Structure, Sequence and Evolution of Song Elements in Wild Australian Zebra Finches

Songs from 402 Zebra Finches (Taeniopygia guttata castanotis) were sampled in order to describe the structure of the song phrase and the relationship of its elements to the call repertoire. The song of wild birds was also compared to that of 47 domesticated Zebra Finches from two European laboratories in order to examine the effects of domestication on song structure. The stereotyped phrase, which is the repetitive unit of the song, had a mean number of 6.75 elements and a mean duration of 0.86 s in wild birds. Elements were sung in sequence that defined three parts to the phrase-a start, a middle and an end. Fourteen types of elements were identified of which four were sung by the vast majority of males; three of these "primary" elements were "borrowed" unmodified from the call repertoire, and formed the start and end sections of the phrase. "Secondary" elements, which were less frequently represented across males, constituted the middle of the phrase and appeared to be modified versions of the Distance-call Element, the loudest element in the phrase. I tentatively conclude that Zebra Finch song may have evolved from the calls associated with flight intention and take-off. Domestication has led to changes in element morphology, frequency of occurrence, and rate of singing (elements/s), but not in number of elements per phrase.