17. The puzzling case of the California thrasher.
3. Why and How Birds Sing
Singing in the brain
From page 34 in the book.
The puzzling case of the California thrasher. It would be fascinating to find where a California thrasher awakes, morning after morning, and listen to (and record) all that he can do. Would he ever return to something he had sung before? If so, how many days of listening would it take to hear some repetition? If never, does he compose original songs each day, settling on some theme that most satisfies him, or has he a seemingly infinite store of set themes to choose from? Thrashers—-what extraordinary singers!