Song Learning in Song Sparrows: Relative Importance of Autumn vs. Spring Tutoring

We examined 'late' song learning in song sparrows (Melospiza melodia), i.e., song learning that occurs after the first few months, or classical sensitive period, of the natal summer. Fledgling juveniles were brought into the laboratory at 2-3 mo of age and exposed to computer-simulated song tutors in three different time periods: late in the natal summer, the autumn, and the next spring. As expected, the birds' final repertoires consisted mostly of songs heard in the field, but 30% of the birds' songs were influenced by songs heard in the laboratory (selective retention) and another 8% were learned de novo in the laboratory. Parallel results were obtained for a second group of birds who received laboratory tutoring only in the spring. In fact, the results suggested that autumn tutoring may even be inhibitory. We conclude that the songs a young song sparrow hears in his first spring may be critical to his final repertoire development, indicating that the song learning process in song sparrows is longer and more flexible than previously supposed.