Figure 1. Changes to average song duration and tempo variability over 65-365 dph. A: Spectrogram from bird 257 from 65-85 days old. Each spectrogram depicts the song motif whose duration is closest to average computed for that age. Syllable labels are indicated between motifs. B and C: changes in average duration (B) and tempo coefficients of variation (C) for the same bird over 65-85 days old. Syllable labels correspond with those in A. D-F: median plus/minus SE values for duration (D), tempo variability (E), and tempo coefficient of variation (F) across development. Durations were normalized by subtracting the duration at 365 days old.