Call production induces motor-driven ZENK response in the song control system of black-capped chickadees

Imitative vocal learning has now been described in a variety of taxa, but is most extensively studied for birdsong learning. However, songbirds produce a variety of songs and calls that also are learned. For example, black-capped chickadees, Poecile atricapillus, produce a variety of highly complex learned vocalizations that they use in different contexts. The role of the neural song control system, including the HVC and the robust nucleus of the arcopallium (RA), in the production of chickadee calls is unclear. In this experiment, birds were housed in different conditions to elicit fee-bee songs and gargle, chick-a-dee and tseet calls. The birds were exposed to different stimuli (i.e. a novel live chickadee, a stuffed saw-whet owl, Aegolius acadicus, a mirror, or long-day photoperiods) and their behavioural and vocal responses were recorded. Brains were then processed to label immediate early gene (ZENK) immunoreactivity. In both HVC and RA, the gargle call elicited the most ZENK immunoreactivity. Although the fee-bee song is well established to depend on imitative vocal learning, its production did not induce the most motor-driven ZENK. These findings suggest that activity in the song control system may be more closely correlated with the acoustic complexity of learned vocalizations than with the extent of imitative learning required during development. These findings, and those of earlier studies, indicate that the neural circuit commonly referred to as the ‘song control system’ is better described as a vocal control system for learned vocalizations.