Quantitative Tools for Examining the Vocalizations of Juvenile Songbirds
Figure 2
(a) Spectrogram of a juvenile’s vocalizations produced during the babbling phase, at approximately 36 days posthatch. Note the general lack of stereotypy. (b) Spectrogram of a juvenile’s vocalizations produced during the early plastic song phase, at 41 days posthatch. (c) Spectrogram of a juvenile’s vocalizations produced during the plastic song phase, at 47 days posthatch. Although the sounds are more adult-like in terms of spectral profile, they still lack the stereotypy of adult birds. (d) Composite spectrogram of a series of calls from a juvenile zebra finch (40 days posthatch). By eye and by ear, these are easily differentiated from adult song.
