Male superb lyrebirds mimic functionally distinct heterospecific vocalizations during different modes of sexual display

Abstract

Mimicry has long been a focus of research, but little is known about how and why many species of bird incorporate imitations of heterospecific sounds into their vocal displays. Crucial to understanding mimetic song is determining what sounds are mimicked and in what contexts such mimicry is produced. The superb lyrebird, Menura novaehollandiae, is a large oscine passerine with a lek-like mating system. Both sexes are accurate and versatile vocal mimics of the vocalizations of other species, but little is known about how males deploy their repertoire of mimicked sounds across contexts. Using extended focal watches, we recorded adult males displaying during the breeding season. We found that males mimicked heterospecific songs and nonalarm calls during ‘recital’ displays usually performed while they were perched and visually inconspicuous. In contrast, during visually conspicuous ‘dance’ displays, commonly performed on display mounds, males only mimicked heterospecific alarm calls. While much rarer than recital displays, dance displays were associated with the final stages of mate choice preceding copulation. These results provide the first evidence of any species varying its repertoire of mimicked sounds with different sexual contexts. Previous work suggests that mimicry in dance displays functions deceptively to manipulate the antipredator responses of females during the final stages of courtship. However, the structure and context of recital mimicry closely resembles the sexual advertisement song performed by nonmimicking songbirds. Given the importance of mimicry in the acoustic ecology of lyrebirds, our results suggest that with recital song males advertise the quality of their mimicry as it likely benefits both male and female offspring. Our finding that male superb lyrebirds mimic functionally distinct heterospecific vocalizations during different modes of courtship suggests that the evolution and maintenance of avian vocal displays are more complex than previously thought.