Rothenberg, a jazz clarinetist and philosopher with a strong interest in the interconnectedness of things, weaves music, poetry and science in this intriguing series of essays. It's a riff on the meaning and pleasure of birdsong, including, of course, a chapter on the nightingale. He opens the book with an account of a jam session with -- and for -- the birds of the national aviary. This paperback edition includes an accompanying 63-minute CD of music and birdsong.  (BRD23, $19.95)