Transcriptomics of auditory forebrain in brown-headed cowbirds

How does a naïve young animal decide from which adults to learn behavior? Obligate brood parasitic birds, including brown-headed cowbirds (Molothrus ater), face a particular challenge in learning species-specific behaviors: they lay their eggs in the nest of another species and juveniles are raised without exposure to adult conspecifics. Nevertheless, male cowbirds need to learn a conspecific song to attract appropriate mates, and female cowbirds need to learn to identify conspecific males for mating. Traditionally, it was thought that parasitic bird species rely purely on instinctual species recognition, but an alternative is that a species-specific trait serves as a “password”, a non-learned cue for naïve animals that guides decisions regarding from whom to learn. Here, we tested the hypothesis that the adult “chatter call” enhances the learning of specific songs in juvenile cowbirds. We exposed acoustically naïve juvenile male and female cowbirds to songs paired with chatter calls, and found that the chatter call enhanced song production learning in males and induced a neurogenomic profile of song familiarity in females, even for heterospecific songs. Thus, a combination of experience-independent and -dependent mechanisms converge to explain how young cowbirds emerge from another species' nest, yet learn behaviors from conspecifics. Identifying whether such password-based mechanisms relate to perceptual and behavioral learning in non-parasitic taxa will contribute to our understanding of the development of social recognition systems generally.