An Acoustic Password Enhances Auditory Learning in Juvenile Brood Parasitic Cowbirds.

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.