THE SYRINX OF THE COLLARED DOVE (STREPTOPELIA DECAOCTO) - STRUCTURE, INTER-INDIVIDUAL VARIATION AND DEVELOPMENT

摘要

The structure of the syrinx of male adult and juvenile Collared doves (Streptopelia decuacto) was examined on macroscopical, light- and scanning electron microscopical level to further knowledge of its functioning. Several syringeal structures were measured in adults to determine the degree of inter-individual variation. Also, a comparison was made between the syringes of adult and juvenile individuals. The syrinx of the Collared dove is of the tracheobronchial type, consisting of modified tracheal and bronchial rings, two pairs of tracheal muscles, namely the Mm. sternotracheales and Mm. tracheolaterales, a pessulus-like structure and 3 different types of membranes: the lateral and medial tympaniform membranes and a dorsal tracheosyringeal membrane. A bilateral asymmetry is present in length and height of the primary bronchi. Combining the anatomical data with the present models of sound production suggests that vocalizations are most likely to be produced by mechanical vibration of membranes. rather than by an aerodynamical 'whistle' mechanism. Inter-individual variation is found in syringeal structures that may, directly or indirectly, influence the structure of the produced sound, like the number of tracheal and bronchial rings, the length of the tracheosyringeal membrane and characteristics of the lateral tympaniform membranes. Therefore, the possibility exists that inter-individual variation in vocalizations is the result of differences between individuals in the structure of the syrinx. Tile syrinx of juveniles, although having a similar basic structure, differs significantly from the adult syrinx with respect to the tracheal and bronchial rings, the tracheosyringeal membrane and the tracheal epithelium. From the moment of hatching, the syrinx develops gradually into its adult form and shape, which is reached at the age of 12-16 weeks.