Seasonal-like variation in song control system volume of wild zebra finches

Zebra finches have been extensively used as a model system for studying the underlying neuroplasticity that allows for song learning during development. Zebra finches are considered age-limited or close-ended learners, in which fixed songs are learned within a certain window of time during development. In addition, they breed more or less continuously in laboratory conditions. As a consequence, less attention has been paid to potential neuroplasticity in adults. We present data on free-living zebra finches from two populations in Australia (one just beginning a period of breeding and another during a non-breeding period) that show a distinct difference in the volumes of two song system nuclei (HVC and Area X) depending on reproductive state. This is the first study to measure song system volumes in wild zebra finches, and suggests that the potential for neuroplasticity remains in adult zebra finches.