Table 1

Criteria used to assign a qualitative developmental score to songs produced by first year male canaries

Developmental score criteria	Song duration	Song structure¹	Syllable structure²	Repetition accuracy³
Early subsong, score = 1	>0.5 s	No	Not clearly discernable	No
Advanced subsong, score = 2	>1.0 s	No	Not clearly discernable	No
Plastic song, score = 3	>0.5 s	Structure starts to appear	Not clearly discernable	No
Advanced plastic song, score = 4	>0.5 s	Apparent structure	Some syllables discernable	Some phrases accurately repeated
Crystallized song, score = 5	>0.5 s	Apparent structure	All syllables discernable	All phrases accurately repeated

The developmental score is based on the qualitative evaluation of the song structure, syllable utterance, and syllable repetition accuracy compared with an adult male canary during the breeding season.
↵1 Typical structure of an adult male canary contains different phrases made of syllable repetitions.
↵2 Similar to spectrogram view from an adult song.
↵3 Without visible changes in time-frequency contours between successive renditions within the spectrogram.