Effects of isolation rearing on the development of the distance calls in male Bengalese finches (Lonchura striata var. domestica)

Abstract

Distance calls of adult Bengalese finches show sexual dimorphism. The calls of females are widebanded and pulsed, while those of males are narrow-banded and continuous. In an earlier study, it is revealed that this dimorphism appears during ontogeny [Yoneda and Okanoya, J. Ethol.9 , 41–46 (1991)]. Both males and females were emitting female-type calls at an early stage, but male calls begin to show structural changes around day 40–55 and then gradually crystallize into male-type calls until around day 90. In this study, male Bengalese finches were raised normally until day 23 and then isolated from adult conspecifics. The development of the distance calls of these birds was studied. Isolation-reared birds started emitting male-type calls at around day 50–60, but the call remained uncrystallized. It is suggested that the sensory learning of an external model is necessary for establishing crystallized adult male distance calls in Bengalese finches. [Work supported by a Fellowship from the Japan Society for the Promotion of Science.]