Water trickling down through the forest leaf litter draws the frost from the ground and gives hibernating frogs their spring wake-up call. Something tells these chilly creatures to head to the nearest shallow pond. For most of our frogs, the pond is only a temporary abode. It serves as the nuptial bed and nursery.
Male frogs do the singing.
Their calls advertise their presence to females and to other males. Each species of frog has its own distinct calls, encompassing an extraordinary range of pitches, tonal qualities, and rhythms. Since singing frogs are usually up to their throats in cold water, identifying them by sight is tough. Coupled with the fact that they generally sing in the dark, it pays to learn their songs so you can tell one croaker from another. Here are my mnemonics clues to frog identities along with the sequence of their calling periods in Hennepin Parks.