<ril in Minnesota brings an entire set of new sounds—the rumbling of the first thunderstorms of the year, the whir of a passing frisbee, the chorus of birds celebrating the end of a long winter. But there is a particular spring sound that many Carls fail to notice, or at least to recognize: that of Carleton’s frogs and toads.
There have been eight different species of frogs and toads observed in the Arboretum to date, each with their own unique sound. This past week, the Cole Student Naturalists set out to determine the status of the Arb’s frog and toad population by taking a survey of them. In doing this, those who manage the Arb can make decisions about the management of frog and toad habitats in order to foster these creatures.
Two common frogs found in the Arb are the Chorus Frog and the Leopard Frog. On pleasant summer evenings you might hear them around watery habitats such as Kettle Hole Marsh in the Lower Arb, the Lyman Lakes, Spring Creek in the Upper Arb, and areas along the Cannon River Watershed.
Male frogs make their calls during their breeding season, and some frog calls are so loud that they can be heard from up to a mile away. Frogs make their calls by passing air through the larynx in the throat, a sound that, in some species, is amplified by vocal sacs under the throat. Leopard frogs make a short, snore-like call. They are fairly large in size, reaching about 11 centimeters in length in adulthood, and they are greenish brown in color with dark, circular spots on their backs and legs. Though small (only about four centimeters long—small enough to sit on a dime!), Chorus frogs are some of the louder frogs in the Arb. Take a night walk by Kettle Hole Marsh and most likely you’ll hear them, though because of their rasping, trill-like sound, they can be mistaken for insects by the uneducated listener.
So, take advantage of these warm spring nights: take a walk, look at the stars, and listen for the unique chorus of the Arboretum amphibians.
