calls.”
Eventually we get to solid ground, but as we get closer to the frogs, we’ve got to quiet down. Stulik says “the frogs are funny, when you get close they’ll hear you and they’ll stop calling. Predator avoidance.”
Stulik's project measured presence and absence of frogs, meaning she would come out and just listen - What species was she hearing? Where were they? She says “the objective was to use them as biological indicators to assess the success and the health of restoration. to kind of get the overall picture of wetland health.”
Sarabeth Klueh-Mundy explains - she's an herpetologist for the state’s Department of Natural Resources.
She says frogs and amphibians are important to monitor because they have semi permeable skin, making them good environmental indicators - the proverbial canary in the coal mine.
“And any kind of harmful chemicals that are in the environment are going to hit amphibians first. So if you see die-offs in amphibians then we know that the quality is pretty poor," says Klueh-Mundy.
And frog populations across the globe have been steadily declining. A lot of that, especially in the Midwest, is due to habitat loss. Klueh-Mundy says “we used to have a lot more wetlands in Indiana, but a lot of them have been drained and turned into agriculture, but we really lost, or could stand to lose a lot of our biodiversity if we don’t have our wetlands.”
So what grad student Emily Stulik was trying to do, was use frog populations to see if the wetland restoration effort at Eagle Marsh worked – it may be wet again, but did the frogs come back? Are they really colonizing, and breeding there?
"I think that’s great," says Klueh Mundy. "I think we need more of that kind of monitoring to show people that yes, our efforts are making a difference. And I think it’s good also to point out that these kind of things don’t happen over night.”
Klueh- Mundy says it could take 5, 10 years for more species to return, but with patience, restoration efforts can be a success.
Back at the marsh, Emily Stulik explains her findings for some of the species. She says "I’ve shown in my research that they’re occupying about seventy percent of the sites, and their population increased year to year from 2013 to 2014, so they’re doing really well.”
Which is promising, "but on the other side, the other species of special concern, the Blanchard Cricket Frog is still really rare.”
Emily Stulik’s final takeaway – Eagle Marsh is supporting a healthy, viable amphibian population, but we all need to keep considering the importance of small wetlands, which can be delicate. Eagle Marsh can’t bring back every missing native frog species – but for these scientists, it’s a good start.
How you can help bring back the frogs:
Sarabeth Klueh-Mundy, herpetologist for the Indiana Department of Natural Resources, says everyone should care about all frogs, not just the ones in the preserves.
She says they're also good to have around in the garden because they eat a lot of insect pests.
"People can make a difference in their own backyard by creating wetlands, or limiting or eliminating the amount of herbicides or pesticides they use in their backyard," says Klueh-Mundy.
You can also volunteer with Sarabeth as a citizen scientist in the statewide Indiana Amphibian Monitoring Program, and help gather data to assist scientists.