Genetic and developmental effects, and morphological influences on the acoustic structure of individual distance calls in female Bengalese finches Lonchura striata var. domestica

Recent studies of the vocal mechanisms of songbirds have shown that there are physical effects on sound production. Interspecific and phylogenetic comparisons have shown that body mass and bill morphology are two major factors affecting vocalizations such as songs. We analyzed the distance calls of female Bengalese finches Lonchura striata var. domestica , the non-vocal learning sex, to assess the potential physical effects on the acoustic structure of vocalizations. By experimentally controlling rearing condition using cross-fostering we could examine the effects of the developmental environment and genetic background. None of the tested factors affected the peak frequency of the distance calls, but we found that larger-billed birds tended to produce shorter bout calls with higher trill rates. These results suggest that the divergence of bill morphology can affect acoustic features at the within-population level. We also found that the birds reared in the same foster brood and siblings from the same genetic parents tended to produce calls with similar trill rates. This implies that the trill rate is under the influence of developmental and genetic factors.