INGESTIVE AND VOCAL MECHANISMS IN BIRDS - A PARALLEL

Parrots prepare for vocalization by a vetro-caudal retraction of the l arynx. This laryngeal movement, which ''frames'' vocal sequences, is s imilar to a movement used by pigeons as a preparation for suction drin king. The air-pressure events involved in such movements can trigger i ether suction drinking or vocalization. This suggests a possible evolu tionary link between these ingestive and vocal mechanisms.