Zebra finch tutees not only share the melody but also the rhythm of their tutor’s song

Recent studies have highlighted rhythmic patterns in the vocalizations of several animal species, particularly in songbirds. Whilst it is known that for instance zebra finches copy the spectral content of their tutor’s song, little is known about possible rhythmic copying. In this study, analyzing the inter-onset intervals of the elements in the motifs of 17 tutors and their 37 tutees shows that rhythms are most similar between tutors and their respective tutees – though only when considering the whole motif produced by the tutee. When examining only shared or only non-shared elements, rhythmic patterns differed. This suggests that the shared rhythm goes beyond copying the temporal features of individual elements; tutees perhaps adjust the rhythm of non-shared intervals, resulting in an overall rhythm resembling their tutors’. Furthermore, tutees who share all elements tend to sing slower, more consistent rhythms, while those who improvise more in elements or melody show greater variability in both rhythmic rate and consistency. This might hint at two distinct evolutionary strategies: one favoring consistent, slower rhythms, the other favoring novelty. Female choice experiments might be the next step to prove this hypothesis.