Acoustical and Syntactical Comparisons between Songs of the White-backed Munia (Lonchura striata) and Its Domesticated Strain, the Bengalese Finch (Lonchura striata var. domestica)

Abstract

The Bengalese finch is a domesticated strain of the white-backed munia. The process of domestication began some 250 years ago in Japan and several modifications in coloration and behavior occurred. We recently found that songs of Bengalese finches are much more complex in their temporal organizations than songs of related species such as zebra finches. We hypothesized that this complexity occurred during domestication. To explore this hypothesis, we compared syntactical and acoustical parameters of songs between the wild and domesticated strains of white-backed munia. Acoustical morphologies of the song elements were strain-specific: similarities among song elements were higher within individuals of each strain, but the degrees of morphological variations were comparable between the strains. In the time domain, white-backed munias sang a highly stereotyped song: a song element was always followed by one of certain song elements in a deterministic way. Bengalese finches, on the other hand, sang complex song with one song note followed by several possible song notes. Male songs should evolve largely under two different pressures: female preference and risk of predation. The low degree of complexity found in wild white-backed munias may be the result of compensating these two factors. In Bengalese finches, because of the domestication, predation is no longer a selection pressure. Thus, it is likely that Bengalese finch songs had undergone changes that were favored by females.