Elaborate Mimetic Vocal Displays by Female Superb Lyrebirds

Some of the most striking vocalizations in birds are made by males that incorporate vocal mimicry in their sexual displays. Mimetic vocalization in females is largely undescribed, but it is unclear whether this is because of a lack of selection for vocal mimicry in females, or whether the phenomenon has simply been overlooked. These issues are thrown into sharp relief in the superb lyrebird, Menura novaehollandiae, a basal oscine passerine with a lek-like mating system and female uniparental care. The spectacular mimetic song display produced by courting male lyrebirds is a textbook example of a sexually selected trait, but the vocalizations of female lyrebirds are largely unknown. Here, we provide the first analysis of the structure and context of the vocalizations of female lyrebirds. Female lyrebirds were completely silent during courtship; however, females regularly produced sophisticated vocal displays incorporating both lyrebird-specific vocalizations and imitations of sounds within their environment. The structure of female vocalizations varied significantly with context. While foraging, females mostly produced a complex lyrebird-specific song, whereas they gave lyrebird-specific alarm calls most often during nest defense. Within their vocal displays females also included a variety of mimetic vocalizations, including imitations of the calls of dangerous predators, and of alarm calls and song of harmless heterospecifics. Females gave more mimetic vocalizations during nest defense than while foraging, and the types of sounds they imitated varied between these contexts, suggesting that mimetic vocalizations have more than one function. These results are inconsistent with previous portrayals of vocalizations by female lyrebirds as rare, functionless by-products of sexual selection on males. Instead, our results support the hypotheses that complex female vocalizations play a role in nest defense and mediate female-female competition for breeding territories. In sum, this study reveals elaborate female vocal displays in a species widely depicted as an example of sexual selection for male extravagance, and thus highlights the hidden complexity of female vocalizations

Male Superb Lyrebirds (Menura novaehollandiae) perform an ornate multimodal display immediately following copulation

Birds perform some of the most elaborate intersexual displays in the animal kingdom, but while these are typically associated with the pre-copulation stage of sexual interactions, the males of some species also display following copulation. Here we report that immediately after dismounting from females, male Superb Lyrebirds Menura novaehollandiae perform a striking multimodal display comprising a repetitive clicking vocalization and a stereotyped tail posture, while walking backwards away from the female. This ubiquitous postcopulatory display constitutes the fourth, structurally distinct multimodal display performed by male Superb Lyrebirds during intersexual interactions and points to a role for sexual selection after copulation in the lyrebird\u27s lek-like mating system. As such, this study highlights an additional and largely overlooked functional context for complex courtship choreography in birds

Elaborate Mimetic Vocal Displays by Female Superb Lyrebirds

Some of the most striking vocalizations in birds are made by males that incorporate vocal mimicry in their sexual displays. Mimetic vocalization in females is largely undescribed, but it is unclear whether this is because of a lack of selection for vocal mimicry in females, or whether the phenomenon has simply been overlooked. These issues are thrown into sharp relief in the superb lyrebird, Menura novaehollandiae, a basal oscine passerine with a lek-like mating system and female uniparental care. The spectacular mimetic song display produced by courting male lyrebirds is a textbook example of a sexually selected trait, but the vocalizations of female lyrebirds are largely unknown. Here, we provide the first analysis of the structure and context of the vocalizations of female lyrebirds. Female lyrebirds were completely silent during courtship; however, females regularly produced sophisticated vocal displays incorporating both lyrebird-specific vocalizations and imitations of sounds within their environment. The structure of female vocalizations varied significantly with context. While foraging, females mostly produced a complex lyrebird-specific song, whereas they gave lyrebird-specific alarm calls most often during nest defense. Within their vocal displays females also included a variety of mimetic vocalizations, including imitations of the calls of dangerous predators, and of alarm calls and song of harmless heterospecifics. Females gave more mimetic vocalizations during nest defense than while foraging, and the types of sounds they imitated varied between these contexts, suggesting that mimetic vocalizations have more than one function. These results are inconsistent with previous portrayals of vocalizations by female lyrebirds as rare, functionless by-products of sexual selection on males. Instead, our results support the hypotheses that complex female vocalizations play a role in nest defense and mediate female-female competition for breeding territories. In sum, this study reveals elaborate female vocal displays in a species widely depicted as an example of sexual selection for male extravagance, and thus highlights the hidden complexity of female vocalizations

Dawn song in superb fairy-wrens : a bird that seeks extrapair copulations during the dawn chorus

Functional explanations of the dawn chorus in birds remain elusive. One hypothesis suggests that this acoustic display may play a role in female choice of extrapair males. Most young in cooperatively breeding superb fairy-wrens, Malurus cyaneus, are sired by extra-group males. Females initiate extra-group copulations exclusively through predawn forays to males singing in the dawn chorus. We measured variation between males in dawn singing at three levels of song production: song components, structured into songs, which make up recitals. We related this variation to independent measures of male quality and social status. Males sing two distinct categories of songs during the dawn chorus: a complex and variable chatter song and a more repeatable trill song. Dominant males with male subordinate helpers produced chatter songs at a greater rate than either dominant males without helpers or subordinates, suggesting a role in the competition between male group members. However, the trill song is implicated in female choice because older males sing songs with a longer trill component and have greater extrapair success, and trade-offs between phrases within the trill component imply constraints on the length of the trill component in entirety that could enforce honesty. The dawn chorus of the superb fairy-wren may thus have a duel role, involving enforcement of dominance among male group members (male–male competition), and signalling attractiveness to mates (female choice)

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

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

Elaborate mimetic vocal displays by female Superb lyrebirds

Some of the most striking vocalizations in birds are made by males that incorporate vocal mimicry in their sexual displays. Mimetic vocalization in females is largely undescribed, but it is unclear whether this is because of a lack of selection for vocal mimicry in females, or whether the phenomenon has simply been overlooked. These issues are thrown into sharp relief in the superb lyrebird, Menura novaehollandiae, a basal oscine passerine with a lek-like mating system and female uniparental care. The spectacular mimetic song display produced by courting male lyrebirds is a textbook example of a sexually selected trait, but the vocalizations of female lyrebirds are largely unknown. Here, we provide the first analysis of the structure and context of the vocalizations of female lyrebirds. Female lyrebirds were completely silent during courtship; however, females regularly produced sophisticated vocal displays incorporating both lyrebird-specific vocalizations and imitations of sounds within their environment. The structure of female vocalizations varied significantly with context. While foraging, females mostly produced a complex lyrebird-specific song, whereas they gave lyrebird-specific alarm calls most often during nest defense. Within their vocal displays females also included a variety of mimetic vocalizations, including imitations of the calls of dangerous predators, and of alarm calls and song of harmless heterospecifics. Females gave more mimetic vocalizations during nest defense than while foraging, and the types of sounds they imitated varied between these contexts, suggesting that mimetic vocalizations have more than one function. These results are inconsistent with previous portrayals of vocalizations by female lyrebirds as rare, functionless by-products of sexual selection on males. Instead, our results support the hypotheses that complex female vocalizations play a role in nest defense and mediate female-female competition for breeding territories. In sum, this study reveals elaborate female vocal displays in a species widely depicted as an example of sexual selection for male extravagance, and thus highlights the hidden complexity of female vocalizations

Mimicry for all modalities

Mimicry is a canonical example of adaptive signal design. In principle, what constitutes mimicry is independent of the taxonomic identity of the mimic, the ecological context in which it operates, and the sensory modality through which it is expressed. However, in practice the study of mimicry is inconsistent across research fields, with theoretical and empirical advances often failing to cross taxonomic and sensory divides. We propose a novel conceptual framework whereby mimicry evolves if a receiver perceives the similarity between a mimic and a model and as a result confers a selective benefit onto the mimic. Here, misidentification and/or deception are no longer formal requirements, and mimicry can evolve irrespective of the underlying proximate mechanisms. The centrality of receiver perception in this framework enables us to formally distinguish mimicry from perceptual exploitation and integrate mimicry and multicomponent signalling theory for the first time. In addition, it resolves inconsistencies in our understanding of the role of learning in mimicry evolution, and shows that imperfect mimicry is expected to be the norm. Mimicry remains a key model for understanding signal evolution and cognition, and we recommend the adoption of a unified approach to stimulate future interdisciplinary developments in this fascinating area of research

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

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

How to be fed but not eaten : nestling responses to parental food calls and the sound of a predator's footsteps

Nestling birds could minimize the risk of being overheard by predators by becoming silent after parental alarm calls, begging only when parents arrive with food, and independently assessing cues that a predator is nearby. Begging only to parents is challenging because young that respond quickly can be more likely to be fed, so there is a benefit of using subtle cues of parental arrival, potentially leading to erroneous begging. Parents might reduce the risk of error by giving food calls signalling that they have arrived with food, but there have been few studies contrasting begging to food calls compared with other parental vocalizations. Furthermore, it is unknown whether nestlings can use acoustic cues to independently detect predators. White-browed scrubwren, Sericornis frontalis, nestlings become silent after parental alarm calls, but it is unknown whether they respond specifically to parental food calls or directly to predator sounds. We conducted a field playback experiment, and found that young begged more vigorously to food calls than other parental vocalizations tested, and nearly as strongly to playback as during real feeding visits by parents. However, nestlings also mistakenly begged to playback of superb fairy-wren, Malurus cyaneus, song, possibly because of acoustic similarities to food calls. Finally, nestlings responded with silence to playback of the sound of their major predator (pied currawong, Strepera graculina) walking on leaf litter. Scrubwren nestlings can therefore be ‘switched on’ and ‘switched off’ by parental vocalizations, are prone to error, and may independently assess risk

Destruction of a conspecific nest by a female Superb Lyrebird: Evidence for reproductive suppression in a bird with female-only parental care

2019 Copyright 2019 by Koninklijke Brill NV, Leiden, The Netherlands. Reproductive suppression, whereby individuals decrease the reproductive output of conspecific rivals, is well-studied in mammals, but while it is suspected to be widespread in birds, evidence of this phenomenon remains rare in this class. Here we provide compelling evidence of reproductive suppression in the Superb Lyrebird (Menura novaehollandie), with the first audio-visual documentation of the destruction of one female\u27s nest by another. We propose that nest destruction may be a strategy that females use in protracted territorial negotiations spanning multiple breeding seasons, and discuss how reproductive suppression could explain puzzling nesting behaviours in this species, such as the construction of multiple unfinished nests in each breeding season. More broadly, these results reveal high intra-sexual competition among female lyrebirds, and thus may provide an explanation for their elaborate vocal displays