An Acoustic Password Enhances Auditory Learning in Juvenile Brood Parasitic Cowbirds

• Published in: Current biology Vol. 29; no. 23; pp. 4045 - 4051.e3
• Main Authors: Louder, Matthew I.M., Balakrishnan, Christopher N., Louder, Amber A.N., Driver, Robert J., London, Sarah E., Hauber, Mark E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 02.12.2019
• Subjects: auditory cortex; critical period; imprinting; learning; neuroplasticity; recognition; songbird; auditory cortex; critical period; imprinting; songbird; recognition; learning; neuroplasticity
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2019.09.046

How does a naive, 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 [1–4], but an alternative is that a species-specific trait serves as a “password” [5], a non-learned cue for naive 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 naive 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 converges 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 general understanding of the development of social recognition systems. •Exposure to cowbird chatter calls (“the password”) enhanced song learning in male cowbirds•Exposure to chatter calls in early life induced neurogenomic signatures of plasticity•Songs paired with chatter calls triggered neurogenomic signatures of familiarity•The password provides a mechanism to guide learning of specific songs How obligate brood parasites, which are raised by different host species, recognize and learn phenotypes of their own species remains unknown. Louder et al. demonstrate that a specific non-learned vocalization (the “password”) serves as a cue to initiate the onset of perceptual learning for other socially relevant signals in parasitic cowbirds.