Large Vocal Repertoire Research Articles

Reservoirs of pestilence: what pathogen and rodent community analyses can tell us about transmission risk

A recommendation of: Samantha Bowser, Maggie MacPherson A study on the role of social information sharing leading to range expansion in songbirds with large vocal repertoires: Enhancing our understanding of the Great-Tailed Grackle (Quiscalus mexicanus) alarm call https://doi.org/10.17605/OSF.IO/2UFJ5

Vocal repertoire of Azure-winged Magpies (Cyanopica cyanus): A context-associated communication system

Signals within animals’ vocal communication are considered functional referential and context-specific. Even in the absence of the context, receivers are expected to acquire the information of calls and respond specifically. Whereas the framework was supported by plenty of evidence, its exhaustivity in describing all animal vocalisations has been questioned. Here, we investigated the vocal repertoire of a cooperatively breeding species, Azure-winged Magpie (Cyanopica cyanus), to present evidence for referential signals. The results showed that Azure-winged Magpies had a relatively large vocal repertoire, consisting of twelve distinct calls. These calls were associated with the context including movement, begging for food, contact, vigilance against predators, etc. However, even the predator-specific alarm calls would induce various responses of receivers. This implies that multiple pieces of information are involved in the vocalisation, which could be utilised by the receiver to select an appropriate response based on the surroundings. Our study gives a detailed description of the context and function of the vocal repertoire in Azure-winged Magpies, laying the foundation for further investigation on the developmental mechanisms of bird vocalisations. This study also suggests that the referential signals of animal vocalisations may not be limited to the context-specific responses of receivers and need to be discussed from a broader perspective.

A convergent interaction engine: vocal communication among marmoset monkeys.

To understand the primate origins of the human interaction engine, it is worthwhile to focus not only on great apes but also on callitrichid monkeys (marmosets and tamarins). Like humans, but unlike great apes, callitrichids are cooperative breeders, and thus habitually engage in coordinated joint actions, for instance when an infant is handed over from one group member to another. We first explore the hypothesis that these habitual cooperative interactions, the marmoset interactional ethology, are supported by the same key elements as found in the human interaction engine: mutual gaze (during joint action), turn-taking, volubility, as well as group-wide prosociality and trust. Marmosets show clear evidence of these features. We next examine the prediction that, if such an interaction engine can indeed give rise to more flexible communication, callitrichids may also possess elaborate communicative skills. A review of marmoset vocal communication confirms unusual abilities in these small primates: high volubility and large vocal repertoires, vocal learning and babbling in immatures, and voluntary usage and control. We end by discussing how the adoption of cooperative breeding during human evolution may have catalysed language evolution by adding these convergent consequences to the great ape-like cognitive system of our hominin ancestors. This article is part of the theme issue 'Revisiting the human 'interaction engine': comparative approaches to social action coordination'.

Acoustic differentiation and classification of wild belugas and narwhals using echolocation clicks

Belugas (Delphinapterus leucas) and narwhals (Monodon monoceros) are highly social Arctic toothed whales with large vocal repertoires and similar acoustic profiles. Passive Acoustic Monitoring (PAM) that uses multiple hydrophones over large spatiotemporal scales has been a primary method to study their populations, particularly in response to rapid climate change and increasing underwater noise. This study marks the first acoustic comparison between wild belugas and narwhals from the same location and reveals that they can be acoustically differentiated and classified solely by echolocation clicks. Acoustic recordings were made in the pack ice of Baffin Bay, West Greenland, during 2013. Multivariate analyses and Random Forests classification models were applied to eighty-one single-species acoustic events comprised of numerous echolocation clicks. Results demonstrate a significant difference between species’ acoustic parameters where beluga echolocation was distinguished by higher frequency content, evidenced by higher peak frequencies, center frequencies, and frequency minimums and maximums. Spectral peaks, troughs, and center frequencies for beluga clicks were generally > 60 kHz and narwhal clicks < 60 kHz with overlap between 40–60 kHz. Classification model predictive performance was strong with an overall correct classification rate of 97.5% for the best model. The most important predictors for species assignment were defined by peaks and notches in frequency spectra. Our results provide strong support for the use of echolocation in PAM efforts to differentiate belugas and narwhals acoustically.

Acoustic differentiation and classification of wild belugas and narwhals using echolocation clicks

Belugas (Delphinapterus leucas) and narwhals (Monodon monoceros) are highly social toothed Arctic cetaceans with large vocal repertoires and similar acoustic profiles. Passive Acoustic Monitoring (PAM) that uses multiple hydrophones over large spatiotemporal scales has been the primary method to study their populations, particularly in response to rapid climate change and increasing underwater noise. This study marks the first acoustic comparison between wild belugas and narwhals from the same location and reveals that they can be acoustically differentiated and classified solely by echolocation clicks. Acoustic recordings were made in the pack ice of Baffin Bay, West Greenland during 2013. Multivariate analyses and Random Forests classification models were applied to eighty-one single-species acoustic events comprised of numerous echolocation clicks. Results demonstrate a significant difference between species’ acoustic parameters where beluga echolocation was distinguished by higher frequency content. Classification model predictive performance was strong with an overall correct classification rate of 97.5% for the best model. The most important predictors for species assignment were defined by peaks and notches in frequency spectra. Our results provide strong support for the use of echolocation in PAM efforts to differentiate belugas and narwhals.

Agonistic vocalization behaviour in the male ring-tailed lemur (Lemur catta).

Vocalizations are used by group-living animals as aggressive and submissive signals during agonistic interactions, and are also used to maintain dominance hierarchies in many species. For gregarious strepsirrhines with large vocal repertoires and differentiated dominance ranks like the ring-tailed lemur (Lemur catta), agonistic vocalization use is important to study to better understand their social adaptations.To determine whether ring-tailed lemur vocalizations such as the yip, cackle, twitter, chutter, and plosive bark were used as aggressive or submissive signals during agonism and uttered at different rates by males of differing dominance ranks and ages, 565 h of focal data were collected on 31 individual males aged ≥ 1 year from Beza Mahafaly Special Reserve, Madagascar. Yip, cackle, and twitter vocalizations were consistently used during agonistic submissive interactions with both males and females, chutter vocalizations were used during aggressive agonistic interactions with males and submissive agonistic interactions with males and females, and plosive bark vocalizations were used across behavioural contexts but not particularly during agonism. Males of all ages employed all vocalizations, and while low-ranking males uttered yip calls at higher rates, males of all dominance ranks uttered cackle, twitter, chutter, and plosive bark vocalizations. These results advance our knowledge of how male lemurs utilize agonistic vocalizations to maintain inter-individual relationships with males and females, and improve our overall understanding of the function of different agonistic vocalizations in wild lemurs.

Pup Directed Vocalizations of Adult Females and Males in a Vocal Learning Bat

Social feedback plays an important role in human language development and in the vocal ontogeny of non-human animals. A special form of vocal feedback in humans, infant-directed speech – or motherese –facilitates language learning and is socially beneficial by increasing attention and arousal in the child. It is characterized by high pitch, expanded intonation contours and slower speech tempo. Furthermore, the vocal timbre (i.e. ’color’ of voice) of motherese differs from the timbre of adult-directed speech. In animals, pup-directed vocalizations are very common, especially in females. But so far there is hardly any research on whether there is a similar phenomenon as motherese in animal vocalizations. The greater sac-winged bat, Saccopteryx bilineata, is a vocal production learner with a large vocal repertoire that is acquired during ontogeny. We compared acoustic features between female pup-directed and adult-directed vocalizations and demonstrated that they differed in timbre and peak frequency. Furthermore, we described pup-directed vocalizations of adult males. During the ontogenetic period when pups’ isolation calls (used to solicit maternal care) are converging towards each other to form a group signature, adult males also produce isolation calls. Pups’ isolation calls are acoustically more similar to those of males from the same social group than to other males. In conclusion, our novel findings indicate that parent-offspring communication in bats is more complex and multifaceted than previously thought, with female pup-directed vocalizations reminiscent of human motherese and male pup-directed vocalizations that may facilitate the transmission of a vocal signature across generations.

Affiliative Contact Calls during Group Travel: Chirp and Wail Vocalization Use in the Male Ring-Tailed Lemur (Lemur catta)

Affiliative vocalizations occur across primate taxa and may be used to maintain spatial cohesion and/or to regulate social interactions in group-living species. For gregarious strepsirhines like the ring-tailed lemur (Lemur catta), with large vocal repertoires and several distinct affiliative vocalizations including the chirp and wail, it is important to understand behavioural usage of these vocalizations to gain insight into their social interactions. To determine whether chirp and wail vocalizations facilitate group cohesion, regulate interactions to achieve socially positive outcomes, and are correlated with differences in individual characteristics such as dominance rank and age, I collected 565 h of focal data on 31 males aged ≥1 year at Beza Mahafaly Special Reserve, Madagascar, from March to July 2010. I found that chirp and wail vocalizations occurred at the highest rates during group-wide travel compared to other behaviours. Although nearest neighbour distance did not influence calling rate, focal animals maintained the same distance or were located closer to nearest neighbours after calling. Both chirp and wail calls were heard in behavioural contexts without agonism rather than agonistic contexts. No relationship was found between male calling rate and dominance rank or age, although the chirp showed a non-significant tendency to be produced at higher rates by younger males. Overall, my results indicated that ring-tailed lemur males of all ages and dominance ranks used both chirp and wail vocalizations as contact calls during group-wide travel events, helping individuals maintain proximity to other group members during movement. Chirp and wail vocalizations may additionally help regulate the caller’s social interactions and promote increased tolerance from conspecifics. These findings add to our understanding of the breadth of communication behaviour in wild lemurs, thus furthering our knowledge of the social lives and cognitive abilities of strepsirhines. Through examining the complexity of vocalization use by a living lemur species with a communication system much like early social primates, we gain broad insight into the evolution of primate sociality.

Vocal Repertoire and Intraspecific Variation within Two Loud Calls of the Small-Eared Greater Galago (Otolemur garnettii) in Tanzania and Kenya

Vocal repertoires and call structure can provide insights into the behaviour and evolution of species, as well as aid in taxonomic classification. Nocturnal primates have large vocal repertoires. This suggests that acoustic communication plays an important role in their life histories. Little is known about the behavioural context or the intraspecific variation of their vocalisations. We used autonomous recording units and manual recorders to investigate the vocal behaviour and structure of loud calls of the small-eared greater galago (Otolemur garnettii)in Kenya and Tanzania. We describe the vocal repertoire, temporal calling patterns and structure of 2 loud calls of 2 subspecies: O. g. panganiensis and O. g. kikuyuensis. We found considerable intraspecific structural differences in both loud calls. These are congruent with the current subspecies classification. Differences in vocalisations among populations are not consistent with the “acoustic adaptation hypothesis,” rather they are likely a result of geographic variation due to isolation caused by vegetational barriers in southern Kenya.

Song and aggressive signaling in Bachman's Sparrow

ABSTRACT Male Bachman's Sparrows (Peucaea aestivalis) have large vocal repertoires containing many song types and multiple categories of songs and calls. We examined the territorial defense function of the vocal repertoire of male Bachman's Sparrows by quantifying singing behaviors and aggressiveness in response to a simulated territorial intrusion. We compared vocal and other behaviors between the intrusion and post-intrusion periods, compared more aggressive males (attackers) with less aggressive males (non-attackers), and tested for signals that predict attack. During intrusion, subjects switched among their song types at higher rates, however, song switching did not differ between more and less aggressive males. More aggressive males sang more low-amplitude “whisper songs.” In line with previous studies of aggressive signaling in songbirds, Bachman's Sparrows appear to use low-amplitude song to threaten rivals. The eavesdropping avoidance hypothesis predicts that low-amplitude songs should have acoust...

Accounting for syntax in analyses of countersinging reveals hidden vocal dynamics in a songbird with a large repertoire

Identifying the signalling strategies employed by animals during vocal interactions is a challenge, especially for species with large vocal repertoires. We propose that efforts to study such vocal dynamics can benefit by integrating models of syntax into their analyses. In this study, we conducted playback experiments on Cassin's vireo, Vireo cassinii, to examine the role of syntax, and more specifically, shared syntactic patterns, in countersinging. We presented 11 males with song sequences ordered according to population norms, and with sequences whose order deviated from population norms. We did not find evidence that individuals markedly altered their responses based on the syntax of the playback, either in their physical approach to the speaker or in the quantity of song they delivered in response. We did, however, find evidence that syntax was important in governing their choice of phrase types in response to the playbacks. Subjects did not match the playback phrase types. Instead, they engaged in a vocal behaviour referred to as song advancing, where they responded to a stimulus phrase type by singing the phrase type that most often followed the stimulus in their own normal song sequences. When playback sequences were ordered according to population norms, song advancing resulted in birds pre-empting the upcoming playback phrase type or delivering another of the prior playback phrase types (i.e. delayed matching) at higher rates than when playback sequences deviated from population norms. The detection of song advancing was only possible with the explicit inclusion of syntax in our analysis, suggesting that studies of the vocal interactions of species with repertoires of multiple vocalizations can benefit from consideration not only of a subject's repertoire, but also their syntax.

The complex acoustic repertoire of a highly social species, the Noisy Miner, Manorina melanocephala

ABSTRACTCommunication is an essential component of social interactions between individuals, particularly in larger group sizes. To gain further insight into the factors that underpin cooperative behaviour, herein we examine the acoustic repertoire of the Noisy Miner, Manorina melanocephala, a cooperative species that lives in large colonies. To determine the structure and composition of the Noisy Miner repertoire, we measured the call rates and major acoustic parameters of common vocalisations from colour-banded individuals located at two discrete colonies. A total of 13 different vocalisation types were identified, of which 3 are newly described, with an additional 10 vocalisations being quantified in a new social context. Importantly, we describe a call given only by females and document both sexes producing some calls that were previously thought to be sex-specific. The putative repertoire identified was supported by statistical assessments confirming differences in their spectral and temporal features. Vocalisations were given across a range of social contexts, including the mobbing of predators, aerial alarm vocalisations, apparent maintenance of group cohesion and advertisement of individual location and/or status. This study quantifies the rich vocal repertoire of this social species, and provides further implications for the link between cooperative breeding and large vocal repertoires.

Large vocal repertoires do not constrain the dear enemy effect: a playback experiment and comparative study of songbirds

Many territorial animals are less aggressive towards neighbours than they are towards strangers. This phenomenon is known as the ‘dear enemy’ effect and it occurs because strangers represent a considerably higher threat to territory take-over compared to neighbours. Some evidence has suggested that large repertoires may constrain neighbour–stranger discrimination. We tested whether songbirds with large repertoires exhibit neighbour–stranger discrimination, conducting a playback study on a songbird with a large vocal repertoire, and a comparative analysis of the dear enemy effect across all published studies of songbirds. In our playback study, we broadcast neighbour and stranger songs within the breeding territories of red-eyed vireos, Vireo olivaceus, a songbird species with a large song repertoire (ca. 50 songs per individual). Vireos responded significantly more aggressively to playback of stranger versus neighbour songs; subjects approached closer to the loudspeaker, had a lower latency to approach the loudspeaker, spent more time near the loudspeaker and sang more soft songs during stranger trials than during neighbour trials. We examined song sharing between red-eyed vireos and found low levels of song sharing between neighbours, suggesting that red-eyed vireos may discriminate among conspecifics based on individually distinctive song types. We then conducted a comparative analysis of neighbour–stranger discrimination across the published literature on songbirds, using a phylogenetically controlled analysis to explore whether species with large repertoires are less likely to discriminate between neighbours and strangers. Across 34 species, we found no evidence that songbirds with large repertoires are constrained in their ability to distinguish between neighbours and strangers. We conclude that large song repertoires do not inhibit neighbour–stranger discrimination in red-eyed vireos specifically, or songbirds generally.

Geographic variation in the vocalizations of Australian palm cockatoos (Probosciger aterrimus)

Vocal dialects have been well studied in songbirds, but there have been fewer examples from parrots. The Australian population of palm cockatoos (Probosciger aterrimus aterrimus) from Cape York Peninsula in far north Queensland has an unusually large vocal repertoire for a parrot. Most calls are made during their unique display ritual, which also includes a variety of postures, gestures and the use of a manufactured sound tool. Here, we quantify the geographic structural variation of contact calls within and between six major populations of palm cockatoos in Australia, as well as the extent to which frequently given call types are shared. We found that palm cockatoos from the east coast (Iron Range National Park) possess unique contact calls and have fewer call types in common with other locations. This may have resulted from their long-term isolation in rainforest habitat refugia. Such variety in vocal traits presents a rare opportunity to investigate the evolutionary forces creating behavioural diversity in wild parrots. This is also a step towards assessing links between behavioural variation and population connectivity, which is important information for determining the conservation status of palm cockatoos.

Vocal complexity in the palm cockatoo (Probosciger aterrimus)

Parrots are renowned for their capacity for vocal learning and production of diverse sounds in captivity, yet little is known about why such advanced vocal capabilities have evolved. Here, we provide a detailed description and statistical classification of the vocal repertoire of wild palm cockatoos Probosciger aterrimus and investigate the behavioural contexts of vocalizations. We show that palm cockatoos produce vocalizations that conform to most of the common vocalizations described for wild parrots, but also produce a variety of additional syllables in a phonological syntactic manner in the contexts of display and vocal-exchange with neighbouring individuals. These additional syllables are mainly produced by males and are often combined to form long, complex sequences. Unlike most parrots, palm cockatoos defend large multipurpose territories and we speculate that the large vocal repertoire and vocal assemblages of palm cockatoos may function in territorial defense.

Vocal repertoire of cooperatively breeding Smooth-billed Anis

Calls are functionally diverse signals that mediate behavior in a wide variety of contexts in both passerines and non-passerines. However, the call-based acoustic communication systems of non-passerines have received less attention from investigators than those of passerines. We examined the vocal repertoire of Smooth-billed Anis (Crotophaga ani), cooperatively breeding cuckoos that live in groups with multiple breeding pairs. We recorded calls from 22 groups over two breeding seasons at the Cabo Rojo National Wildlife Refuge in Puerto Rico. We identified 11 call types and one group vocalization, and used an automated sound measurement program to quantify their acoustic features. Discriminant function analysis (DFA) correctly classified 74.2% of calls based on these features. The vocal repertoire of Smooth-billed Anis is larger than that reported for the three other species in the subfamily Crotophaginae. Smooth-billed Anis have at least two alarm calls, two nest-specific calls, and one nest defense call. We also identified one possible signal of aggressive intent, one possible appeasement signal, and two calls that may communicate identity. The relatively large vocal repertoire of Smooth-billed Anis and association of distinct call types with different functions and contexts supports the main prediction of the social complexity hypothesis, i.e., species with more complex social systems will have more complex communication systems.

Functional morphology of the Alligator mississippiensis larynx with implications for vocal production.

Sauropsid vocalization is mediated by the syrinx in birds and the larynx in extant reptiles; but whereas avian vocal production has received much attention, the vocal mechanism of basal reptilians is poorly understood. The American alligator (Alligator mississippiensis) displays a large vocal repertoire during mating and in parent-offspring interactions. Although vocal outputs of these behaviors have received some attention, the underlying mechanism of sound production remains speculative. Here, we investigate the laryngeal anatomy of juvenile and adult animals by macroscopic and histological methods. Observations of the cartilaginous framework and associated muscles largely corroborate earlier findings, but one muscle, the cricoarytenoideus, exhibits a heretofore unknown extrinsic insertion that has important implications for effective regulation of vocal fold length and tension. Histological investigation of the larynx revealed a layered vocal fold morphology. The thick lamina propria consists of non-homogenous extracellular matrix containing collagen fibers that are tightly packed below the epithelium but loosely organized deep inside the vocal fold. We found few elastic fibers but comparatively high proportions of hyaluronan. Similar organizational complexity is also seen in mammalian vocal folds and the labia of the avian syrinx: convergent morphologies that suggest analogous mechanisms for sound production. In tensile tests, alligator vocal folds demonstrated a linear stress-strain behavior in the low strain region and nonlinear stress responses at strains larger than 15%, which is similar to mammalian vocal fold tissue. We have integrated morphological and physiological data in a two-mass vocal fold model, providing a systematic description of the possible acoustic space that could be available to an alligator larynx. Mapping actual call production onto possible acoustic space validates the model's predictions.

How a songbird with a continuous singing style modulates its song when territorially challenged.

In songbirds of the temperate zone, often only males sing and their songs serve to attract females and to deter territorial rivals. In many species, males vary certain aspects of their singing behavior when engaged in territorial interactions. Such variation may be an honest signal of the traits of the signaler, such as fighting strength, condition, or aggressive motivation, and may be used by receivers in decisions on whether to retreat or to escalate a fight. This has been studied intensively in species that sing discontinuously, in which songs are alternating with silent pauses. We studied contextual variation in the song of skylarks (Alauda arvensis), a songbird with a large vocal repertoire and a continuous and versatile singing style. We exposed subjects to simulated territorial intrusions by broadcasting conspecific song and recorded their vocal responses. We found that males sing differently if they are singing spontaneously with no other conspecific around than if they are territorially challenged. In this last case, males produced lower-frequency syllables. Furthermore, they increased the sound density of their song: they increased the proportion of sound within song. They seem to do so by singing different elements of their repertoire when singing reactively. Furthermore, they increased the consistency of mean peak frequency: they repeated syllable types with less variability when singing reactively. Such contextual variation suggests that skylarks might use low frequencies, sound density, and song consistency to indicate their competitive potential, and thus, those song features might be important for mutual assessment of competitive abilities.

The alarm call system of wild black-fronted titi monkeys, Callicebus nigrifrons

Upon encountering predators, many animals produce specific vocalisations that alert others and sometimes dissuade the predators from hunting. Callicebus monkeys are known for their large vocal repertoire, but little is known about the function and meaning of most call types. We recorded a large number of natural predator responses from five different groups of black-fronted titi monkeys in their Atlantic forest habitat in South Eastern Brazil. When detecting predatory threats, adult group members responded with call sequences that initially consisted of two brief, high-pitched calls with distinct frequency contours. Call A was mainly given to raptors but also to predatory capuchin monkeys and other threats within the canopy, while call B was given to predatory or non-predatory disturbances on the ground. In later parts of the sequences, we also recorded a high-pitched unmodulated call C and various low-pitched loud calls. Results therefore suggest that calls A and B provide listeners with rapid and reliable information about the general classes of danger experienced by the caller, while obtaining more specific information through other call types and combinations and behavioural responses. We discuss these findings in relation to current evolutionary theory of primate communication.

Neighbor–Stranger Discrimination in Concave‐Eared Torrent Frogs, Odorrana tormota

AbstractThe dear enemy phenomenon in which animals discriminate familiar neighbors from unknown strangers, and respond more aggressively to strangers is well established in various social animals, especially in songbirds and mammals. So far, very few studies of neighbor–stranger discrimination have been carried out in amphibians and the results have been mixed. Thus, it is unclear whether this phenomenon exists commonly in frogs and toads, and whether it is exhibited by species with large vocal repertoires. We conducted acoustic playback experiments with male concave‐eared torrent frogs (Odorrana tormota, a species with an unusually large vocal repertoire) kept in a tank in a quiet room to investigate whether or not they can discriminate strangers from neighbors acoustically. Nine of the 14 males tested showed evoked vocal responses to the calls from strangers, but none to calls from neighbors; vocal response to the calls from strangers was accompanied by aggressive motor activity. These results demonstrate that male O. tormota possess the ability to discriminate neighbors from strangers acoustically. Odorrana tormota therefore joins three ranid species (Rana catesbiana, Rana clamitans, Rana dalmatina, all known to have a comparatively small and stereotyped vocal repertoires) as the only anurans demonstrated to have this ability. Given the difference in signaling complexity between these frog species, the salient acoustic features used for discriminating neighbors and strangers are likely to be quite distinct.