Quantifying Vocal Mimicry in the Greater Racket-Tailed Drongo: A Comparison of Automated Methods and Human Assessment

Agnihotri, Samira; Sundeep, P. V. D. S.; Seelamantula, Chandra Sekhar; Balakrishnan, Rohini

doi:10.1371/journal.pone.0089540

Cited by 8 publications

(6 citation statements)

References 26 publications

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“…For example, it has been difficult to account for vocal mimicry that does not function deceptively (Dobkin, 1979;Starrett, 1993), although such mimicry appears common amongst oscine passerines (Baylis, 1982). Furthermore, vocal mimicry has sometimes been assumed to be-or defined as-a learnt trait (Dobkin, 1979;Baylis, 1982;Pasteur, 1982;Kelley et al, 2008) but not always (Rowe et al, 1986), and the role of mimetic accuracy in the classification of vocal mimicry has been ambiguous (Baylis, 1982;Hamao & Eda-Fujiwara, 2004;Dalziell & Magrath, 2012;Igic & Magrath, 2013;Agnihotri et al, 2014). Our definition of mimicry encompasses both deceptive and non-deceptive mimetic signals and does not depend on mechanisms of acquisition.…”

Section: Discussionmentioning

confidence: 99%

Avian vocal mimicry: a unified conceptual framework

et al. 2014

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Mimicry is a classical example of adaptive signal design. Here, we review the current state of research into vocal mimicry in birds. Avian vocal mimicry is a conspicuous and often spectacular form of animal communication, occurring in many distantly related species. However, the proximate and ultimate causes of vocal mimicry are poorly understood. In the first part of this review, we argue that progress has been impeded by conceptual confusion over what constitutes vocal mimicry. We propose a modified version of Vane-Wright's (1980) widely used definition of mimicry. According to our definition, a vocalisation is mimetic if the behaviour of the receiver changes after perceiving the acoustic resemblance between the mimic and the model, and the behavioural change confers a selective advantage on the mimic. Mimicry is therefore specifically a functional concept where the resemblance between heterospecific sounds is a target of selection. It is distinct from other forms of vocal resemblance including those that are the result of chance or common ancestry, and those that have emerged as a by-product of other processes such as ecological convergence and selection for large song-type repertoires. Thus, our definition provides a general and functionally coherent framework for determining what constitutes vocal mimicry, and takes account of the diversity of vocalisations that incorporate heterospecific sounds. In the second part we assess and revise hypotheses for the evolution of avian vocal mimicry in the light of our new definition. Most of the current evidence is anecdotal, but the diverse contexts and acoustic structures of putative vocal mimicry suggest that mimicry has multiple functions across and within species. There is strong experimental evidence that vocal mimicry can be deceptive, and can facilitate parasitic interactions. There is also increasing support for the use of vocal mimicry in predator defence, although the mechanisms are unclear. Less progress has been made in explaining why many birds incorporate heterospecific sounds into their sexual displays, and in determining whether these vocalisations are functionally mimetic or by-products of sexual selection for other traits such as repertoire size. Overall, this discussion reveals a more central role for vocal mimicry in the behavioural ecology of birds than has previously been appreciated. The final part of this review identifies important areas for future research. Detailed empirical data are needed on individual species, including on the structure of mimetic signals, the contexts in which mimicry is produced, how mimicry is acquired, and the ecological relationships between mimic, model and receiver. At present, there is little information and no consensus about the various costs of vocal mimicry for the protagonists in the mimicry complex. The diversity and complexity of vocal mimicry in birds raises important questions for the study of animal communication and challenges our view of the nature of mimicry itself. Therefore, a better understanding of...

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Section: Discussionmentioning

confidence: 99%

Avian vocal mimicry: a unified conceptual framework

et al. 2014

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“…We believe therefore that the putative call is likely to be mimicry of a Jerdon's courser call by a bay-backed shrike, a known mimic (Yosef et al, 2020). Mimics can often sound similar to the model in acoustic characteristics, and are difficult to discern without context (Agnihotri et al, 2014). In the absence of additional recordings, it is difficult to assess definitively whether the detected call was of Jerdon's courser or of a mimic.…”

Section: Discussionmentioning

confidence: 99%

Species detection framework using automated recording units: a case study of the Critically Endangered Jerdon's courser

Arvind

Joshi

Charif

et al. 2022

Oryx

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With the advent of automated recording units, bioacoustic monitoring has become a popular tool for the collection of long-term data across extensive landscapes. Such methods involve two main components: hardware for audio data acquisition and software for analysis. In the acoustic monitoring of threatened species, a species-specific framework is often essential. Jerdon's courser Rhinoptilus bitorquatus is a Critically Endangered nocturnal bird endemic to a small region of the Eastern Ghats of India, last reported in 2008. Here we describe a reproducible and scalable acoustic detection framework for the species, comparing several commonly available hardware and detection methods and using existing software. We tested this protocol by collecting 24,349 h of data during 5 months. We analysed the data with two commercially available sound analysis programmes, following an analysis pipeline created for this species. Although we did not detect vocalizations of Jerdon's courser, this study provides a framework using a combination of hardware and software for future research that other conservation practitioners can implement. Vocal mimicry can aid or confound in detection and we highlight the potential role of mimicry in the detection of such threatened species. This species-specific acoustic detection framework can be scaled and tailored to monitor other species.

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“…As a highly biodiverse tropical country, the example of India serves to illustrate the global promise of community bioacoustics, and the need for more studies utilizing these methods. There are still relatively few passive acoustic studies in India Buxton et al, 2018a;Krishnan, 2019a;Lahiri et al, 2021), and most acoustic sampling relies on call counts or focal recordings (Khaling et al, 1998;Agnihotri et al, 2014;Purushotham and Robin, 2016). For lesser-known Indian taxa such as bats, comprehensive call libraries are few (Raghuram et al, 2014;Wordley et al, 2018;Chakravarty et al, 2020).…”

Section: Synthesis: Community Bioacoustics In Long-term Biodiversity Monitoring and Conservationmentioning

confidence: 99%

Community Bioacoustics: Studying Acoustic Community Structure for Ecological and Conservation Insights

et al. 2021

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The diversity of animal acoustic signals has evolved due to multiple ecological processes, both biotic and abiotic. At the level of communities of signaling animals, these processes may lead to diverse outcomes, including partitioning of acoustic signals along multiple axes (divergent signal parameters, signaling locations, and timing). Acoustic data provides information on the organization, diversity and dynamics of an acoustic community, and thus enables study of ecological change and turnover in a non-intrusive way. In this review, we lay out how community bioacoustics (the study of acoustic community structure and dynamics), has value in ecological monitoring and conservation of diverse landscapes and taxa. First, we review the concepts of signal space, signal partitioning and their effects on the structure of acoustic communities. Next, we highlight how spatiotemporal ecological change is reflected in acoustic community structure, and the potential this presents in monitoring and conservation. As passive acoustic monitoring gains popularity worldwide, we propose that the analytical framework of community bioacoustics has promise in studying the response of entire suites of species (from insects to large whales) to rapid anthropogenic change.

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Quantifying Vocal Mimicry in the Greater Racket-Tailed Drongo: A Comparison of Automated Methods and Human Assessment

Cited by 8 publications

References 26 publications

Avian vocal mimicry: a unified conceptual framework

Avian vocal mimicry: a unified conceptual framework

Species detection framework using automated recording units: a case study of the Critically Endangered Jerdon's courser

Community Bioacoustics: Studying Acoustic Community Structure for Ecological and Conservation Insights

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