Figure 1.

Sonogram of a chaffinch song, showing the different levels of segmentation. The smallest units (dotted lines) are single elements, separated by a brief gap. Two of these form one unit (the syllable, dashed line) that is repeated several times. A series of identical syllables form a phrase. In this song (enclosed by the unbroken line), there are three phrases consisting of brief, several times repeated syllables. This song ends, like many chaffinch songs, with a few elements that show a different spectrographic structure and are often not repeated. The first three phrases together form what is known as the ‘trill part’ of the chaffinch song (indicated by the left arrow), which is followed by what is known as the ‘flourish’ part (right arrow). (Sonogram courtesy of Katharina Riebel.)