Cassettes are available to help a person learn frog calls, making them easier to identify by sound. Wood and Chorus frogs use shallow sloughs, potholes and road ditches for breeding. They heat up more quickly than lakes. The eggs and tadpoles have to hatch and metamorphose within a few weeks, before the waters dry up. Green Frogs and Bullfrogs only breed in permanent water bodies.
Tadpoles dig into the mud over winter and it takes two or more years to metamorphose into frogs.
Frog calls are used to establish populations of certain frogs in an area. Frog populations help gauge our understanding of the overall condition of the environment on land and in the water. Frogs are a marker of water quality because they lay their eggs in water and spend the early stage of their life in water as tadpoles. Polluted water can kill eggs and tadpoles. Frogs breathe through their skin so even adult frogs can be affected by polluted water.