Novel motor gestures for phonation during inspiration enhance the acousticcomplexity of birdsong

Sound generation based on a pulmonary mechanism typically occurs during the expiratory phase of respiration. Phonation during inspiration has been pos tulated for the calls of some amphibians and for exceptional sounds in some , human languages. No direct evidence exists for phonation during inspirati on in birds, but such a mechanism has been proposed to explain very long un interrupted songs. Here, we report the first physiological evidence for ins piratory sound production in the song of the zebra finch (Taeniopygia gutta ta). Motor gestures of the vocal and respiratory muscles leading to the pro duction of inspiratory phonation differ from those of silent inspirations d uring song as well as from those leading to phonation during expiration. In spiratory syllables have a high fundamental frequency, which makes them aco ustically distinct from all other zebra finch song syllables. Furthermore, young zebra finches copy these inspiratory syllables from their tutor song, producing them during inspiration. This suggests that physical limitations confine the production of these sounds to the inspiratory phase in zebra f inches. These findings directly demonstrate how novel respiratory-vocal coo rdination call enhance the acoustic structure of birdsong, and thus provide insight into the evolution of song complexity.