As the performers take the stage, the audience crackles with excitement. Before long, the fans are clapping their hands, singing along and shouting for their favorite songs. One of those old '60s rock groups now on tour? Not quite. The crowd is old enough to be Stones fans, but these tunes are not about getting satisfaction or spending the night together. Instead the two guitarists are singing of spotted owls and acid rain.
The scene is the Sierra Club International Assembly in Ann Arbor, Mich., and the players are Bill Oliver and Glen Waldeck, the poets of preservation and the unofficial...