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Killer whale vocal behaviour is intricately connected to dietary preferences. In Iceland, killer whales feeding on herring are vocally active, use tail slaps to debilitate fish and produce herding calls, thought to function to affect prey. However, there is still limited understanding of how sounds are used by the whales or produced during feeding activities. We used acoustic data collected using archival tags deployed in 2009 (n = 4), 2021 (n = 9), 2022 (n = 5) and 2023 (n = 8) to investigate killer whale sound production during feeding on herring. The acoustic record was divided into 5-min bins, and the presence of clicks and tail slaps was marked for each bin. Then, sound production in the 5-min prior and 1-min following each tail slap was examined in detail, marking echolocation clicks, buzzes, herding calls and prey consumption sounds. Most bins including echolocation clicks (81.8%) were found to either contain a tail slap or to immediately precede a tail slap, indicating that echolocation is primarily used during feeding and likely less so for navigation and orientation. Buzzes, which likely function to locate debilitated prey in the immediate vicinity of the whale, followed 73.5% of the tail slaps. Prey consumption sounds might be useful as markers of feeding success and were present in 63% of feeding events, always following buzzes. Herding calls were found in 26% of feeding events in 2021–2023 and absent in 2009, which may suggest that it is a group-specific call or that it is not used in all feeding events. Variations in sound production of herring-eating killer whales during feeding may be driven by environmental characteristics, individual identity or prey characteristics; future studies combining sound with other tag sensor data such as video, and prey sampling will be crucial to explore these possible drivers. [ABSTRACT FROM AUTHOR]

Monitoring vulnerable species inhabiting mountain environments is crucial to track population trends and prioritize conservation efforts. However, the challenging nature of these remote areas poses difficulties in implementing effective and consistent monitoring programmes. To address these challenges, we examined the potential of passive acoustic monitoring of a cryptic high mountain bird species, the Rock Ptarmigan Lagopus muta. For 5 months in each of two consecutive years, we deployed 38 autonomous recording units in 10 areas of the Swiss Alps where the species is monitored by a national count monitoring programme. Once the recordings were collected, we built a machine‐learning algorithm to automate call recognition. We focused on studying the species' daily and seasonal calling phenology and relating these to meteorological and climatic data. Rock Ptarmigans were vocally active from March to July, with a peak of activity occurring between mid‐March and late April, 1 or 2 months earlier than the second half of May when the counts of the monitoring programme take place. The calling rate peaked at dawn before dropping rapidly until sunrise. Daily vocal activity demonstrated a consistent association with weather conditions and moon phase, whereas the timing of seasonal vocal activity varied with temperature and snow conditions. We found that the peak of vocal activity occurred when the snowpack was still thick and snow cover was close to 100% but with a local peak of high temperatures. Between our two study years, the peak of vocal activity occurred 30 days later in the colder year, suggesting phenological plasticity in relation to environmental conditions. Passive acoustic monitoring has the potential to complement conventional acoustic counts of cryptic birds by highlighting periods of higher detectability of individuals, and to survey small populations that often remain undetected during single visits. Moreover, our study supports the idea that passive acoustic monitoring can provide valuable data over large spatial and temporal scales, allowing decryption of hidden ecological patterns and assisting in conservation efforts. [ABSTRACT FROM AUTHOR]

Diverse information encoding systems, including human language, the vocal and gestural systems of non-human animals and the structure of DNA and proteins, have been found to conform to ‘Menzerath’s Law’—a negative relationship between the number of units composing a sequence, and the size of those units. Here, we test for the presence of Menzerath’s Law in the vocal bouts produced in a submissive context by meerkats (Suricata suricatta). Using a suite of Bayesian mixed effects models, we examined 1676 vocal bouts produced by 89 wild meerkats, ranging from 1 to 590 calls in length, to determine whether the number of calls composing each bout had a negative relationship with the duration of those calls or their inter-call intervals. In contradiction to Menzerath’s Law, we found that the duration of vocalizations had a positive relationship with the number of calls in a bout. However, the duration of intervals between calls did have a negative relationship with bout size. Moreover, both calls and intervals had longer durations the closer they were positioned to the end of the bout. These findings highlight the multi-faceted ways in which efficiency trade-offs can occur in the vocal repertoires of non-human animals, shaping variability in the production of signal forms.

The grey heron is an extensively studied and widely distributed colonial bird species in the Old World; however, relevant information on the role played by vocalisations during the life cycle of individuals is still lacking. This research aimed to deepen the available knowledge on the repertoire and vocal behaviour of adults during the breeding season, through a bioacoustic approach and choosing as study areas two heronries in different environmental contexts. Colonies were monitored 2 days a week each, for 9 weeks, from 8:00 am to 6:00 pm (360 hr of sampling). Results showed that adults use a wide range of call types, mainly related to courtship and the reproductive phase. Vocalisations are emitted especially by males and are a key element during mate attraction, nest building, in breeding events and in strengthening bonds within pairs. Most vocalisations are expressed in the first weeks of the breeding cycle, concurrently with the maximum number of courtship males, which exhibit most of the detected sound categories and emit calls with lower frequencies than females. Moreover, these vocalisations are expressed to a greater extent in the heronry characterized by an important forest component, where an almost entirely exclusive sound category was detected. In conclusion, the results suggest a possible correlation between vocal behaviour and female choice. The wide variety of sound signals and the high rate of calls produced by males during attraction and courtship displays, together with the acoustic characteristics of the signals, could provide honest estimates of the quality of emitters. [ABSTRACT FROM AUTHOR]

Acoustic communication among birds plays an important role in attracting mates and defending territories. For the successful transmission of songs, individuals of different species often avoid singing at the same time to reduce acoustic interference from background noise and overlapping signals from heterospecifics. Such behavioural acoustic niche partitioning may occur especially among closely related species due to their ecological similarities. In this study, we recorded bird sounds in a subtropical forest in China in May–June 2019 and detected seven cuckoo species. Extracting characteristics of the cuckoo calls, we found that only four of the 21 pairs of species overlapped in frequency range, and 19 pairs were classified accurately using a linear discriminant analysis classifier based on their features. The remaining two species pairs could be separated based on temporal or spatial distribution patterns. We also analysed the temporal distribution patterns and overlap time of the calls, finding that the seven species exhibit partitioning in at least one of three acoustic dimensions (site, frequency, activity time). We conclude that the seven sympatric cuckoo species were strongly partitioned in acoustic signal space and minimally masked each other's signals. [ABSTRACT FROM AUTHOR]

Observations of early vocal behaviours in non-human primates (hereafter primates) are important for direct comparisons between human and primate vocal development. However, direct observations of births and perinatal behaviour in wild primates are rare, and the initial stages of behavioural ontogeny usually remain undocumented. Here, we report direct observations of the birth of a wild chimpanzee (Pan troglodytes schweinfurthii) in Budongo Forest, Uganda, including the behaviour of the mother and other group members. We monitored the newborn's vocal behaviour for approximately 2 hours and recorded 70 calls. We categorised the vocalisations both qualitatively, using conventional call descriptions, and quantitatively, using cluster and discriminant acoustic analyses. We found evidence for acoustically distinct vocal units, produced both in isolation and in combination, including sequences akin to adult pant hoots, a vocal utterance regarded as the most complex vocal signal produced by this species. We concluded that chimpanzees possess the capacity to produce vocal sequences composed of different call types from birth, albeit in rudimentary forms. Our observations are in line with the idea that primate vocal repertoires are largely present from birth, with fine acoustic structures undergoing ontogenetic processes. Our study provides rare and valuable empirical data on perinatal behaviours in wild primates. [ABSTRACT FROM AUTHOR]

Animals can time their behaviours at predictable intervals. Their precision for doing so, however, may depend on the duration of the intervals. Laboratory experiments with animals show that timing precision decreases in proportion to the duration of the interval, a phenomenon known as scalar timing. In these experiments, animals are trained to wait for arbitrary intervals of time to get rewarded. In nature, animals time intervals as part of many stereotyped behaviours, regardless of whether the intervals are learned. It is unknown whether timing in this context is also scalar. Here, we tested for scalar timing in the song of the scaly-breasted wren, Microcerculus marginatus , which consists of whistles separated by intervals that increase in duration from less than 1 s to more than 10 s. We found that in nearly half of the songs, the timing of whistles was better explained by a model of constant precision rather than one of scalar timing. Moreover, in songs showing support for constant precision, the precision at the longest intervals was higher than that of nonhuman mammals and birds trained in the laboratory for timing presses at an operant device. The precision of the wren is also higher than that of humans, except when the latter count to increase their performance at timing. This study highlights the value of studying natural behaviours to uncover diverse strategies in interval timing among animals. • In Microcerculus marginatus songs, intervals increase from about 1 to 10 s in 0.5 s increments. • In many songs, the precision for timing intervals does not follow scalar timing. • Singing M. marginatus can be as precise as humans counting to time intervals. • Studying birdsong may reveal specialized neural mechanisms for precise timing. [ABSTRACT FROM AUTHOR]

Anthropogenic noise may significantly affect marine mammals' vocalizations. The aim of this work is to describe for the first time the acoustic features of the click trains, buzzes, burst pulses and whistles produced by the Risso's dolphins in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean), the concurrent levels of noise to which dolphins are exposed, and the potential reactive changes in the acoustic structure of the species vocalizations. About 6 h of recordings were collected from April 2019 to September 2022 during daytime boat surveys. Elevated ambient noise levels were mainly present at the frequencies lower than 63 Hz, at about 1 kHz and 50 kHz likely attributable to anthropogenic activity, such as shipping and sonars. Even if the acoustic features of all the vocalizations can be disrupted, especially with increasing noise below 1 kHz and between 20 and 63 kHz, the click trains were the most affected vocalizations, showing changes in their Inter-Click-Interval and in the Peak Amplitude. Since these vocalizations are used for navigation and searching for prey, their alteration raises concerns on the potential negative effects on the well-being of the Risso's dolphin population in the Gulf of Taranto. • Acoustic features of Risso's dolphin vocalizations in the Gulf of Taranto. • Description of concurrent levels of noise recorded in the Gulf of Taranto. • Vessel traffic and high frequency sonar affect acoustic structure of Risso's dolphin vocalizations. • The click trains were the most affected vocalization when noise levels increase. [ABSTRACT FROM AUTHOR]

This pilot study shows that wild bonobos display the fundamental temporal rules of vocal turn-taking Occurrences of calling patterns are in line with the unique observation collected from a captive group Calling patterns do not differ significantly with age and sex Calling patterns appear context-dependent In several species of non-human primates, non-agonistic vocal exchanges can be seen as a primitive form of conversation, as they respect basic temporal rules (i.e. turn-taking, overlap avoidance), the same as those that guide human conversations. Conversational rules have recently been suggested in captive great ape species, yet the only study investigating vocal turn-taking in wild great apes did not find any evidence of such vocal roles. Whether the environmental conditions (captivity versus free ranging) or the social organisation of a given species shape temporally ruled vocal exchanges remain open questions. Here, we investigated general calling patterns of peaceful vocal exchanges in a wild bonobo community. This pilot study revealed that wild bonobos respect the fundamental temporal rules of vocal turn-taking, namely the avoidance of overlapping and the presence of short call-intervals between interlocutors on the order of 2 sec, corroborating findings from captive bonobos. Despite the limited sample size, our finding suggests that vocal exchanges appear context-dependent but neither age nor sex seem to influence their occurrence. While further studies are needed to confirm these observations, this study helps to fill a major gap in research on the vocal communication of wild great apes, paving the way for more extensive comparative studies, representing a further step towards a better understanding of how vocal turn-taking arose in humans. [ABSTRACT FROM AUTHOR]

Long-distance vocalization is a characteristic of African lion, Panthera leo , behaviour and is important for maintaining territorial boundaries as well as locating distant group members. Vocal signalling is, however, a flexible behaviour that involves varying costs and benefits depending on environmental, social and spatial factors. Motivated by previous data collection limitations, we developed a novel approach to investigate the influence of atmospheric conditions and animal home range geography on lion vocal behaviour using acoustic and accelerometer biologgers. To compensate for the short lifetime of the acoustic biologger, we trained a machine-learning model to detect lion roars from long-term acceleration signals which yielded over 500 nights of data from seven individual lions. Analysis of detected roar events revealed that vocalizations occurred mainly at night with a peak just before dawn. The relative likelihood of vocalization was negatively related to wind speed and temperature and positively related to absolute humidity suggesting that lions preferred to roar under conditions that reduce sound attenuation and thereby maximize calling area. Roar occurrence was found to be dependent on an animal's location relative to its home range with lions demonstrating an apparent avoidance for vocalizing beyond the home range boundary. Lions were also more likely to roar repeatedly while closer to rivers and water points within their home range. This study is the first of its kind and not only improves the understanding of lion vocal behaviour but can also inform new approaches for recording animal vocalizations remotely. • Acoustic accelerometer biologgers enable detection of lion roars from body movement. • Lions vocalize mainly at night with a peak just before dawn. • Roaring is preferred when temperature and wind speed are low and humidity is high. • Lions avoid roaring beyond their home range boundary. • Lions are more likely to roar repeatedly when closer to rivers and water points. [ABSTRACT FROM AUTHOR]

Animal vocalisations can signify diverse behavioural contexts, knowledge of which can be applied in bioacoustic monitoring programs. Australia's endemic black cockatoos (Calyptorhynchus sp., family Cacatuidae) are highly vocal species that are threatened in many locations. In this study, we describe the nest‐associated vocal behaviours of two endangered subspecies of black cockatoo, the south‐eastern red‐tailed black cockatoo, C. banksii graptogyne and the Kangaroo Island glossy black cockatoo, C. lathami halmaturinus. Breeding success is limiting their recoveries and nest monitoring is challenging, but vocal recordings might provide valuable long‐term information hard to obtain otherwise. We recorded daily vocal activity at wild nests of both cockatoos using autonomous sound recorders. Combined with behavioural observations and video footage, we identified vocalisations characteristic of six behavioural contexts at nests: birds in flight, while perched, during begging (adult females), during courtship displays (adult males), when entering or sitting near to the nest hollow entrance (adult females), and from nestlings. Linear discriminant analysis on 12 acoustic measurements correctly classified 58.4% of calls of the red‐tailed black cockatoo (n = 907 calls from eight nests) and 62.9% of calls of the glossy black cockatoo (n = 1632 calls from 11 nests). In both subspecies, the female nest call and nestling calls are the most conspicuous vocal indicators of active nesting, and therefore should be considered for their bioacoustic potential. Other adult vocalisations indicate a range of behavioural contexts that could be informative for monitoring nesting behaviour, and its association to habitat features, in these endangered subspecies. [ABSTRACT FROM AUTHOR]

Individual vocal recognition (IVR) has been well studied in mammals and birds. These studies have primarily delved into understanding IVR in specific limited contexts (e.g. parent-offspring and mate recognition) where individuals discriminate one individual from all others. However, little research has examined IVR in more socially demanding circumstances, such as when an individual discriminates all individuals in their social or familial group apart. In this review, we describe what IVR is and suggest splitting studies of IVR into two general types based on what questions they answer (IVRsingular, and IVR-multiple). We explain how we currently test for IVR, and many of the benefits and drawbacks of different methods. We address why IVR is so prevalent in the animal kingdom, and the circumstances in which it is often found. Finally, we explain current weaknesses in IVR research including temporality, specificity, and taxonomic bias, and testing paradigms, and provide some solutions to address these weaknesses. [ABSTRACT FROM AUTHOR]

The dawn chorus of birds is an impressive display in which many individuals of a variety of species sing concurrently before sunrise. Brown Creeper (Certhia americana) is a small passerine bird that has not been well studied and is thought not to sing during the dawn chorus. Here, we used automated recordings to analyze Brown Creeper singing during the 2015-2017 breeding seasons from April through August in order to identify patterns in the timing and quantity of singing. We found that Brown Creepers did sing before sunrise, most often between April and early June and then more sporadically through mid July. We did not find any seasonal changes in song rates before sunrise, but we did find non-linear seasonal trends in both the timing and total duration of dawn singing bouts. Dawn choruses began earlier and lasted longer from April through mid June after which they began later and became shorter. Our results highlight the benefit of using automated recording techniques to study natural history of difficult to study species and add to our understanding of Brown Creeper natural history. [ABSTRACT FROM AUTHOR]

The minke whale (Balaenoptera acutorostrata) is a small species of baleen whale with a cosmopolitan distribution. Despite extensive study on the vocalizations of other balaenopterids, the acoustic repertoire of minke whales is not well known. Individuals of the North Pacific subspecies (B. acutorostrata scammoni) produce unique vocalizations ('boings') during their putative breeding season from fall to spring. However, no vocalizations have been previously reported for this subspecies in any eastern North Pacific feeding ground. We present two call types recorded in the presence of six minke whales, two of which were confirmed as female, in Cormorant Channel, British Columbia, Canada, during the summer of 2012. The calls consist of downsweeps and pulse chains. These call types share some characteristics with calls described elsewhere, although they are not identical to similar call types observed for other populations. Calling rates for minke whales in this study region are very low compared to those reported for this subspecies on its putative breeding grounds, as well as for other subspecies on their feeding grounds. We propose predation risk, sexual segregation and acoustic masking as potential causes of the low calling rates observed for minke whales in Cormorant Channel. [ABSTRACT FROM AUTHOR]

The acoustic communication of three species of social voles from the subgenus Sumeriomys – Microtus socialis (two subspecies: M. s. socialis and M. s. goriensis), M. paradoxus and M. hartingi – are described. Vole sound communication includes two main signals: squeaks and singing. The sounds made by M. hartingi have significantly higher frequency parameters than those of other species. Voles of all species squeak in situations of distress, and the males sing during courtship of the females. However, singing in social voles is not a necessary pattern for sexual behaviour: less than half of M. s. socialis and M. paradoxus males sang, M. hartingi sang even more rarely and M. s. goriensis did not demonstrate this behaviour at all. Despite the great similarity of the squeaks, its parameters differ significantly between species and differ from those of the common voles. This introduces one more argument that M. paradoxus and M. socialis are independent species, as are the subgenera Sumeriomys and Microtus. [ABSTRACT FROM AUTHOR]

The vocal repertoire of steppe (Lagurus lagurus Pallas, 1773) and yellow steppe (Eolagurus luteus Eversmann, 1840) lemmings consists of only one type of signal, namely, a squeak. The signal does, however, have considerable variability. The DFA standard procedure shows the significant differences in the parameters of squeaks between species and significant differences in squeak parameters between the sexes in steppe lemming but not in the yellow steppe lemming. The fundamental frequency of the smaller steppe lemming’s squeak is higher than that of the larger yellow steppe lemming, although the peak frequencies have comparable values. In addition, the steppe lemming displays a pronounced sexual dimorphism in vocalization parameters; the frequency characteristics of the signals of the smaller females have lower values, which are contrary to scaling laws, stating that smaller individuals tend to have higher fundamental and peak frequencies. The age-related variability in the signals of yellow steppe lemmings was also described. The fundamental frequency of their squeaks is higher than that of the adults, but the peak frequency of signals in young and adults is not distinguished, and its value is higher than theoretically calculated. Such deviation in signal frequency parameters from the optimum may be result of directed selection, indicating the high value of such signals in the acoustic communication of lemmings. [ABSTRACT FROM AUTHOR]

Vocal signals are important in territoriality and mate attraction across animal taxa. Vocalizations are particularly elaborate in some groups, such as songbirds, which learn their songs, but much remains to be known about the physiological mechanisms that produce variation, especially in vocalizations of nonlearners. We address the extent that androgen treatment of female and juvenile golden-collared manakins, Manacus vitellinus , activate the male-like 'chee-poo' vocalization to determine (1) the extent that the vocal circuitry is developed and sensitive to androgens in females and (2) to identify the characteristics, including finer acoustic features, of vocal behaviour that are influenced by androgens in females and young males. We analysed recordings of nonbreeding females and juvenile males given implants containing testosterone (T) or blank implants during a period of 3 weeks in an outdoor aviary in Panama. T-treated females, but not control females, produced chee-poos, and their vocalizations showed consistent differences in acoustic features from those of males. This indicates that the neuromuscular systems are well developed or relatively rapidly developed in response to T administration in females. Both T-treated and control juvenile males produced chee-poos, although vocal production was higher in the treatment group. Surprisingly, T treatment of juvenile males resulted in chee-poos with increased acoustic similarity to those of females, such as increased duration and frequency bandwidth. These features may indicate an important role for chee-poos in aggressive interactions. Future work will address the contributions of central and peripheral components in vocal variation in golden-collared manakins. Highlights • Sexual selection is often associated with the elaboration of male vocal signals. • Androgens guide sex differences in vocal output during early development. • Testosterone activated 'male-like' vocalizations in female golden-collared manakins. • Testosterone also influenced fine acoustic structure of juvenile male vocalizations. • Androgens may influence variation in vocal structure centrally or peripherally. [ABSTRACT FROM AUTHOR]

Purpose: Teachers are at a considerable risk of developing vocal health problems due to intensive voice use during teaching. This study investigated factors related to the teacher's voice during a teaching situation. Methods: Overall, 113 teachers were recorded during a typical class lesson, lasting on average 48 min. A portable voice dosimeter (VoxLog System) was used to measure the sound pressure level (SPL) of the noise in the classroom, the teacher's voice SPL, the fundamental frequency (fo) and the phonation time. General conditions of each lesson such as number of pupils, lesson subject and the educational level of the class were also collected. For the analysis, vocal loading doses and correlations between teacher's voice and noise SPL were calculated. Results: Voice and noise SPL values varied across the lesson subjects, with highest levels measured in sports lessons. The mean noise SPL changed throughout a lesson with highest values at the beginning and at the end of the lessons. The correlation analysis of voice and noise SPL identified two groups of teachers with different vocal SPL behaviours. For some teachers, the voice SPL varied with the noise SPL. For others, voice SPL was constantly high. A regression model on the teacher's voice SPL yielded a strong correlation with fo, the classroom noise SPL, and the individual vocal SPL behaviour. Conclusions: Classroom noise SPL and individual vocal SPL behaviour were significantly associated with teachers' voice SPL during teaching. Addressing these factors could be important steps in reducing the vocal load in teachers. [ABSTRACT FROM AUTHOR]

The ability to identify individuals within a population is often essential for a detailed understanding of the ecology and conservation of a species. However, some species, including large parrots, are notoriously difficult to catch and mark for individual identification. Palm cockatoos (Probosciger aterrimus) are a large, poorly understood species of parrot which are likely in severe decline within the eastern part – and possibly the western part – of their range on Cape York Peninsula, Australia. Here, we investigated whether three different palm cockatoo call types are sufficiently individually distinctive to function as a non-invasive “marker” for identifying individuals over time. Using Discriminant Function Analysis, overall identification accuracy among 12 putative individuals for all call types was 81% (i.e. 148 out of 183 calls were assigned to the correct individual) on the basis of multiple temporal, energy (amplitude) and frequency measurements on the spectrogram. For three different call types, individual identification accuracy among males and females ranged from 69 to 95%. However, based on a limited sample sizes of five putative individuals between years, our data suggest that individual call structure, as quantified by call parameters, was not stable between years. We discuss the applicability of these results for future studies of palm cockatoos and other parrot species. [ABSTRACT FROM AUTHOR]

Killer whales (Orcinus orca) are highly social top predators distributed throughout the world's oceans. They are divided into different ecotypes according to foraging specializations, phenotype, and social organization. For Northern Hemisphere killer whale ecotypes, acoustic behaviour has been shown to relate to foraging strategies and social organization. In contrast to the intensively studied Northern Hemisphere ecotypes, distribution patterns, social structures, and acoustic behaviour of the Southern Hemisphere killer whale ecotypes are poorly known. One of the Southern Hemisphere ecotypes, the Antarctic Ecotype C killer whale, is known to occur in regions with dense pack ice. The limited accessibility of these areas make passive acoustic monitoring (PAM) methods a very effective investigation tool to derive information on ecotype-specific abundance and distribution. During 2 d in February 2013, it was possible to collect concurrent visual and acoustic information of Ecotype C killer whales off the Antarctic continent. From these events, a call type catalogue was compiled. The 2,238 examined calls were subjectively classified into 26 discrete call types. Ten percent of the examined calls were re-classified by two additional independent observers to examine robustness of the classification. Mean classification accordance among observers was 68%. Most call types were composed of more than one call part. Sixty-five percent of all call types were monophonic, and 35% were biphonic. Almost two-third of all call types started with a short, broadband pulse. The variability within call types was relatively high. The Ecotype C vocal repertoire contained typical acoustic features such as biphonation, high call complexity, and generally high variability in frequency modulation. For future studies, the distinct characteristics of some of the call types described herein could potentially serve as acoustic markers for PAM-based differentiation of killer whale ecotypes in the Southern Ocean. [ABSTRACT FROM AUTHOR]

Language may be one of most important attributes which separates humans from other animal species. It has been suggested by some commentators that the primary biological function of human language is to deceive and selfishly manipulate social competitors. However, despite the existence of a large body of relevant theoretical and empirical literature in favour of the social bonding hypothesis for language function, the ostensible evidence and arguments for the deception hypothesis have not been fully discussed. The following review analyses the evidence and theoretical arguments from human social behavior, comparative animal behavior, and developmental psychology and suggests that deception shows clear signs of a derived function for language. Furthermore, in addition to being used relatively infrequently across most human and non-human animal contexts, deception appears to be utilized just as often for prosocial and social bonding functions, as it is for antisocial purposes. Future studies should focus on theoretical and experimental investigations which explore interactions between deceptive and honest language use in the context of social bonding.

Cetacean watching from tour boats has increased in recent years and has been promoted as an ethically viable alternative to cetacean viewing in captive facilities or directed take. However, short- and long-term impacts of this industry on the behaviour and energetic expenditure of cetaceans have been documented. Although multiple studies have investigated the acoustic response of dolphins to marine tourism, there are several covariates that could also explain some of these results and should be considered simultaneously. Here, we investigated whether common bottlenose dolphins, Tursiops truncatus , inhabiting Walvis Bay, Namibia vary their whistle parameters in relation to boat presence, surface behaviour and/or group composition. We detected an upward shift of up to 1.99 kHz in several whistle frequency parameters when dolphins were in the presence of one or more tour boats and the research vessel. No changes were demonstrated in the frequency range, number of inflection points or duration of whistles. A similar, although less pronounced difference was observed in response to engine noise generated by the research vessel when idling, suggesting that noise alone plays an important role in driving this shift in whistle frequency. Additionally, a strong effect of surface behaviour was observed, with the greatest difference in whistle parameters detected between resting and other behavioural states that are associated with higher degrees of emotional arousal. Group composition also contributed to the variation observed, with the impact of boats dependent on whether calves were present or not. Overall these results demonstrate high natural variation in the frequency parameters of whistles utilized by dolphins over varying behavioural states and group composition. Anthropogenic impact in the form of marine tour boats can influence the vocalization parameters of dolphins and such changes could have a long-term impact if they reduce the communication range of whistles or increase energy expenditure. [ABSTRACT FROM AUTHOR]

Long-distance calling is a common behaviour in animals, which has various important social functions. At a physiological level, calling is often mediated by gonadal hormones such as testosterone (T), particularly when its function is linked to intra-sexual competition for mates or territory. T also plays an important role in the development of vocal characteristics associated with dominance in humans. However, the few available studies of T and vocal behaviour in non-human primates suggest that in primates, T has less influence on call production than in other animals. We tested this hypothesis by studying the relationship between T concentrations and pant-hooting in wild male chimpanzees ( Pan troglodytes schweinfurthii) of the Kanyawara community in the Kibale National Park, Uganda. We found three kinds of correlation. Hourly T averages were positively associated with hourly rates of pant-hooting. Monthly T levels were likewise correlated with monthly rates of pant-hooting after controlling for other influences such as fission-fusion rates. Finally, males with high T levels had higher peak frequency at the start of the call climax. These results suggest that T affects the production of pant-hoots in chimpanzees. This implies that the pant-hoot call plays a role in male-male competition. We propose that even in cognitively sophisticated species, endocrine mechanisms can contribute to regulating vocal production. Significance statement: Many animals produce long-distance calls. The production of these calls is often modulated by gonadal hormones such as testosterone, especially if the calls are involved in competition between males for mates or territory. However, comparatively little is known about the influence of testosterone over the vocal behaviour of non-human primates, especially among great apes. In this study, we examined the relationship between testosterone and pant-hooting in wild male chimpanzees. We found that testosterone levels were associated with pant-hoot rates and one acoustic feature of the call. More specifically, males pant-hooted more often and produced pant-hoots with higher peak frequencies during periods of elevated testosterone levels. These results imply that gonadal hormones are involved in regulating vocal behaviour in chimpanzees and support the view that pant-hoots play a role in male-male competition. [ABSTRACT FROM AUTHOR]

Environmental noise is increasing worldwide, limiting the space available for species to send and receive important acoustic information. Many invasive species produce acoustic signals that alter the spectrotemporal characteristics of available signalling space. This provides an opportunity to test ideas about competitive exclusion by quantifying whether species with shared requirements for acoustic resources will become excluded or partition resource use to permit coexistence. We conducted a field playback experiment to test whether native treefrogs (green treefrogs, Hyla cinerea ; pine woods treefrogs, Hyla femoralis ) modify their acoustic behaviour to minimize acoustic competition from chorus noise of the invasive Cuban treefrog, Osteopilus septentrionalis . We demonstrate that noise from an invasive species differentially affects the vocal behaviour of native species. Those with similar calls ( H. cinerea ) shortened calls, called louder and persisted calling in response to masking stimuli while those with different calls ( H. femoralis ) did not modify behaviour. This evidence suggests that acoustic competition by invasive O. septentrionalis has altered the acoustic community structure, identifying acoustic competition as a mechanism by which invasive species can impact communities. Furthermore, these results broaden the concept of noise pollution, demonstrating fitness-relevant consequences of noise produced by invasive species. [ABSTRACT FROM AUTHOR]

Previous work has suggested that oral and manual systems co-emerge in a developing child which leads to the emergence of a more adult-like, precisely-timed coupling of gesture and speech (Iverson & Thelen, 1999). This study aimed to document the frequency of occurrence of vocalic and body movement gestures namely, hand, facial expression, facial movements and eye gaze in infants (using ELAN software) and to understand the emergence of vocal-motor link in a single typically developing child. The child was from a Kannada speaking family and the mother-infant dyad interactions were audio-video recorded once a month, from the 3rd to the 5th month. Results indicated that a typically developing infant is endowed with a repertoire of vocal, facial, and bodily signals and as young as 5 months there is a clear indication of strong vocalmotor linkage in expression. [ABSTRACT FROM AUTHOR]

Documenting the diversity of vocal behaviour across different avian taxa is key to understanding the ecology and evolution of complex behaviours. Unique to Cozumel Island in the Mexican Caribbean Sea, the Cozumel Wren ( Troglodytes aedon beani) provides an opportunity to investigate how isolation influences complex cultural traits. Most aspects of the biology, natural history, and taxonomy of Cozumel Wrens are unknown. In an attempt to better understand the Cozumel Wren's biology, we provide the first description of the songs and the vocal behaviour of this island-endemic bird. Based on more than 700 h of recordings, including more than 36,000 songs, we describe the fine structural characteristics of male Cozumel Wrens songs, and explore patterns of repertoire organization and song sharing. Cozumel Wrens sing songs composed of highly variable syllables, with prominent trills at the end of each song. Each bird has a limited repertoire of songs, which they create by recombining a restricted number of syllable and trill types. They repeat a song type several times before switching to a different one, with some variation in the number of times they repeat specific elements. Cozumel Wrens share more song types with neighbours than distant individuals. Syllable sharing, however, is equivalent between neighbours and distant individuals. Our results provide important data for future research on the ecology, evolution, and behaviour of this island-endemic songbird, and for helping to clarify the taxonomic status of Cozumel Wrens. [ABSTRACT FROM AUTHOR]

Acoustic properties of vocalizations arise through the interplay of neural control with the morphology and biomechanics of the sound generating organ, but in songbirds it is assumed that the main driver of acoustic diversity is variation in telencephalic motor control. Herewe show, however, that variation in the composition of the vibrating tissues, the labia, underlies diversity in one acoustic parameter, fundamental frequency (F0) range. Lateral asymmetry and arrangement of fibrous proteins in the labia into distinct layers is correlated with expanded F0 range of species. The composition of the vibrating tissues thus represents an important morphological foundation for the generation of a broad F0 range, indicating that morphological specialization lays the foundation for the evolution of complex acoustic repertoires. [ABSTRACT FROM AUTHOR]

The purposes of the study were to describe the vocal repertoire of the Red-crested Korhaan, (Lophotis ruficrista) and the nature and intensity of male call rivalry during the breeding season. Many hours of field sound data were recorded and behavioural observations were recorded in the field. During the breeding season two or three adult male Red-crested Korhaans group together in close proximity to one another at established sites (~2.4 ha), calling simultaneously and continuously, while performing aerial displays. The Red-crested Korhaan's repertoire consists of three basic calls. One of these, the peep call, was often uttered in four identifiable variations. The main function of these peep calls is to facilitate courtship and hence reproduction. The peeping call of males overlap to mask one another's calls. Alternate calling, and variations of the peep call, suggest that females are attracted to males that group together. Females respond to male peep calls at the start of the breeding season. [ABSTRACT FROM AUTHOR]

Vocal signals are very important in making the desired impression. They are the main determinants of the first impression, which influences interpersonal relations. In most public appearances broadcast in the media, the speaker has an immense influence on the interest of the receiver and maintaining his attention. The article concerns the ways of delivering public appearances by politicians, civil servants and spokespersons. Speakers were chosen so that in each dominates a different prosodic element easily distinguished by receivers. Among the most common are: frequent use of pause, excessive use of stress, not ending the sentence with a full stop, flat intonation, inadequate emotional tone of voice. This one dominating feature in the speaker's message influenced the poverty of melodic line. There was no effort to differentiate the way of presenting speeches, residing only on the most easily accessible feature. The analyzed examples are the most common media-present ways of speaking by public figures. They are an exemplification of reflections on the voice interpretation of a text: what elements of the spoken word can serve the purpose of the speaker, so that they make the desired impression on the audience. [ABSTRACT FROM AUTHOR]

Sound is the main means of communication for cetaceans, and studying their vocal behaviour can reveal important information about their activity patterns. As static acoustic monitoring (SAM) of whales, dolphins, and porpoises becomes more widespread, it is important to understand how data collected with automated click loggers relate to their behaviour. To assess whether behaviour can be inferred from automated click train data, echolocation click trains (series of clicks) of bottlenose dolphins and harbour porpoises recorded by C-PODs were examined with simultaneous visual observations. Recorded click trains from both species had different characteristics for the two observed behavioural categories: (1) travelling and (2) foraging. Foraging click trains for both species were of shorter duration and had shorter interclick intervals. The distinction in the click trains between the two behaviours was stronger for harbour porpoises. More than one quarter of the harbour porpoise click trains represented a distinct group of very fast click trains or "buzzes," which were thought to be associated with foraging, whereas only a small fraction of such trains was found in the bottlenose dolphin click data. For both species, the C-PODs showed potential in detecting foraging behaviour and in identifying potential feeding sites and trends in foraging activity. [ABSTRACT FROM AUTHOR]

Despite the high biodiversity that characterizes the tropics, we know little about the behaviour of most tropical birds. Antbirds (Thamnophilidae) are a biodiverse family of more than 200 species found throughout Central and South America, yet their ecology and behaviour are poorly known. In this study, we provide the first detailed description of the vocalizations and vocal behaviour of Barred Antshrikes ( Thamnophilus doliatus), a widespread Neotropical suboscine passerine. We studied 38 territorial pairs in a population in Costa Rica from 2008 to 2010, using field recordings and observations to quantify their vocalizations and vocal behaviour. Males and females produced similar songs consisting of rapidly repeated chuckling notes. Several aspects of their songs distinguish the sexes: male songs were longer in duration, contained more syllables, and were lower in pitch. Males had a higher song output than females, but within song bouts males and females sang at similar rates. Barred Antshrike song output varied daily, with the highest song output occurring at dawn. Song output also varied seasonally, with increased song output occurring during the breeding period. Males and females combined songs to create duets, overlapping the terminal portion of their mate's song. Most duets were created by females responding to male songs (84 %), and the rest by males responding to female songs. The timing of duet responsiveness varied between the sexes; males responded more quickly to their partner's song (1.6 s) than females (2.0 s). This detailed account of the vocalizations and vocal behaviour of a population of Barred Antshrikes creates a foundation for future comparative studies of antbirds. Our study highlights similarities and differences in the behavioural patterns of tropical birds and contributes to our understanding of the function of vocal duets and the vocal behaviour of antbirds. [ABSTRACT FROM AUTHOR]

Detailed information is still lacking on structure and duration of calls of diurnal birds of prey as well on their vocal repertoire. The Lanner Falcon ( Falco biarmicus) is considered a shy less-vociferous species but no quantitative data exist. Field evidence demonstrates that in the last decades this falcon did not improve its threatened status in Italy. We investigated call frequencies and their durations to ascertain the effectiveness of these signals, especially during the breeding season. In particular, if calls are honest signals about the genetic quality of males. We carried out this study during two breeding seasons in eastern Sicily where we monitored 25 nesting attempts at 19 breeding sites. During 114 observational sessions, we recorded (1) which sex uttered calls, (2) type of vocalisation (wailing and creaking calls) and (3) bird positions (flying or perched). In addition, we recorded duration of each vocal event because it seems to be significantly correlated with male quality. We checked nests annually to ascertain the number, age and gender of nestlings. Lanner mates employ calls mainly in crucial reproductive stages (courtship, incubation, the first week after hatching and when young are fledging) optimising their efforts. In addition, males performing shorter vocal events produce broods significantly smaller in size and with a sex ratio biased towards females. In addition, they seem to desert the breeding site in the subsequent year. We suppose that in Italian fragmented breeding populations of Lanners, call structure and rates can predict population viability. [ABSTRACT FROM AUTHOR]

The article discusses a study on stereotypic behavior in the species of Peromyscus and Onychomys, a monophyletic group of rodents. The behavior helps in determining the evolutionary characters and systematic relationships among the species. The study depicts that vocalization among the Peromyscus species is loud but with modulated frequency and Onychomys produces loud but constant frequency vocalization. Several tables depicting the vocalization difference among the species are presented.

Abstract: Many laboratories are conducting research using songbirds as their animal model. In particular, songbirds are widely used for studying the behavioural and neural mechanisms underlying vocal learning. Many researchers use wild-caught birds to conduct this research, although few studies of behaviour have been conducted to determine the effects of captive housing on these species. We investigated the vocal production pattern of wild-caught black-capped chickadees (Poecile atricapillus) over an entire season in laboratory housing. We documented the frequency of production of four vocalizations (fee-bee song, chick-a-dee calls, dee calls, and gargle calls) across seasons and diurnal pattern and compared the observed pattern of laboratory vocalizations to those previously observed and reported in the wild. Laboratory-housed chickadees had seasonal and diurnal vocal production shifts that were related to both photoperiodic changes (season) and diurnal pattern. For instance, there was significantly more fee-bee song in the spring than summer, autumn, and winter with the most fee-bee song occurring at spring dawn as seen in the wild. Our results also confirmed that the general pattern of vocalizations was consistent between wild and laboratory populations, with no significant differences for either the seasonal or diurnal pattern of fee-bee song production between populations. Differences between settings were observed in the pattern of chick-a-dee calls at dawn and sunset between field and laboratory populations. However, differences in the quantity of vocalization types between laboratory and wild populations suggest that housing conditions are influencing the normal vocal behavioural patterns. [Copyright &y& Elsevier]

For most frogs, advertisement calls are essential for reproductive success, conveying information on species identity, male quality, sexual state and location. While the evolutionary divergence of call characters has been examined in a number of species, the relative impacts of genetic drift or natural and sexual selection remain unclear. Insights into the evolutionary trajectory of vocal signals can be gained by examining how advertisement calls vary in a phylogenetic context. Evolution by genetic drift would be supported if more closely related species express more similar songs. Conversely, a poor correlation between evolutionary history and song expression would suggest evolution shaped by natural or sexual selection. Here, we measure seven song characters in 20 described and two undescribed species of African clawed frogs (genera Xenopus and Silurana) and four populations of X. laevis. We identify three call types - click, burst and trill - that can be distinguished by click number, call rate and intensity modulation. A fourth type is biphasic, consisting of two of the above. Call types vary in complexity from the simplest, a click, to the most complex, a biphasic call. Maximum parsimony analysis of variation in call type suggests that the ancestral type was of intermediate complexity. Each call type evolved independently more than once and call type is typically not shared by closely related species. These results indicate that call type is homoplasious and has low phylogenetic signal. We conclude that the evolution of call type is not due to genetic drift, but is under selective pressure. [ABSTRACT FROM AUTHOR]

Social animals may develop behavioural strategies that are based on individualized relationships among members. In these cases, there might be selection pressures for the development of identity signals and mechanisms that allow discrimination and recognition of particular individuals. Female sperm whales, Physeter macrocephalus, live in long-term, stable social units. Differential interactions among unit members suggest the need for an individual discrimination system. Sperm whales produce stereotyped series of click sounds called codas, which are thought to be used for communication. Although codas were initially proposed as individual signatures, later studies did not support this hypothesis. Using linear discriminant functions and Mantel tests, we tested variation within coda types as a means for individual identification, using recordings where codas were assigned to individual whales. While most coda types showed no indication of individual-specific information, individual differences that were robust to variation among recording days were found in the 5 Regular coda type. Differences in individual-specific information between coda types suggest that different coda types may have distinct functions. [ABSTRACT FROM AUTHOR]

Animals often produce sounds that are focused in a particular direction relative to the caller’s orientation. Although many studies have suggested ways in which directional signal design might have behavioural significance among vocally interacting individuals, there are few direct tests using experimental approaches. During the breeding season and while fasting on land, male northern elephant seals produce airborne threat calls during dyadic interactions when competing for mating opportunities. In this study, we investigated the directional cues of these calls and tested hypotheses regarding directional signalling with respect to the behaviour of receivers during vocally mediated male agonistic interactions. We then determined effects of vocal directionality on receiver responses using an acoustic playback approach. We found that male calls had substantial directionality, particularly at higher frequencies (>1000Hz). Subordinate males responded more strongly by retreating when the caller faced the receiver compared to when the caller was at a right angle or faced away. We also found a significant difference in responses to playback sequences with different call directivity patterns. Males displayed significantly more negative phonotaxis (i.e. moved away) in response to playbacks that simulated a caller oriented towards them compared to when playbacks simulated a caller oriented away from them. These results suggest that the directionality of threat calls provides important information about the auditory scene and spatial orientation of conspecifics and that this trait, along with the receiver’s ability to extract this information, may have evolved as a consequence of its effect on the breeding success and fitness of the individual. [ABSTRACT FROM AUTHOR]

The great reed warbler, Acrocephalus arundinaceus, is one of the most intensively studied species in the area of vocal behaviour and an important model in studies of sexual selection. We evaluated performance of the whistles produced by different males and examined whether individuals improved their performance over consecutive seasons. Finally, we tested whether the performance of whistles reflected males’ philopatry and harem size. We assessed whistle performance based on duration and consistency. Our analyses showed that great reed warbler males improved the performance of their whistles in subsequent seasons. Whistles became both longer and more consistent from one year to the next. We also found that males’ harem size was significantly related to whistle performance, which in turn reflected philopatry. Subsequent analyses revealed that the performances of polygynous and philopatric males differed significantly from those of monogamous, unpaired and new males. As philopatry is preferred by great reed warbler females, it is in the males’ interest to advertise this feature. Coding philopatry in the songs of individual males seems to be an easy and efficient way of informing females about males’ familiarity with the breeding grounds. The proper performance of difficult double-element whistles, the mastery of which may be time consuming, seems to be a good candidate for indicating males’ philopatry. If so, the quality of whistle syllables may also reflect differences in the general quality of individual males as high performance levels may be associated with both males’ longevity and their ability to learn. [Copyright &y& Elsevier]

The article discusses a study which examines the use of the so-called laryngeal twittering calls produced by shrews for communication or orientation based on echo. The study noted that the call rates in common shrews and white-toothed species were not affected by higher likelihood of conspecific which is olfactorily simulated. The authors say that their ensonification research revealed the potential of shrew-like calls to produce echo scenes which can be used in habitat assessment.

Acoustic-based monitoring has proved useful for many birds and seems promising for the endangered red-crowned crane. However, its validity in crane conservation is unclear in the absence of knowledge concerning the long-term stability of pair-specific duets. The red-crowned crane is monogamous and long-lived, with stable pair bonding both within and between years. Pair mates perform loud duets—a succession of male and female calls emitted with definite temporal coordination. We examined the stability of duets for five captive pairs over five years (2003–2007) on the basis of analysis of the syllables within the duets. MANOVA showed that the effect of pair identity on syllable characteristics was always stronger than the effect of the year of recording. Cross-validation of duets from 2004, 2005, 2006, and 2007 with discriminant analysis (DFA) functions derived, respectively, from pooled samples from 2003, 2003–2004, 2003–2005, and 2003–2006 resulted in comparably high percentages of correct classification into pairs. The pairs could be reliably identified by their duets and pair-specific differences in syllable characteristics were stable with time. These data suggest acoustic monitoring is a feasible alternative to more invasive methods of identification. [ABSTRACT FROM AUTHOR]

Abstract: The genetic basis of the effects of domestication has previously been examined in relation to morphological, physiological and behavioural traits, but not for vocalizations. According to Belyaev [Belyaev, D.K., 1979. Destabilizing selection as a factor in domestication. J. Hered. 70, 301–308], directional selection for tame behaviour toward humans resulted in domestication. This hypothesis has been confirmed experimentally on the farm-bred silver fox Vulpes vulpes population that has undergone 45 years of artificial selection for tameness and 35 years of selection for aggressiveness. These foxes, with their precisely known attitudes toward people, provide a means of examining vocal indicators of tameness and aggressiveness to establish the genetic basis for vocal production in canids. We examined vocalizations toward people in foxes selected for tameness and aggressiveness compared to those of three kinds of crosses: Hybrids (Tame×Aggressive), A-Backcrosses (Aggressive×Hybrid) and T-Backcrosses (Tame×Hybrid). We report the effects of selection for tameness on usage and structure of different vocalizations and suggest that vocal indicators for tameness and aggressiveness toward people are discrete phenotypic traits in silver foxes. [Copyright &y& Elsevier]