The vocalizations and syringeal anatomy of the common crow, Corvus brachyrhynchos

Abstract

A study of the vocalizations and syringeal anatomy of the common crow was conducted between 1964 and 1966. Intensive documentation of the sounds produced by the common crow, related to the appropriate behavioral context in which each sound occurs in the wild, was the primary objective of this research. Wild crows were tested with recordings of captive and wild crow vocalizations to determine the nature of the important calls and signals of this species. Common crows were also tested with "distress calls" of three sympatric species. The objectives of the syringeal research was to 1) determine how sound is produced by the common crow and 2) work out the anatomy and probable function of the syringeal components in this species. Fifteen "primary vocalizations" were documented in the common crow. They were defined as sounds which caused responses among crows. Twelve “other vocalizations” were documented in this species. They were defined as sounds which caused no responses among crows. All of the vocalizations of the common crow were not documented in this study. Careful dissections of 55 common crows collected in the field revealed that four pairs of bronchial rings, five tracheal rings, one pair of external tympaniform membranes, one pair of auxiliary membranes, and six pairs of muscles are the components of sound production in the syrinx. Probable functions of these and other syringeal parts are discussed.