Song Structure Research Articles

Song structure and singing activity of two separate humpback whales populations wintering off the coast of Caño Island in Costa Rica.

Central American (CA) and Breeding Stock-G (BSG) humpback whales are known to winter off Caño Island, Costa Rica at different times of the year. To study their singing behavior, autonomous underwater recorders were used to record the whales. Song detection for BSG whales was higher than CA whales, and song structure was distinct for each population. No strong evidence for cross-equatorial connectivity was found. This study provides the first humpback whale song reference for both populations in Costa Rica, which can help advance understanding of CA and BSG whale song rate of change and connectivity with other wintering areas.

Inhibitory cell populations depend on age, sex, and prior experience across a neural network for Critical Period learning

In many ways, the complement of cell subtypes determines the information processing that a local brain circuit can perform. For example, the balance of excitatory and inhibitory (E/I) signaling within a brain region contributes to response magnitude and specificity in ways that influence the effectiveness of information processing. An extreme example of response changes to sensory information occur across Critical Periods (CPs). In primary mammalian visual cortex, GAD65 and parvalbumin inhibitory cell types in particular control experience-dependent responses during a CP. Here, we test how the density of GAD65- and parvalbumin-expressing cells may inform on a CP for complex behavioral learning. Juvenile male zebra finch songbirds (females cannot sing) learn to sing through coordinated sensory, sensorimotor, and motor learning processes distributed throughout a well-defined neural network. There is a CP for sensory learning, the process by which a young male forms a memory of his “tutor’s” song, which is then used to guide the young bird’s emerging song structure. We quantified the effect of sex and experience with a tutor on the cell densities of GAD65- and parvalbumin-expressing cells across major nodes of the song network, using ages that span the CP for tutor song memorization. As a resource, we also include whole-brain mapping data for both genes. Results indicate that inhibitory cell populations differ across sex, age, and experiential conditions, but not always in the ways we predicted.

Song characters as reliable indicators of male reproductive quality in the Savannah Sparrow (Passerculus sandwichensis)

Bird song may provide female birds with signals of male quality. To investigate this potential for sexual selection via female choice, we assessed the relationships between male song variation and male mating and reproductive success of the Savannah Sparrow (Passerculus sandwichensis (J.F. Gmelin, 1789)) over 3 years (2001–2003) in a population of Savannah Sparrows near London, Ontario, Canada. We measured song rate, as well as temporal and frequency attributes of song structure, as possible predictors of male quality, and then related these measures to attributes of male reproductive performance (mating and breeding success and territory size of males). We found significant correlations between male reproductive performance and several song features, such that the combined effects of two trill sections could potentially play an important role: males possessing such songs arrived and paired earlier and had higher fledging success. The results suggested that the trill segments of the song may signal important aspects of male quality. Possible reasons for significant roles of such songs in open-habitat birds are discussed.

Transcriptional regulatory divergence underpinning species-specific learned vocalization in songbirds.

Learning of most motor skills is constrained in a species-specific manner. However, the proximate mechanisms underlying species-specific learned behaviors remain poorly understood. Songbirds acquire species-specific songs through learning, which is hypothesized to depend on species-specific patterns of gene expression in functionally specialized brain regions for vocal learning and production, called song nuclei. Here, we leveraged two closely related songbird species, zebra finch, owl finch, and their interspecific first-generation (F1) hybrids, to relate transcriptional regulatory divergence between species with the production of species-specific songs. We quantified genome-wide gene expression in both species and compared this with allele-specific expression in F1 hybrids to identify genes whose expression in song nuclei is regulated by species divergence in either cis- or trans-regulation. We found that divergence in transcriptional regulation altered the expression of approximately 10% of total transcribed genes and was linked to differential gene expression between the two species. Furthermore, trans-regulatory changes were more prevalent than cis-regulatory and were associated with synaptic formation and transmission in song nucleus RA, the avian analog of the mammalian laryngeal motor cortex. We identified brain-derived neurotrophic factor (BDNF) as an upstream mediator of trans-regulated genes in RA, with a significant correlation between individual variation in BDNF expression level and species-specific song phenotypes in F1 hybrids. This was supported by the fact that the pharmacological overactivation of BDNF receptors altered the expression of its trans-regulated genes in the RA, thus disrupting the learned song structures of adult zebra finch songs at the acoustic and sequence levels. These results demonstrate functional neurogenetic associations between divergence in region-specific transcriptional regulation and species-specific learned behaviors.

Diversification in trophic morphology and a mating signal are coupled in the early stages of sympatric divergence in crossbills

AbstractUnderstanding the mechanisms generating diversity in mating signals is critical to understanding the process of speciation. One mechanism of mating signal diversification occurs when phenotypes that experience divergent ecological selection also affect the production of mating signals, resulting in a coupling between ecological diversification and mating signal diversification. Here, we present evidence that rapid diversification in bill size has resulted in the diversification of some components of song structure in a young adaptive radiation of seed-eating finches (red crossbill, Loxia curvirostra complex). Specifically, we find that larger-billed ecotypes sing songs with lower minimum frequencies, lower syllable repetition rates and greater vocal deviation (i.e. lower performance) than smaller-billed ecotypes for pure tonal syllables. In contrast, bill size was not correlated with maximum frequency or frequency bandwidth, and we found no relationship between bill size and any song parameters in buzzy syllables. Furthermore, we found no evidence for a relationship between the degree of bill size divergence and the potential for song discrimination between sympatric ecotypes. Because bill size is correlated with some features of pure tonal syllables (which appear to be most important for courtship in crossbills) in crossbill song, our results suggest that there was an early-evolving link between ecological and mating signal diversification that may have influenced the rapid evolution of reproductive isolation between sympatric ecotypes.

Singing behind the stage: thrush nightingales produce more variable songs on their wintering grounds

The songs of migratory passerine birds have a key role in mate attraction and territory defence during the breeding season. Many species also sing on their wintering grounds, but the function of this behaviour remains unclear. One possible explanation, proposed by the song improvement hypothesis, is that the birds take advantage of this period to develop their singing skills for the next breeding season. If so, non-breeding songs should reflect features of an early phase in song development, characterized by high vocal plasticity. In our study, we tested this prediction by comparing songs of thrush nightingales (Luscinia luscinia) recorded at two different breeding areas in Europe and one wintering area in Africa. While all songs from European localities had a typical structure characteristic of the study species, 89% of the songs recorded from Africa were highly variable, lacking such typical structure. We conducted further detailed analysis of breeding and winter songs that exhibited species-specific structure. First, we explored plasticity at the syllable level using a cross-correlation analysis, to obtain similarity scores as a measure of consistency. Second, we asked multiple human observers to quantify element variability. Our results showed significant differences in syllable consistency between breeding and wintering grounds, with more consistent delivery of syllables in the breeding areas. Likewise, element variability was substantially lower in the breeding populations. While both results fit the predictions of the song improvement hypothesis, more research is needed to elucidate the roles of singing on the wintering grounds. Many migratory songbirds sing on their wintering grounds, outside the breeding period. While the role of singing during breeding has been broadly studied, our understanding of the function of winter singing remains limited. We analysed songs of the thrush nightingale, a migratory songbird with highly complex songs, comparing song structures recorded from breeding populations in Europe and an African wintering site. We demonstrate that males recorded at wintering locations sang songs with both significantly lower syllable consistency and higher element variability. Such characteristics are comparable to those observed during the sensorimotor phase of song development, previously described in other species. This pattern supports the song improvement hypothesis, suggesting that males singing on the wintering grounds may practice songs for the next breeding season. This study contributes to the understanding of the functions of songbird vocal behaviour out of the breeding context.

Vocal Response of Oriental Magpie Robin (Copsychus saularis) to Urban Environmental Factors in Peninsular Malaysia

Anthropogenic noise and changes in environmental gradients resulted from urbanisation have been shown to alter vocalisation of urban birds in previous studies. This study examined the vocalisation of the Oriental Magpie Robin(Copsychus saularis; locally known as Murai Kampung) in relation to anthropogenic noise and environmental factors in the urban, suburban and rural areas in Peninsular Malaysia. We measured four ambient factors (i.e. ambient noise, temperature, relative humidity and light intensity) and two landscape factors (i.e. distance to building and distance to major roads) between January and June 2017 from six locations. A total of 147 recordings comprising territorial songs of the bird were obtained and transcribed into spectrograms. Six parameters, namely lowfrequency, high frequency, frequency ranges, length of strophe, number of elements per strophe, and time interval between strophes were derived from spectrograms for each recording. In urban areas, low frequency of the songs was found to have increased significantly as compared to those recorded in suburban and rural areas. The difference in noise, temperature and relative humidity in urban and suburban environment had led to both single and interaction effects towards the Oriental Magpie Robin’s song parameters, i.e. low frequency, length of strophe, time interval between strophes and number of elements per strophe. The results evidenced the ability of the Oriental Magpie Robin in regulating and altering their song structure according to itssurrounding environment. This implies its vocal plasticity which is important in ensuring the efficiency in transmission of songs and is likely to explain why the bird is less susceptible to urbanisation.

Corticobasal ganglia projecting neurons are required for juvenile vocal learning but not for adult vocal plasticity in songbirds

Birdsong, like human speech, consists of a sequence of temporally precise movements acquired through vocal learning. The learning of such sequential vocalizations depends on the neural function of the motor cortex and basal ganglia. However, it is unknown how the connections between cortical and basal ganglia components contribute to vocal motor skill learning, as mammalian motor cortices serve multiple types of motor action and most experimentally tractable animals do not exhibit vocal learning. Here, we leveraged the zebra finch, a songbird, as an animal model to explore the function of the connectivity between cortex-like (HVC) and basal ganglia (area X), connected by HVC(X) projection neurons with temporally precise firing during singing. By specifically ablating HVC(X) neurons, juvenile zebra finches failed to copy tutored syllable acoustics and developed temporally unstable songs with less sequence consistency. In contrast, HVC(X)-ablated adults did not alter their learned song structure, but generated acoustic fluctuations and responded to auditory feedback disruption by the introduction of song deterioration, as did normal adults. These results indicate that the corticobasal ganglia input is important for learning the acoustic and temporal aspects of song structure, but not for generating vocal fluctuations that contribute to the maintenance of an already learned vocal pattern.

An analysis of avian vocal performance at the note and song levels

ABSTRACT Sexual displays that require extreme feats of physiological performance have the potential to reliably indicate the signaller’s skill or motivation. We tested for evidence of performance constraints in Adelaide’s warblers (Setophaga adelaidae) songs. At the note level, we identified three trade-offs with well-defined limits. At the song level, we identified two trade-offs, but their limits were less well-defined than the note-level limits. Trade-offs at both levels suggest that song structure is constrained by limits to the speed of both frequency modulation (while vocalising and between notes) and respiration. Performance metrics derived from the observed limits to performance varied moderately among individuals and strongly among song types. Note-level performance metrics were positively skewed, as predicted by the hypothesis that performance is constrained. We conclude that physiological limits on frequency modulation and respiration constrain song structure in male Adelaide’s warblers. Further work is needed to determine whether receivers respond to natural levels of variation in performance, and whether performance correlates with singer quality or motivation.

Integrative passive acoustic monitoring in Monterey Bay National Marine Sanctuary

Monterey Bay National Marine Sanctuary, in the highly productive California Current System, is vital habitat for many marine mammal species. Passive acoustic monitoring (PAM) is an effective means to detect species’ presence and acoustic behavior. Using the infrastructure of a cabled observatory and detection and classification of sound sources, we examine applications of PAM as an essential part of ecosystem-based research and management. The first case study integrates PAM with multidisciplinary data—whale sighting rates, forage species’ abundances, levels of primary production, concentrations of a neurotoxic algal compound, and acoustic modeling results—to examine how occurrence patterns of humpback whale song reflect ecosystem variations. The second case study takes a similar approach to examine blue whale call occurrence, with emphasis on varying detection and classification methods for different call types. The third case study examines an anthropogenic sound source: explosives intended to deter interference of pinnipeds in fishing operations. Toward new developments that are proving insightful, we consider three further approaches: (1) application of unsupervised machine learning methods to advance characterization of humpback whale song structure; (2) integration of PAM and active acoustic sensing to examine predator-prey relationships; and (3) integration of PAM time-series analyses with data from animal tags.

Habitat-related differences in song structure and complexity in a songbird with a large repertoire

BackgroundUrbanisation has been shown to influence many aspects of animal vocal communication. Much attention has been paid to anthropogenic noise, which is often described as one of the most challenging disturbances for urban dwellers. While a large body of literature describes associations between vocal behavior of avian populations and background noise level, most of these studies were conducted on species with relatively simple songs and small repertoire sizes. This study focuses on the song thrush, Turdus philomelos, a common Eurasian songbird with a complex singing style and large syllable repertoire. Our objective was to determine whether frequency, repertoire and temporal organisation of song parameters vary between birds inhabiting urban and adjacent forest habitats in which ambient noise levels differ.ResultsSongs of urban males were found to be more complex than in conspecifics from natural forest populations. Urban dwellers possessed greater syllable repertoires and repeated syllable sequences more often. In addition, they used a smaller proportion of whistles and a higher proportion of twitter syllables when singing compared to the nonurban males. Moreover, we found significant differences in the minimum and peak frequency of the whistle syllable between studied populations.ConclusionsThese findings may be an example of adaptation of acoustic communication in noisy urban environments, but we also discuss other possible explanations. We emphasize the need for further investigation into the relationships between birdsong and habitat characteristics, male quality, population density and ambient noise level in populations occupying urban and nonurban habitats.

RECEPTION OF THE BOOK OF PSALMS IN M. OPITZ’S POETRY (THE PROBLEM OF BIBLICAL ARCHETEXTUALITY)

The problem of relationship between fiction and «axial» archetext of Christian culture and European literature, the Bible, is an important problem of contemporary literature. The Bible is not only a religious text, but also a literaty one. It includes outstanding examples of poetry and The Book of Psalms that is an anthology of ancient Hebrew religious and philosophical poetry clearly representing a dialogue between I and the Eternal Thou (in M. Buber’s terminology). The significance of the Bible has an especially high level for the development of German religious and philosophical poetry. In the article the author studies an archetextual role of The Book of Psalms in Martin Opitz’s (1597–1639) poetry using cultural and historical, comparative, hermeneutic methods and a method of textual holistic analysis. M. Opitz is the first of German poets, who turns to the genres of paraphrase of Psalm and spiritual song. M. Opitz starts with penitential Psalms for paraphrasing. He makes the concept of guilt and confession deeper and considers it a means of withdrawal from the spiritual crisis and prevention of a national tragedy. Following the logic and structure of Psalms, which also play the role of architexts, the German poet explains and complements them, correlates them with his time, going after the moral and didactical purpose above all. Futhermore, he is the first to use consistent accentualsyllabic verse introduced by him and song structures so that his paraphrases are remembered by people. Spiritual songs which contain numerous allusions on Psalms are characterized by shorter metre and simpler syntax. While the poetics of baroque prevails in the paraphrases of Psalms, the tendencies of classicism are more expressive in the spiritual songs. Paraphrases of Psalms and spiritual songs by M. Opitz connect personal and national ground, expression of suffering and hope for transformation of life during hard times for Germany viz. the epoch of Thirty Years’ Wars.

Visual and passive acoustic observations of blue whale trios from two distinct populations

Visual and passive acoustic observations of blue whale trios from two distinct populations

О доминирующей роли одной звуковысотной структуры в песенной традиции луговых (сернурских) мари

One of the foreground directions of Mari ethnomusicology is the research of pitch organization of song tunes. Certain particular results in this sphere in relation to the song tradition of the field Mari have been achieved by scholars in Russia and in other countries. However, many questions connected with the pitch-related characteristics of the songs in their coordination with the metrorhythmic, compositional and timbral laws have remained beyond the field of sight of researchers. The article is devoted to the modal organization of the melodies of the Sernur Mari – one of the local groups of the field Mari. The foundation for highlighting this subethnic groups among the other groups of the field Mari was that the traditional culture of the Sernur Mari is distinguished by a whole set of characteristic peculiarities: the parlance, the complex of costumes, the calendar cycle, and the musical language. A significant element defining the local style of the Sernur Mari is the pitch characteristic features of the melodies. The basic element in them is the five-step scale in the ambitus of a sixth – g-b-c1-d1-e1. The article analyzes the realization of the hemitonic modal structure in wedding, guest and lyrical songs, differing from each other on the levels of the rhythmic organization and melodic composition of the songs’ stanzas. The numerous recordings of songs in various genres made during folk music expeditions and the work on analysis carried out make it possible to come to the conclusion that the hemitonic modal structure determines the specific features of the musical culture of the Sernur Mari, distinguishing it from the other local traditions of the field Mari. Keywords: the field Mari, the Sernur Mari, the song tradition, pitch structure, hemitonic pentatonics.

Social context mediates testosterone's effect on snort acoustics in male hyrax songs

Testosterone affects physical and motivational states, both of which may strongly influence vocalization structure and acoustics. The loud complex calls (i.e., songs) of male rock hyraxes (Procavia capensis) are used as honest signals for advertising physical and social states. The snort, a low frequency, noisy element of the song, encodes information on the singer's age and social rank via harshness, as measured by jitter (i.e., acoustic frequency stability) and duration; suggesting that the snort concomitantly advertises both vocal stability and aggression. Our past findings revealed that testosterone levels are related to both vocal elements and social status of male hyraxes, suggesting that hormonal mechanisms mediate the motivation for aggressive and courtship behaviors. Here we examined whether long-term androgen levels are related to snort acoustics and song structure by comparing levels of testosterone in hair with acoustic and structural parameters. We found that songs performed by individuals with higher testosterone levels include more singing bouts and longer, smoother snorts, but only in those songs induced by external triggers. It is possible that hyraxes with higher levels of testosterone possess the ability to perform higher-quality singing, but only invest in situations of high social arousal and potential benefit. Surprisingly, in spontaneous songs, hyraxes with high testosterone were found to snort more harshly than low-testosterone males. The context dependent effects of high testosterone on snort acoustics suggest that the aggressive emotional arousal associated with testosterone is naturally reflected in the jittery hyrax snort, but that it can be masked by high-quality performance.

The song structure and repertoire size of Daurian Redstarts (Phoenicurusauroreus) in South Korea

The song repertoire across avian species varies considerably in size, and reliable measurement is important in defining its significance as a target in sexual selection. In this study, the song structure and song repertoire size of the Daurian Redstart (Phoenicurus auroreus) in South Korea were investigated. The songs had major syllable variation rather than song type variation. The average song repertoire size from 20 males was 39.9 ± 5.8 (range: 28-50), based on a syllable type that was appropriate for this species. The songs were structured with three distinguishable parts, where song syllables varied most in the syllable part, and new syllable additions were relatively limited in the whistle and subsyllable parts. Furthermore, new syllables were gradually reduced with an increasing number of males, potentially due to the existence of core syllables in the songs. Our results suggest an individual identity cue may exist in the syllable part of the song and that the less variable whistles within and between individuals may play a role in forming a local dialect. Thus, further research on syllable similarity is needed to find song variations among individuals over greater geographic distances.

Robust singer identification of Indian playback singers

Singing voice analysis has been a topic of research to assist several applications in the domain of music information retrieval system. One such major area is singer identification (SID). There has been enormous increase in production of movies and songs in Bollywood industry over the last 50 decades. Surveying this extensive dataset of singers, the paper presents singer identification system for Indian playback singers. Four acoustic features namely—formants, harmonic spectral envelope, vibrato, and timbre—that uniquely describe the singer are extracted from the singing voice segments. Using the combination of these multiple acoustic features, we address the major challenges in SID like the variations in singer’s voice, testing of multilingual songs, and the album effect. Systematic evaluation shows the SID is robust against the variations in singer’s singing style and structure of songs and is effective in identifying the cover songs and singers. The results are investigated on in-house cappella database consisting of 26 singers and 550 songs. By performing dimension reduction of the feature vector and using Support Vector Machine classifier, we achieved an accuracy of 86% using fourfold cross validation process. In addition, performance comparison of the proposed work with other existing approaches reveals the superiority in terms of volume of dataset and song duration.

Structure of Lark Sparrow Song in California

Structure of Lark Sparrow Song in California

50 to 30-Hz triplet and singlet down sweep vocalizations produced by sei whales (Balaenoptera borealis) in the western North Atlantic Ocean.

The life history, distribution, and acoustic ecology of the sei whale (Balaenoptera borealis) in the western North Atlantic Ocean remains poorly understood. In this study an array of bottom-mounted recorders captured previously undocumented low frequency 50 to 30-Hz triplet and singlet down sweep vocalizations in close association with signature 82 to 34-Hz sei whale down sweep vocalizations. Spatiotemporal correlations of acoustically tracked sei whales confirm the original vocalizations are produced by sei whales. The 50 to 34-Hz down sweep call types were characterized with a suite of five spectral and temporal measurements. The pattern and repetition of the full acoustic suite is suggestive of song structure and warrants further investigation. The discovery of vocalizations attributed specifically to sei whales enables historic acoustic records to be re-evaluated for the presence of this species throughout its range.

Anthropogenic noise masking diminishes house wren (Troglodytes aedon) song transmission in urban natural areas

ABSTRACT Anthropogenic noise changes the acoustic environment in which avian signals have evolved, possibly decreasing active space or the area over which signals may be detected and discriminated by receivers. Linking signal transmission patterns to signal function and species’ spatial ecology is important for understanding behavioural changes of receivers in noise. We tested whether varying levels of ambient noise affects transmission of two structurally distinct sections of male house wren (Troglodytes aedon) song used for short- and long-distance communication. We placed our experiment in an ecological context by measuring signal degradation and attenuation in relation to species-typical spacing patterns to investigate whether song structure is maintained within (short-distance within-pair communication) and between territories (long-distance male-male and extra-pair communication) depending on noise levels. Songs experienced more masking and fell below thresholds for detection and discrimination at shorter distances under noisier conditions. Decay of signal-to-noise ratios and cross-correlation factors in noise were so pronounced that song components used for both short- and long-distance communication did not transmit beyond average territory boundaries. Noise masking could affect species ecology: if signals are not detected by intended receivers in noisier habitats, settlement, space use and social interactions may be fundamentally altered compared to those in quieter environments.