To the native of river bottomlands and marshes, or a countryside with prairie ponds and woodland pools, there is no sweeter music than the choruses of frogs and toads in spring. On warm nights, on rainy or cloudy days, even in bright sunlight, they join in an off-key clamor until the air fairly throbs with sound. Their calls are difficult to describe or compare with other sounds. The distinctive mating call of the male usually is made by pushing air out of the lungs into the mouth and, from there, through an opening on each side of the tongue to inflate the balloon-like sac or sacs which serve as a resonator. As the animal rhythmically pumps away, the throat sac swells and collapses like a toy balloon, or like a wad of bubble-gum from the mouth of a small boy.
Some kinds have a sac on either side of the head.
With some, like the Gopher Frog, the whole body swells. This singing is always done with the mouth closed and some kinds, notably the pickerel frog, can even croak under water. Around Chicago in March, soon after the ice is gone, the inch-long Cricket Frogs come out of hibernation and chirp by the hundreds and thousands in lakes, ponds and pools. The Leopard Frog utters a long quavering guttural note followed by a few short grunts. Toads, too, sing love songs after they leave their winter burrows and congregate in ponds to breed.