Photo by Chris Meyer Block ‘We’d still like to know why some areas that seem like quality habitat have low species diversity. We’d also like to know whether we can properly manage the greenways by regularly measuring frog populations.’ —Lori Block

While still an undergraduate at IU Bloomington, Block became interested in Indy Greenways, a growing network of recreation trails and conservation corridors crisscrossing the Indianapolis metropolitan area. With the guidance of her adviser, Vicky Meretsky, associate professor of SPEA at IUB, and some advice from Greg Lindsey, a SPEA professor at IUPUI, Block set out to determine how successful the corridors had been in preserving and supporting native wildlife.

“When I looked at recent studies of amphibian populations in the area, I found all of them had been conducted in Eagle Creek Park on the northwest side of Indianapolis—all of them,” Block said. “I wanted to know what wetland habitat and amphibian populations were like elsewhere.”

Block, who now works for Indy Greenways as a project assistant and library manager, presented the results of her two-year study of greenway anuran (frog and toad) populations to members of the Indiana Academy of Science at the organization’s 119th annual meeting Oct. 17 at Anderson University.

“Anurans are good bio-indicators because they’re extremely sensitive to their environments,” Block explained. “They absorb everything—air, water, as well as what’s in the air and water. We also know their numbers have been in decline in recent years, and that’s troubling. Frogs have outlasted dinosaurs and pre-industrial man. If they can’t make it anymore, then that’s probably a signal that there’s some degradation on both land and in water.”

To learn whether frogs were making homes in greenways, Block and a hand-picked team of volunteers set out to assess the size of frog populations, describe the places where the frogs were living, and locate frog breeding sites. Block, an expert on anuran calls—or “choruses”—came prepared to identify 14 different anurans, including colorful Fowler’s toads and small, but bombastic, Cope’s grey tree frogs.

The seven greenways constitute more than 150 miles of trails, yet the areas around the trails are often extremely narrow. Classic conservation biology principles suggest such a set-up will have limited success in protecting local populations from becoming extinct.

“After the first couple of weeks, I had found very few amphibians, and that was discouraging,” Block said. “But I kept at it. After many weeks, we found some populations. There’s definitely a challenge to finding them.”

Block said the data she collected suggest the greenways are providing adequate habitat space for some anuran species, but not others. Only four of the 14 anuran species native to the Indianapolis area were abundantly detected—the American toad, the cricket frog, the bullfrog and the green frog. The other species were either rarely found or not found at all. Some species are probably naturally rare, Block said, but others, like the bullfrog, are often as common as urbanized pigeons in Midtown Manhattan.

“Even though the greenways landscape is extremely fragmented, we found there are still some areas of quality habitat,” Block said. “Another big deal is that we found quite a few cricket frogs, which are known to have been disappearing across the northern half of their original range, which includes Indianapolis. We found them in some pretty disturbed areas, too.”

Block says there’s still a lot of work to do. “We’d still like to know why some areas that seem like quality habitat have low species diversity,” she said. “We’d also like to know whether we can properly manage the greenways by regularly measuring frog populations.”

A paper describing Block’s study and results will appear in the next edition of the Proceedings of the Indiana Academy of Science. The publication will be used to forge new partnerships between Indy Greenways and local groups and, Block hopes, to show the city of Indianapolis that the Indy Greenways project is both necessary and worthy of expansion. It’s not just about frogs, she said.

“Healthy wetlands don’t just filter our water and make it cleaner,” Block said. “Wetlands also provide habitat for predators of West Nile-carrying mosquitoes—frogs and toads. Indianapolis has lost a ton of habitat and a ton of wetlands, but I am optimistic. A lot of groups are banding together to restore these areas and put them back together.”

More information about Indy Greenways can be found at:

http://www.indygreenways.org