A Sound Guide to Owls - Ornithology Author:Claus Konig, Richard Ranft This double CD contains the voices of approximately 190 species of owls, representing about 90 percent of the world's species and including many for the first time. It has been produced to accompany "Owls: A Guide to Owls of the World" by Claus Konig, Friedhelm Weick and Jan-Hendrick Becking.