Song cultures in colonies of domesticated zebra finches ( Taeniopygia castanotis ) founded with males experimentally trained to sing the same song

Empirical investigations on communication systems in non-human animals have provided significant insight into the evolutionary origins of language. To further explore how vocal culture may influence such processes, we artificially reduced the vocal diversity found in a colony of zebra finches (Taeniopygia castanotis) by creating three different colonies with founder males trained to produce the same song. Zebra finch song is hierarchically organized: a song bout is composed of one or several song motifs sometimes interspaced by call-like syllables, each motif being composed of a few syllables repeated in a fixed order. We found that most males that hatched in those colonies conformed to the original song motif even if the overall similarity tend to decrease over time. They also introduced some vocal innovations such as syllable recombination mainly at the macrostructural level of song, namely the song bout. By constraining the acoustic diversity of song models at the foundation of colonies of zebra finches, we succeeded in creating artificial song cultural lineages. We show that vocal production learning, through imitation and innovation, can shape a vocal signal differently at different levels of its structure and maintain vocal polymorphism, a process reminiscent of what is proposed for language evolution.