Minnesota is home to eleven species of frogs and three species of toads. The calls are made by the males serenading the females after they have awakened from their long winter hibernation. Different breeding seasons and therefore, different calling times throughout the spring can help adjust the learning curve.
Starting in late March, the western chorus frog is one of the early risers of the group. Though small, these frogs can sing extremely loud. Their call resembles that of running your thumb along the teeth of a comb. The wood frog also begins singing this time of year, with a sound like the quacking of a small duck. Another early riser, the spring peeper, is what most people view as the true herald of spring, although it emerges later than the western chorus frog and the wood frog. Like its name suggests, its call sounds like that of a peep, with a large group producing an almost sleigh bell sound.
April brings about the northern leopard frog. This is the most common frog throughout Minnesota and easily recognized by child and adult. They begin to sing when the water temperature nears 68 degrees Fahrenheit. Their song resembles a snoring sound with some grunts and squeaks thrown in for good measure. Also in April, the pickerel frog adds its voice to the chorus. This frog found in the Southeastern part of the state is difficult to hear since most of the calling is done while submerged. Like the northern leopard frog, it also makes a snoring sound.
The toads and treefrogs begin their breeding season around the beginning of May. Toads are easy to differentiate from frogs physically in the fact they are round, dry, bumpy and have short legs. Frogs, on the other hand, are long and sleek, with smooth, wet skin and jump rather than hop. The American toad is the most common toad, found in many gardens and yards. Their high-pitched trill often indicates the beginning of summer. The Canadian toad also emerges at this time with a trill similar to its American cousin, but much shorter. The Great Plains toad doesn’t have the melodic song like the others, but is rather more harsh and metallic sounding.
The gray treefrog and Cope’s gray treefrog also appear in May. Their metallic trill is distinguishable with the Cope’s song faster than the gray’s song. The northern cricket frog also joins the chorus, although they are a rare find in Minnesota. Like their name suggests, their call is similar to a cricket.
The end of May brings about the late sleepers in the group. The mink frog received its name from its smell. Their knock-knock call is heard in the northern part of the state. The green frog is located along the eastern edge of the state. Its loose banjo string call makes it easy to tell from the other frogs. The last frog to breed is the bullfrog. The largest frog in Minnesota, it is a serious predator in the wetlands it calls home. Its deep “jug-a-rum” song is heard throughout June and into July.