NEWS-SENTINEL (Knoxville, Tennessee) 02 May 06 Frog days of summer - Volunteers' ears gather amphibians' breeding numbers (Morgan Simmons)
Crossville, Tenn.: It was a clear, moonlit night, and love was in the air.
Matthew Gray, an assistant professor of wildlife at the University of Tennessee, parked the truck along a quiet road in Cumberland County and rolled down the windows. There was a small wetland nearby, and off in the woods a whippoorwill lent its voice to the nocturnal chorus of frogs and toads.
The biggest loudmouths were the spring peepers - tiny tree frogs that mate in late winter and early spring. Calling in unison, their voices swelled to ear-ringing decibels. Collectively, they sounded like sleigh bells.
"What we're hearing," said Gray, "are the breeding males."
All across the state, volunteers are conducting listening surveys to help monitor the breeding populations of Tennessee's frogs and toads. The project - called the Tennessee Amphibian Monitoring Program - is part of an international effort to document the global decline of amphibians.
Gray is the TAMP coordinator for East Tennessee, and with him that night were two undergraduate students and members of the UT chapter of the Wildlife Society, Nathan Haislip and Jeremy Hamlington. They were on a listening route on the outskirts of Crossville, and this was their first stop.
Haislip and Hamlington wore headlamps. Standing beside the road, they identified southeastern chorus frogs mixed in with the spring peepers. In the background, barely audible above the din of the tree frogs, they singled out the soft, drawn-out trill of the American toad.
Haislip disappeared into the night for a few minutes and returned with his hands cupped around an American toad. Based on its vocal sac and darkly pigmented toes, Gray identified it as a male.
"The males pick a spot in the vegetation and fight off other males," Gray said. "They literally do sumo wrestling combat. Then you have satellite males that don't call, but sit quietly and intercept passing females. It's a survival strategy for some individuals."
TAMP volunteers (or "frog leggers" learn to identify frogs and toads by attending free workshops. It's similar to bird watching, but less daunting considering there are 24 species and subspecies of frogs and toads in Tennessee compared to some 175 species of birds that regularly nest in the state.
Now is the time to listen for spring peepers and chorus frogs around backwater sloughs, ditches and puddles. On larger bodies of water, you're likely to hear pickerel frogs and southern leopard frogs. As the weather warms up, the familiar sound of green frogs (imagine a plucked banjo string) and bullfrogs (the proverbial "jug-a-rum" will resonate around lakes and ponds.
"You'll hear frogs and toads throughout the summer, but the species composition will change," Gray said.
Data from the TAMP surveys is expected to shed light on the statewide distribution of various frog and toad species, as well as their relative abundance. Tennessee's monitoring program is relatively new - in a few more years biologists should be able to tell if the breeding populations are healthy or on the decline.
The major threat to Tennessee's frogs and toads is the loss of wetland habitat. Tennessee has an estimated 787,000 acres of wetlands, down from an estimated 1.9 million acres historically for a 60 percent loss. The Tennessee Department of Environment and Conservation has identified 54,811 acres as impaired by pollution or loss of hydrologic function.
Much of the wetland loss comes from channelization and leveeing in the name of flood prevention. Another significant impact is pollution from farm and construction runoff.
The state has a "no net loss" policy aimed at preventing further wetland damage.
All TAMP data is entered into a Tennessee database, as well as into the database of the North American Amphibian Monitoring Program, where it can be searched by route number, date, calling-card index or other criteria.
That night, on a scale of 1 to 3, Gray rated the spring peeper abundance a three because the calls were continuous and overlapping. The American toads received a rating of two because individuals could be picked out among the mass of callers.
There was an eerie synchronicity to the mating calls, as if every anuran within earshot was following the same cue.
"It's pretty straightforward," Gray said. "The males are calling to any females that might be listening."
Volunteers' ears gather amphibians' breeding numbers