Why Do Frogs Croak?
In most species of the frogs only the males croak. The male frog croaks in order to attract the female frog during the mating season.
When a frog is ready to croak, it takes a big gulp of air that puffs out either one large or two small sacs (like balloons) under its throat. Then it closes its mouth and pumps the air back and forth between its lungs and mouth.
A puffed-up air sac acts as a resonator, boosting the volume of each croak. As the air moves, it vibrates the vocal cords in the frog’s throat. The vocal sac helps to make the sound much louder.
The louder a male frog croaks the more likely he is to attract a partner. Each kind of frog has its own mating call, which the female can distinguish from the other types of frogs in the pond.