MARSHALL - There are 11 known species of frogs and three species of toads that live in Minnesota, and the state Department of Natural Resources is calling for volunteers willing to learn how to recognize them by their calls.
Frogs and toads are closely related species. The difference is frogs generally stay near water during their life cycle while toads migrate upland and onto drier ground. Each species of frog and toad uses a distinct call to attract females of their kind.
Volunteers of the annual Minnesota Frog and Toad Calling Survey (MFTCS) have been collecting data and identifying frog species by their calls since 1996. Starting in 2006, the DNR began cooperating with the North American Amphibian Monitoring Program.
"The purpose of the survey is to get a sense of each species, what ranges it inhabits and whether the population is expanding or contracting," said Heidi Cyr, frog and toad survey volunteer coordinator.
Frogs and toads are an integral part of the food chain, especially in lakes and streams, according to Cyr. Tadpoles feed on algae, and when they metamorphose into frogs and toads, carry the nutrients out of the lakes unto the land. They feed on insects, helping control insect populations, and are in turn food for birds and fish.
"In addition to assessing the population status of frogs and toads, many species are known to be sensitive indicators of habitat quality and watershed health," said Lisa Gelvin-Innvaer, non-game wildlife species manager for DNR Region 7. "They're like the early-warning canaries. Things that affect frogs and toads affect other wildlife and also people."
The DNR would like to know more about the distribution of frog and toad species in different locations around the state. It schedules nighttime listening surveys on three evenings between April and July. The three listening surveys are distributed throughout the spring and summer months to record seasonal variations among calls.
Volunteers travel a 10-stop route equipped with a kit, which includes a CD with recorded calls of Minnesota frog and toad species and a poster showing the species.
"Volunteers go out on survey to listen to see which species are calling non-stop, calling intermittently, or just one or two calls," Cyr said. "New surveyors get a CD of frog and toad calls and take a quiz annually to identify calls of different species."
Within Lyon, Lincoln and Yellow Medicine counties there are two unclaimed routes available near Ivanhoe and St. Leo. Out of 250 available routes, the DNR usually manages to fill about 200. Routes in the southwestern part of the state are particularly hard to fill, but volunteers who agree to work these routes get first call on their preferred routes as they become available.
"Several volunteers take different routes every year and may stay at a local camping ground," Cyr said. "Some like routes closer to home."
The survey is supported largely through the non-game wildlife checkoff on state tax returns. Anyone wishing to volunteer can find information at the MFTCS page at the DNR website www.dnr.state.mn.us/volunteering/frogtoad_survey/index.html. One can listen to frog and toad calls on the site and take a quiz.
"It's a fun way to get involved and to make a difference," Gelvin-Innvaer said. "Citizen science is so important and without volunteers it simply wouldn't be possible."