Greater song complexity is associated with augmented song system anatomy in zebra finches.

We revisited the relationship between brain anatomy and song behavior in zebra finches. Consistent with previous studies in other songbirds, we find that differences in volume of the telencephalic song control nucleus HVc is predictive of differences in repertoire size and phrase duration in zebra finches. We extend the study of brain and behavior correlations in song birds by showing that repertoire size in zebra finches can be predicted by variance in several brain nuclei, providing the first demonstration that volumetric differences across multiple components of a neural network are predictive of song behavior.