Volunteers document frogs, toads
Wisconsin’s largest frog appears to be staging a comeback.
That’s a welcome trend documented over the last generation by hundreds of volunteers who’ve travelled roads near rivers, lakes and wetlands listening for the breeding calls of male frogs and toads.
The Wisconsin Frog and Toad Survey will get underway in the coming weeks and volunteers are likely to hear more of the booming call of the American bullfrog this summer when its mating season begins.
Ranging from 3 1/2 inches to 8 1/2 inches from snout to vent, the American bullfrog is the largest frog in Wisconsin and North America and has a foghorn call to match, said Andrew Badje, a state Department of Natural Resources conservation biologist who coordinates survey volunteers.
“Our volunteers are increasingly reporting more bullfrog calls since the Wisconsin Frog and Toad Survey began in 1984,” he said. “That’s great news for several reasons. While American bullfrogs are considered a pest in western states where they’ve been introduced, they are native to Wisconsin and a valuable part of the food chain. Their comeback also shows we can take protective actions and make a difference.”
Bullfrogs were widely used in the 1900s for biological supply companies, the bait industry and for use in the food industry as frog legs.
DNR regulations have helped prevent the overharvesting of adult bullfrogs in Wisconsin and have helped the population build again, as have increased conservation education efforts from the agency’s Natural Heritage Conservation program and several partners.
The Wisconsin Frog and Toad survey began in 1981 as a response to known and suspected declines in the 1960s and 1970s in numerous Wisconsin frog species, including the northern leopard frog, American bullfrog, pickerel frog and Blanchard’s cricket frog.
A dedicated volunteer base has made the survey the longest-running citizen science amphibian calling survey in North America, according to Badje.
“Over the years, these citizen scientists have helped DNR conservation biologists define the distribution, status and population trends of all 12 frog and toad species in the state,” he said.
Volunteers have logged more than 8,700 survey nights and 87,000 site visits since the survey began. Their data have documented the American bullfrog’s good news in Wisconsin, but also a downward trend for the northern leopard frog over the course of the survey. Spring peepers, boreal chorus frogs and green frogs have been on more stable paths since the survey began.
Volunteers survey three nights a year along a pre-set route in early spring, late spring and early summer. Each volunteer makes 10 stops per night – five minutes at each site – and documents the species calling and the relative abundance of each species.
A few survey routes for 2018 are not yet spoken for. Available routes can be found at wiatri.net. Interested volunteers also can ask survey coordinators about open routes or to be placed on a waiting list for future years as desired routes or counties become available.
Volunteers also are invited to participate in phenology surveys to help monitor when frogs and toads first start calling. Phenology volunteers choose one wetland to monitor throughout the frog-calling season and record data as often as possible for five minutes per night.