This is one CD of a four volume set. I ordered this CD and recieved volume 2. It has 100 birds from willow grouse to sandgrouse. A large percentage are not what I think of as song birds. Lots of chirps and rattles. (I am not a birder). I assume the other 3 CDS have a similar number of birds. This appears to be a set for the serious birder, and not for someone who is looking for a musical treat.