Motor control of song and song-like vocalizations in the white-crowned sparrow

Oscine songbirds show remarkable diversity in song organization spanning from long songs composed of many different syllables to short single songs. All of these likely arose through sexual selective forces and therefore are thought to reflect a singer's skill, often described as vocal performance. It is therefore important to gain insight into the song production mechanisms in species that sing a single, short song. Here we investigated the physiological control underlying learned song and other song-like vocalizations in the white-crowned sparrow (Zonotrichia leucophrys) by recording air sac pressure, tracheal and bronchial airflow and sound during spontaneously generated vocal behavior in 19 males (11 tutored, 8 untutored). The left side of the syrinx tends to produce more contributions to most song syllables than the right side, while both sides generate similar and overlapping frequency ranges and interact in the production of buzzy syllables. Two other song-like vocalizations, trills and twitter song also require sophisticated respiratory and syringeal movements. Trills display the most rapid temporal pattern with mini-breath rates of > 20 Hz. This illustrates that vocalizations other than typical song can also inform us about vocal performance. The basic production mechanism and syringeal lateralization was consistent between tutored and untutored birds, as well as across the different vocalizations studied here, suggesting innate development of the respective contributions of the two sound sources.