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

The structure of the syrinx of male adult and juvenile Collared doves (Streptopelia decuacto) was examined on macroscopical, light- and scan ning electron microscopical level to further knowledge of its function ing. 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 modi fied tracheal and bronchial rings, two pairs of tracheal muscles, name ly the Mm. sternotracheales and Mm. tracheolaterales, a pessulus-like structure and 3 different types of membranes: the lateral and medial t ympaniform membranes and a dorsal tracheosyringeal membrane. A bilater al asymmetry is present in length and height of the primary bronchi. C ombining the anatomical data with the present models of sound producti on suggests that vocalizations are most likely to be produced by mecha nical vibration of membranes. rather than by an aerodynamical 'whistle ' mechanism. Inter-individual variation is found in syringeal structur es that may, directly or indirectly, influence the structure of the pr oduced sound, like the number of tracheal and bronchial rings, the len gth of the tracheosyringeal membrane and characteristics of the latera l tympaniform membranes. Therefore, the possibility exists that inter- individual variation in vocalizations is the result of differences bet ween individuals in the structure of the syrinx. Tile syrinx of juveni les, 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.