Behavioral-psychological motivations encoded in the vocal repertoire of captive Amur tiger (Panthera tigris altaica) cubs

Background The Amur tiger (Panthera tigris altaica) is the largest and one of the most endangered cats in the world. In wild and captive cats, communication is mainly dependent on olfaction. However, vocal communication also plays a key role between mother and cubs during the breeding period. How cubs express their physiological and psychological needs to their mother and companions by using acoustic signals is little known and mainly hindered by the difficult process of data collection. Here, we quantitatively summarized the vocal repertoire and behavioral contexts of captive Amur tiger cubs. The aim of the present work was to investigate the behavioral motivations of cub calls by considering influential factors of age, sex, and rearing experiences. Results The 5335 high-quality calls from 65 tiger cubs were classified into nine call types (Ar-1, Ar-2, Er, eee, Chuff, Growl, Hiss, Haer, and Roar) produced in seven behavioral contexts. Except for Er, eight of the nine call types were context-specific, related to Play (Ar-2, eee, and Roar), Isolation (Ar-1), Offensive Context (Haer, Growl, and Hiss), and a friendly context (Chuff). Conclusions The results suggest that cubs are not quiet, but instead they express rich information by emitting various call types, which are probably crucial for survival in the wild. We herein provide the first detailed spectrogram classification to indicate vocal repertoires of calls and their coding with respect to behavioral contexts in Amur tiger cubs, and we pave the steps for revealing their social communication system, which can be applied for conservation of populations. These insights can help tiger managers or keepers to improve the rearing conditions by understanding the feline cubs’ inner status and needs by monitoring their vocal information expressions and exchanges.

The transition from the female-like great calls to male calls during ontogeny in southern yellow-cheeked gibbon males (Nomascus gabriellae)

It is well known that gibbons emit a pattern of vocalizations, which is specific for species and sex. A previous study showed, however, that immature southern yellow-cheeked gibbon (Nomascus gabriellae) males produce only female-like great calls from 2.3 to 5.3 years of age in co-singing interactions with their mothers. To date, nothing is known about how the vocal repertoire of a male changes from the female-like call (great call) to the male call (staccato notes and multi-modulation phrase) during vocal ontogeny. The goal of this study was to describe the transition from the female-like great call to the male call and the ontogeny of the male call. We predicted that the transition from the female-like great call to the male-specific call and the development of the male call is a normal part of the aging proces. If this is the case, the following phenomena will occur: (a) female vocalization should no longer be produced with the mature form of the multi-modulation phrase and (b) all stages of the male vocalization should occur gradually as the young male ages. Young males regularly emit both female-like great calls and male-specific calls between the ages of 5.6 to 7.1 years. Once the young males reached 7.1 years of age, they emitted male calls exclusively, and they continued to do so until the end of the observation period (at 8.11 years of age). It was confirmed that the young males emitted only female-like great calls during periods when they produced non-mature forms of a multi-modulation phrase (Fm0,1—none or one frequency modulation in second notes). Furhermore, the decrease in the number of female-like great calls was attributed to the development of the mature form of the multi-modulation phrase (Fm2—two or more frequency modulation in second notes), which developed with age. We also confirmed that the multi-modulation phrase developed gradually, while the development of the staccato notes occurred in leaps. A multi-modulation phrase developed as the initial part of the male-specific call. It was evolved from a simpler to a more complex form as the maximum frequency and age of the young males increased. Staccato notes subsequently developed in certain young males. Possible explanations for such vocal ontogeny in young males are discussed in this work.

Vocal repertoire, harmonic structure, and behavioural context in Red-throated Loon (Gavia stellata)

Among the five loon species (Gaviidae), Red-throated Loon (Gavia stellata) is the oldest lineage and is the most divergent in morphology and vocalizations. We substantially expand earlier description of calls for a nesting pair and non-breeding birds on Haida Gwaii, British Columbia, Canada. Three major calls used by the nesting pair (Quack, Wail, Plesiosaur) were all low frequency (700–3000 Hz) with multiple harmonics, calls that were also used by non-breeding birds without territories that overnight on freshwater lakes. Call duetting in the Wail and Plesiosaur, as well as sexually dimorphic frequencies and structure within the duets, typically occur in territorial display or pair interactions. The nesting pair used several calls audible only at short distances (Coo, Extended Coo, Staccato, Soft Raack) that were low frequency (200–1200 Hz), graded in behavioural intensity and that resulted in chick responses, including feeding or return to nest. A high amplitude Loud Raack was used by the female and is associated with flight incentives for pre-fledged chicks. Vocalizations of chicks, usually feeding solicitations to the adults, develop from simple chirps in the first week following hatch to more complex calls resembling the Wail and the Plesiosaur calls just prior to fledging. Although the majority of our acoustical descriptions are limited to a single nesting pair where sexes could be differentiated, these represent the first quantification of sound frequency, harmonic structure, and duration, most often associated with context-specific responses, and are suggestive of syntactical content to the vocal repertoire of this basal taxon.

The vocal development of the pale spear-nosed bat is dependent on auditory feedback

Human vocal development and speech learning require acoustic feedback, and humans who are born deaf do not acquire a normal adult speech capacity. Most other mammals display a largely innate vocal repertoire. Like humans, bats are thought to be one of the few taxa capable of vocal learning as they can acquire new vocalizations by modifying vocalizations according to auditory experiences. We investigated the effect of acoustic deafening on the vocal development of the pale spear-nosed bat. Three juvenile pale spear-nosed bats were deafened, and their vocal development was studied in comparison with an age-matched, hearing control group. The results show that during development the deafened bats increased their vocal activity, and their vocalizations were substantially altered, being much shorter, higher in pitch, and more aperiodic than the vocalizations of the control animals. The pale spear-nosed bat relies on auditory feedback for vocal development and, in the absence of auditory input, species-atypical vocalizations are acquired. This work serves as a basis for further research using the pale spear-nosed bat as a mammalian model for vocal learning, and contributes to comparative studies on hearing impairment across species. This article is part of the theme issue ‘Vocal learning in animals and humans’.

A small vocal repertoire during the breeding season expresses complex behavioral motivations and individual signature in the common coot

Background Although acoustic communication plays an essential role in the social interactions of Rallidae, our knowledge of how Rallidae encode diverse types of information using simple vocalizations is limited. We recorded and examined the vocalizations of a common coot (Fulica atra) population during the breeding season to test the hypotheses that 1) different call types can be emitted under different behavioral contexts, and 2) variation in the vocal structure of a single call type may be influenced both by behavioral motivations and individual signature. We measured a total of 61 recordings of 30 adults while noting the behavioral activities in which individuals were engaged. We compared several acoustic parameters of the same call type emitted under different behavioral activities to determine how frequency and temporal parameters changed depending on behavioral motivations and individual differences. Results We found that adult common coots had a small vocal repertoire, including 4 types of call, composed of a single syllable that was used during 9 types of behaviors. The 4 calls significantly differed in both frequency and temporal parameters and can be clearly distinguished by discriminant function analysis. Minimum frequency of fundamental frequency (F0min) and duration of syllable (T) contributed the most to acoustic divergence between calls. Call a was the most commonly used (in 8 of the 9 behaviors detected), and maximum frequency of fundamental frequency (F0max) and interval of syllables (TI) contributed the most to variation in call a. Duration of syllable (T) in a single call a can vary with different behavioral motivations after individual vocal signature being controlled. Conclusions These results demonstrate that several call types of a small repertoire, and a single call with function-related changes in the temporal parameter in common coots could potentially indicate various behavioral motivations and individual signature. This study advances our knowledge of how Rallidae use “simple” vocal systems to express diverse motivations and provides new models for future studies on the role of vocalization in avian communication and behavior.

Ukrainian vocal music of the 20th – early 21st century in the pedagogical repertoire of the soloist-vocalist

The purpose of the article. The paper describes the contemporary vocal pedagogical repertoire from the standpoint of its representativeness in relation to musical trends of the 20th – early 21st century. The methodology is based on a combination of historical, cultural, systemic, analytical, predictive methods, which made it possible to demonstrate the limited educational repertoire of vocalists, respectively, with didactic tasks and potential openness to expand its genre and style palette in connection with the need to train a universal academic singer. The scientific novelty of the paper lies in the fact that in Ukrainian science for the first time the problematic issues of the content of the pedagogical repertoire of academic vocalists in the context of the genre and style diversity of vocal music of the 20th – early 21st centuries were revealed. Conclusions. The contemporary pedagogical repertoire used in the preparation of academic vocalists does not reflect the stylistic and genre diversity of the musical art of the 20th – early 21st centuries, in particular, it does not contain avant-garde compositions, which have long been a constant of contemporary musical culture. Practical acquaintance with avant-garde classics is possible as part of an elective for those vocalists who plan to specialize in this direction of academic music, however, the pedagogical repertoire of training an academic vocalist does not provide for the performance of works of an avant-garde character and the acquisition of appropriate skills. The reasons for the inexpediency of including avant-garde music of the 20th – early 21st century in the main educational repertoire is the absence of a temporal distance, not always a high artistic level of contemporary works, the impossibility of including contemporary vocal music of an avant-garde character in the anthology due to the peculiarities of its notation and forms of existence, as well as the priority for the educational process of the classical vocal repertoire as such that forms the vocalist’s executive apparatus. At the same time, Ukrainian variety classics of the 20th century is an integral part of the educational repertoire of a contemporary academic vocalist, as it serves as a bridge between elite and popular musical culture.

Mastering the Aria through Song: Daron Hagen’s Amelia, “Apostrophe to the Stars,” and Selected Hagen Art Songs

Contemporary arias in English are too often excluded from student repertoire because they are perceived as being overly complex atonal works that are too challenging for the student. In order to counter this misconception, voice teachers should foster curiosity within students to seek repertoire with an open mind. Exploring music of living composers such as Daron Hagen can ignite student interest in contemporary art song and opera literature that expands the realms of what is thought to be traditional or appropriate vocal repertoire for students seeking a professional singing career.

Vocal repertoire and group-specific signature in the Smooth-billed Ani, Crotophaga ani Linnaeus, 1758 (Cuculiformes, Aves)

Vocal plasticity reflects the ability of animals to vary vocalizations according to context (vocal repertoire) as well as to develop vocal convergence (vocal group signature) in the interaction of members in social groups. This feature has been largely reported for oscine, psittacine and trochilid birds, but little has been investigated in birds that present innate vocalization. The smooth-billed ani (Crotophaga ani) is a social bird that lives in groups between two and twenty individuals, and which presents innate vocalization. Here we analyzed the vocal repertoire of this species during group activities, and further investigated the existence of a vocal group signature. The study was conducted in the Southeast of Brazil between May 2017 and April 2018. Two groups of smooth-billed anis were followed, Guararema and Charqueada groups, and their vocalizations were recorded and contextualized as to the performed behavior. The vocal repertoire was analyzed for its composition, context and acoustic variables. The acoustic parameters maximum peak frequency, maximum fundamental frequency, minimum frequency, maximum frequency and duration were analyzed. To verify the vocal signature of the group, we tested whether there was variation in the acoustic parameters between the monitored groups. We recorded ten vocalizations that constituted the vocal repertoire of the Smooth-billed Ani, five of which (“Ahnee”, “Whine”, “Pre-flight”, “Flight” and “Vigil”) were issued by the two groups and five exclusive to the Charqueada group. There were significant differences in the acoustic parameters for “Flight” and “Vigil” vocalizations between the groups, suggesting vocal group signature for these sounds. We established that the Smooth-billed Ani has a diverse vocal repertoire, with variations also occurring between groups of the same population. Moreover, we found evidence of vocal group signature in vocalizations used in the context of cohesion, defense and territory maintenance.