Frogs are small and sometimes have to travel great distances to their breeding ponds. Many of them bypass the ponds with fish in them, for the frogs that try to breed there will not last very long. They may return to the pond where they were transformed from tadpoles, or they will be drawn to another place where they hear the voices of others calling.

The problem is frog fidelity - not to their mates but to their breeding sites, to which they return year after year. The longest migrations are recorded in Eastern Europe, where some frogs travel as far as 15 kilometers (9 miles). It’s difficult to change such deeply programmed directions; common toads have returned to parking lots. Although this is certainly not true for all frogs. Many species visit different locations in a single breeding season.

Many species begin to move when the rains begin or just before in responses to changes in air pressure that signal the rain to come. Depending on where they live, the trigger could be the start of the tropical rainy season, the spring showers and the melting snow of the temperate zone, or the deserts summer thunderstorms. A few species may already be at the pond having spent the winter in saturated muck at the bottom.

The males normally arrive first and set about establishing territories in shallow water. The females wait patiently for the great courtship ritual to begin. Let the songs begin! Now to the uninitiated, this cacophony might seem to be produced by some unmusical chorus of aliens. In the simplest terms however, it is a grand assemblage of males shouting “pick me”. Each version is the product of the frogs vocal cords, greatly augmented by the air sacs in its throat. When the sacs expand in the air, they broadcast the sounds, making the sound call of some species audible kilometers away.

By forcing air into the sacs from the lungs and then from the sacs back into the lungs, frogs use their sacs like bagpipes, allowing them to call continuously, even underwater. A few species that lack the vocal cords still call, however their calls can only be heard a few meters away. The vocalizations provide other frogs that are listening information about the size and health of the caller.
Males near one another commonly call in duets, trios or other small groups. It may be the dominate male of the group who calls first, followed at brief intervals by the males in the chorus. This allows the males to get their message across without being drowned out by the others.