It was developed from a training tape used by volunteers from the atlassing project. The CD includes calls of the nine species of frogs and toads that are most commonly heard in Maine. Male frogs and toads sing in the spring and summer mostly to attract mates. Some of them have a more extensive repertoire than others. Spring peepers, for instance, have a bird-like peep to lure females, a rising trill to warn other males away, and a squeaky rain call.
American toads have a long, melodic trill that belies their urgency at finding a mate.
Male bullfrogs frantically looking for a female are notorious for grabbing onto anything. Also included on the CD are examples of mixed-species choruses recorded in different parts of spring and summer. And then, just to make sure you've been listening, the CD ends with a test. The listener has to pick out all of the different species singing in a chorus. They decided to include it on the CD after discovering that their volunteers had started listening to their training tapes in late winter, longing for an early spring.