Wesselman Woods roads are closed at night to protect migrating amphibians. Here, volunteers cross on foot to find and count salamanders. (Tim Jagielo / WNIN News)
Staff with Evansville’s Wesselman Woods counts amphibians every March on warm rainy nights with citizen scientists. Annual count season is not only educational — can indicate quality of soil and water.
- Small-mouthed salamanders along with other species of amphibians, migrate up to 200 yards to temporary spring pools to breed. (Tim Jagielo/WNIN News)
Volunteers and staff are gathered in Wesselman Woods near the gate marked “Roads Closed for Amphibian Crossing.”
Rain is pattering off hoods and umbrellas as they don headlamps and check flashlights.
Derek Walsh, Wesselman Woods director of natural resources and research, begins briefing the group.
He said that salamanders hide out in the forest most the year until these exact conditions — above 50-degrees and moderate rain, and then they strike out to breed at vernal pools near the end of winter.
Vernal pools are temporary, existing due to snow melt and are devoid of egg-eating fish.
“So when these vernal pools fill up in the springtime, that's when the salamanders know it's time to go,” Walsh said. “So on warm, rainy nights like this, that's when they migrate en masse.”
They’ll be looking for salamander species Spotted, Small-mouthed, Marbled and Northern Slimy Salamander.
“One thing to note, we do not have the permit to touch the salamanders, so please do not touch the salamanders," he said. "However tempting.”
After a briefing on spotting and measuring salamanders, they take off in the dark, headlamps and flashlights sweeping the grass and park roadways.
Wesselman Woods is the largest urban old growth forest in the country and some salamanders travel 200 yards to breed at these springtime pools.
It didn’t take long before finding the first specimen in the grass — a Small-mouthed salamander.
That wiggling creature was spotted by Erin Bunkers, who appreciates such a scientific opportunity in Evansville.
“I just think it's really interesting,” she said. “I'm new to salamander hunting, and I found out about it a couple months ago.”
It was measured by eight-year old Lilly Vollman, at about 9 centimeters.
- Lilly Vollman, 8, completes her first salamander measurement. (Tim Jagielo/WNIN News)
Walsh said much is learned from counting these amphibians, because salamanders and other amphibians are very sensitive to pollution.
“They have permeable skin, and so by counting salamanders, we can make an inference about the health of the ecosystem,” Walsh said, adding that they’re known as an “indicator species.”
They can indicate how ecologically intact the ecosystem is. By counting the salamanders over the years, trends in the population can become apparent, along with the health of the ecosystem.
Last year it was too dry and they only counted 50 or so salamanders total. This season, the last two attempts were too cold.
But Tuesday’s count yielded 90 salamanders — mostly Spotted and Small-mouth species. They can assume that there were over probably 300 or 400 salamanders migrating throughout the night.
They usually do six counts per annual season.
During the Tuesday night count, Lilly’s father Zach, found another Small-mouthed salamander, and waited for his daughter to return with a ruler. He encouraged her to measure it herself.
“It's a nasty, rainy night, and what else are you gonna do but watch TV,” he said. “Might as well go out and do something fun … instead of staring at screens and and learn something in the same time.”
Walsh said these counts also teach volunteers about conservation of natural resources.
“It's also a way to develop a greater appreciation for the salamanders themselves, but also the ecosystem as a whole,” he said.
- Wesselman Woods staff and volunteers spot and measure salamanders. (Tim Jagielo/WNIN News)
Nathan Engbrecht is the herpetologist with the Indiana DNR. He said there's little data available statewide on amphibian population. This is at least partially because they’re harder to study.
“Salamanders spend most of their year underground or underwater if they live in lakes and streams, and so they're hidden," he said. "And I honestly think historically, a lot of science focused on more charismatic species, the larger species, like maybe wolves or birds or bears and organisms like that. In recent years, we've definitely seen an increase in interest for studying amphibians and reptiles the study of herpetology.”
He said amphibians also live in a wide variety of ecosystems.
As a whole, numbers are staying steady though there have been declines in the past. The Hellbender salamander is one example of a species experiencing declines.
