Sex differences in amplitude regulation of distance calls in Bengalese finches, Lunchula striata var. domestica

Many animals regulate their vocal amplitude in relation to environmental noise levels. This behaviour is important both for maintaining auditory feedback and for long distance communication. In this experiment we asked two specific questions. Firstly, does the Bengalese finch, a species of songbirds that critically relies on immediate auditory feedback for its vocalisations, change the amplitude of distance calls against noise? Secondly, if it does, is there any difference between the sexes in the degree of amplitude regulation? To answer these, we recorded distance calls of male and female Bengalese finches under various noise conditions and compared amplitude regulation between the sexes. Results suggest that the finches do show amplitude regulation and that the degree of compensation is much stronger in males than in females. Results are discussed in view of the sex differences in neural mechanisms and the function of distance calls in this species.