Figure 5. Unstableness of beginning and end of song bout and their evaluation scores.

(A) Three spectrograms of beginning (left panels) and ending parts (right) of bouts. Several syllables in beginning parts (shown as arrow heads) of introductory syllables (labeled ‘i’) are often weak and unstable. Last syllables located at the terminated part of bout are sometimes shortened and unclear (shown as arrow heads). (B) Percent occurrence rates of evaluation scores that have negative values, at various syllable locations in beginning (left) and ending parts (right). N indicates the location of terminating syllable. Error bars show standard error (n = 13).