In the old folk song/nursery rhyme, Mr. Frog goes courting by strapping on a sword and pistol and riding his horse to Miss Mousie's house.
But on the ponds and wetlands of Minnesota, frogs seem to use a different method.
Spring evenings are when frogs clear their throats and get a good ol' croak on. The state DNR is looking for volunteers willing to estimate how many frog and toad voices are singing that spring song.
The annual survey is a way to measure the health of the amphibians and, by extension, the wetlands and lake shores where they live.
If you're interested you can sign up here.
Of course, you're probably worried you wouldn't be able to tell the call of the Grey Treefrog from the Western Chorus Frog. Fear not, for your friendly state agency will provide you with a CD containing the calls of all 14 species of Minnesota frogs and toads.
Or you can get a jump on your studies by listening to them on this handy frog site compiled by the Pollution Control Agency.