Meeting Abstract
Obligate avian brood parasites lay their eggs in the nest of a heterospecific host leaving juveniles without exposure to conspecifics during critical developmental periods. One mechanism by which these juveniles learn to recognize conspecifics is by using a password, typically an unlearned vocalization that cues species recognition. The purpose of the experiments presented here were to explore the neural basis of the password hypothesis as a mechanism of mis-imprint avoidance. We found that adult cowbirds, Molothrus ater, show greater expression of the activity dependent immediate early gene ZENK in two auditory forebrain regions, the caudomedial nidopallium (NCM) and the caudomedial mesopallium (CMM) in response to cowbird chatter relative to a heterospecific control. Juvenile cowbirds showed greater ZENK expression in response to chatter only within the NCM. Our second study also revealed that juvenile cowbirds have greater ZENK in CMM in response to song that was recently experienced, either heterospecific or conspecific. Thus, in juvenile male cowbirds there is early onset of species-specific selective neural representation of non-learned calls in NCM and recently experienced song in CMM. These results suggest NCM was evolutionary co-opted to recognize the species-specific chatter whereas neural signatures of song memory (even heterospecific songs) reside in CMM.
