Judy Irving's intimate portrait of a San Franciso loner's unlikely love affair with a feral flock of cacophonous cherry-capped conures — clownish, pigeon-sized, bright-green birds — ends with a gentle, satisfying twist. Bearded middle-aged Mark Bittner, who has thick glasses, a long ponytail and "no money, but all the time in the world," pursued a vague dream of rock and roll stardom from Seattle to San Francisco in the late 1970s and never left. He also never sought steady employment, depending on odd jobs and the kindness of strangers to get by, and didn't so much look for his bliss as he waited for it to find him. And wonder of wonders, it did. In the early 1990s,...