Figure 2.

Spectrograms of crows produced by adult male Japanese quails. (a–c) Three stages of crow development recorded in the same bird. (a) First crow produced by the quail in its life. (b) First segmented crow. (c) Complete form recorded at the end of the experiment. (d–f) Complete forms of crows recorded from three different individuals at the end of the experiment. S1–S3, measures of the duration of syllables 1–3; T12–T13–T23, measures of the intersyllabic gaps, TD, measure of the total duration of the crow. The dashed line aligns the different crows at the beginning of the final trill, thereby illustrating changes (within individual) and/or differences (between individuals) in the temporal structure of the Japanese quail crow.