By Bob Suchanek
It's spring in Minnesota and frogs and toads are seeking other frogs and toads. Love is in the air! With warm spring nights and days, the waters and wetlands are alive with passionate songs; a veritable amphibian choir. You are, of course, welcome to attend, but to fully appreciate the program some familiarity with the vocalists is advised.
There are only 12 species of frogs and toads in all of Minnesota; fewer species are found regionally and locally. If you listen, you can quickly learn to recognize your neighborhood frogs and toads.
I've found that verbalizing what each call sounds like is a great mnemonic device and makes conversations about who's singing easier. So, with the help of the book Amphibians & Reptiles Native to Minnesota by Barney Oldfield and John J. Moriarty, here are some things to help you recognize the singers in Minnesota's amphibian choirs:
American Toad
Sounds like: 20-30 second high pitched musical trills.
Found in most counties in Minnesota. The sound is described as a high pitched musical trill that lasts around 20 or 30 seconds. The song can be “deafening” when hundreds of singers chime in together.
Great Plains Toad
Sounds like: 20-50 second pulsating mechanical trills.
Found in the western border counties of Minnesota from Marshall County to Rock County and as far east as Nicollet County. The mating call is harsh, pulsating, and mechanical and lasts for 20 to 50 seconds.
Canadian Toad
Sounds like: 8 second musical trills.
Found in western and northwestern Minnesota from the Minnesota River in Lac Qui Parle County north through the Red River valley. Their calls are similar to American Toads but the trill is much shorter; from 2 to around 8 or 9 seconds.
Northern Cricket Frog
Sounds like: clicking ball bearings.
These frogs have been heard in the southeastern and southwestern counties of Minnesota but there's some question about their current presence in Minnesota. Oldfield and Moriarty described the call of the male as “a glick, glick, glick sound similar to the clicking of ball bearings”.
Gray Treefrog
Sounds like: 1 second high pitched trills.
Found in most of Minnesota except for the southwest corner. These frogs call from the trees above ponds! The mating call is a series of short (about 1 second) trills. Some listeners mistake treefrog calls for an unspecified insect call.
Cope's Gray Treefrog
Sounds like: 1 second high pitched metallic trills.
Records indicate their presence in the central third of Minnesota where they frequent woodland edge habitats, prairie edges, and oak savannahs. Like the Gray Treefrog, these frogs call from the trees. The mating call is a series of short (about 1 second) trills similar to the Gray Treefrog's but with a metallic edginess.
Spring Peeper
Sounds like: high pitched peeps.
A familiar harbinger of spring, peepers are found in Minnesota's “nonprairie” counties. Oldfield and Moriarty describe the the call as “a high pitched peep or ping. Large choruses sound like sleigh bells and can be deafening when heard up close”.
Western Chorus Frog
Sounds like: strumming the teeth of a comb repeatedly.
Found in most counties in Minnesota, they appear in many wetland habitats and are common urban callers. The sound is accurately described as “similar to the sound made when running one's thumb down the teeth of a comb”.
Bullfrog
Sounds like: “jug-a rum” over and over.
In Minnesota the natural distribution is south of Winona along the backwaters of the Mississippi. Introduced populations have been heard in Blue Earth, Chisago, Jackson, Stearns, and Washington counties. The male's call is a deep baritone “jug-a-rum”.
Green Frog
Sounds like: plucking an out of tune banjo.
Found in the eastern half of Minnesota from Koochiching county in the north to Houston county in the souteast. Green Frogs have a startling “plunk” call that sounds like someone plucking an out of tune banjo.
Pickerel Frog
Sounds like: soft, low-pitched snores.
These frogs are restricted to the southeast corner of Minnesota, including Goodhue, Winona, and Houston counties. The call is a soft, low-pitched snore.
Northern Leopard Frog
Sounds like: low snores with grunts and squeaks.
There are Northern Leopard Frogs in every Minnesota county. The call has been described as “a low snore mixed with resonant grunts and squeaks”.
Mink Frog
Sounds like: pulling a stick along a picket fence.
Northern Minnesota frogs with a distinctive “knock-knock-knock” call that sounds like someone pulling a stick along a picket fence.
Wood Frog
Sounds like: a quacking duck.
Found all over Minnesota except for the southwestern corner. The call sounds like a quacking duck. Oldfield and Moriarty observed that a chorus of Wood Frogs “sounds similar to a group of feeding mallards”.
There are good sites online that offer expertly recorded frog calls. The Minnesota Department of Natural Resources site is focused on state amphibians: https://www.dnr.state.mn.us/reptiles_amphibians/frogs_toads/index.html
The most comprehensive call collection that I've found:
https://www.pwrc.usgs.gov/frogquiz/index.cfm?fuseaction=main.lookup