Fooling the experts: accurate vocal mimicry in the song of the superb lyrebird, Menura novaehollandiae

• Published in: Animal behaviour Vol. 83; no. 6; pp. 1401 - 1410
• Main Authors: Dalziell, Anastasia H., Magrath, Robert D.
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01.06.2012; Harcourt Brace Jovanovich Ltd
• Subjects: acoustic properties; Animal behavior; Animal communication; bioassays; Birds; birdsong; Evolution; experts; males; Menura novaehollandiae; mimicry; Nonnative species; rejection threshold; repertoire; sexual signal; signal design; song learning; vocal accuracy; vocal mimicry; Menura novaehollandiae; rejection threshold; mimicry; repertoire; vocal accuracy; vocal mimicry; sexual signal; birdsong; signal design; song learning
• ISSN: 0003-3472; 1095-8282
• DOI: 10.1016/j.anbehav.2012.03.009

The degree of resemblance between mimics and models provides valuable insight into the evolutionary dynamics of mimicry signalling systems, but for many systems mimetic resemblance has not been quantified. Superb lyrebirds have a reputation for accurately imitating an astonishing variety of sounds that they incorporate into their sexual displays. We assessed the accuracy with which males imitate the complex song of the grey shrike-thrush, Colluricincla harmonica. We measured vocal accuracy by (1) using playback experiments as a bioassay, to determine whether and how shrike-thrushes distinguish between their own song and imitations of shrike-thrush songs by lyrebirds and (2) comparing acoustic properties of mimicked and model songs. Shrike-thrushes reacted just as strongly towards mimetic song as to their own when songs were presented alone. When mimetic song was accompanied by lyrebird song sequences (emulating the lyrebird's natural singing style), shrike-thrushes still usually approached the speaker but less often than when mimetic song was presented alone or when model songs were broadcast. Acoustic analyses showed that imitations were remarkably similar to model songs. However, while lyrebirds maintained the structure and complexity of model songs, they sang fewer repetitions of individual element types. This ‘abridging’ of model songs is consistent with a trade-off between demonstrating both mimetic accuracy and versatility. Overall, these results indicate strong selection on male lyrebirds to imitate accurately the complex vocalizations of other species, and show that species can integrate contextual information with the signal structure to distinguish between their own signals and imitations. ► We measured the accuracy of male lyrebird imitations of another species' song. ► Mimicry was so accurate that even the imitated species rarely picked copies. ► Acoustic analysis showed that imitations were almost indistinguishable from models. ► Despite copy accuracy, lyrebirds abridged songs by reducing repetition of notes. ► We suggest highly discriminating lyrebirds select for accurate mimicry.