Fidelity of and biases in the developmental acquisition of song tempo in a songbird

Abstract

The temporal organization of sounds used in social contexts can provide information about signal function and evoke varying responses in listeners (receivers). For example, music is a universal and learned human behavior that is characterized by different rhythms and tempos that can evoke disparate responses in listeners. Similarly, birdsong is a ubiquitous social behavior in birds that is learned during critical periods in development and used to evoke physiological and behavioral responses in listeners. Recent investigations have begun to reveal the breadth of universal patterns in birdsong and their similarity to common patterns in speech and music, but relatively little is known about the degree to which biological predispositions and developmental experiences interact to shape the temporal patterning of birdsong. Here, we investigated how biological predispositions modulate the acquisition and production of an important temporal feature of birdsong, namely the duration of silent intervals ("gaps") between vocal elements ("syllables"). Through analyses of semi-naturally raised and experimentally tutored zebra finches, we observed that juvenile zebra finches imitate the durations of the silent gaps in their tutors song with high fidelity and can "alter" the durations of gaps toward a central duration. When juveniles were experimentally tutored with stimuli containing a wide range of gap durations, we observed biases in the stereotypy but not in the central tendency of gap durations. Together, these studies demonstrate how biological predispositions and developmental experiences differently affect distinct temporal features of birdsong and highlight similarities in developmental plasticity across birdsong, speech, and music.