Prenatal sound experience affects song preferences in male zebra finches

Songbird vocal learning is a popular model for understanding the evolution of complex communication. When multiple tutors are available, juvenile songbirds prefer to learn vocalizations from some tutors over others, their preferences partly guided by postnatal acoustic experience and social interactions. The potential for prenatal sound to also influence song tutor choice remains largely untested, despite recent evidence that prenatal sound affects other aspects of songbird development. Previously, we showed that Australian zebra finches, Taeniopygia castanotis, learnt more song syllables from nonpaternal tutors if they had previously experienced ‘heat calls’ (parental vocalizations produced at high ambient temperatures) as embryos. This suggests that heat call exposure may trigger changes in offsprings' social behaviour or learning strategy as juveniles, thereby indirectly affecting their song tutor preferences. In this study, we tested this hypothesis by prenatally exposing male zebra finches to either heat calls (treatment) or contact calls (control) and then assessing their song preferences as adults. Song preferences were measured in a four-way choice apparatus in response to playback from four different individuals: their social father (paternal song), an unrelated conspecific (nonpaternal song) and two heterospecifics (both male canaries, Serinus canaria). As expected, subjects were more attracted to conspecific songs than to canary songs, regardless of their prenatal sound exposure. In addition, prenatal sound experience altered subjects' conspecific song preferences: treatment birds preferred nonpaternal conspecific song over their social father's song while control birds showed no preference. That prenatal sound produced long-lasting differences in individual song preferences, which are typically reflective of vocal tutor choice, has implications for understanding both the flexibility of vocal learning and the influence of prenatal soundscapes on individual phenotypes.