[Differences in vocalization and morphology of the syrinx between Carrion crows (Corvus corone) and Jungle crows (C. macrorhynchos)].

Abstract

The vocal characteristics and the morph of the syrinx in Carrion crows (Corvus corone) and those in Jungle crows (C. macrorhynchos) were compared. The vocalizations of both species of crow were recorded into sonograms and analyzed. The appearance and inner configuration of the syrinx were observed using stereoscopic microscope. In addition, the inside diameter of the syrinx, the sizes of the labia and the attached position of the syringeal muscles were measured. The attached figures of syringeal muscles were different between the two species. The vocalizations of Carrion crows were noisier than possibly because their labias were noticeably smaller than those of Jungle crows. The attachment patterns of the syringeal muscles in Jungle crows suggested that they allow for more flexibility on the inside structure of the syrinx. The inner space of the syrinx in Jungle crows was also wider than those of Carrion crows. These results suggested that Jungle crows may be able to make various vocalizations because of these morphological characteristics.