Song Variation Research Articles

Rapid speciation via the evolution of pre-mating isolation in the Iberá Seedeater.

Behavioral isolation can catalyze speciation and permit the slow accumulation of additional reproductive barriers between co-occurring organisms. We illustrate how this process occurs by examining the genomic and behavioral bases of pre-mating isolation between two bird species (Sporophila hypoxantha and the recently discovered S. iberaensis) that belong to the southern capuchino seedeaters, a recent, rapid radiation characterized by variation in male plumage coloration and song. Although these two species co-occur without obvious ecological barriers to reproduction, we document behaviors indicating species recognition by song and plumage traits and strong assortative mating associated with genomic regions underlying male plumage patterning. Plumage differentiation likely originated through the reassembly of standing genetic variation, indicating how novel sexual signals may quickly arise and maintain species boundaries.

Ecological and evolutionary drivers of geographic variation in songs of a Neotropical suboscine bird: The Drab-breasted Bamboo Tyrant (Hemitriccus diops, Rhynchocyclidae)

Abstract Understanding the evolutionary and ecological mechanisms that shape the spatial divergence of signals involved in reproductive isolation is a central goal in studies of speciation. For birds with innate songs, such as the suboscine passerine birds, the integration and comparison of both genetic and ecological factors in explaining song variation at the microevolutionary scale are rare. Here, we evaluated the evolutionary and ecological processes underlying the variation in the songs of the Atlantic Forest endemic Drab-breasted Bamboo Tyrant (Hemitriccus diops), testing the effects of both stochastic and adaptive processes, namely the stochastic and acoustic adaptation hypotheses, respectively. We combined vocal, genetic, and ecological (climate and forest cover) data across the species’ range. To this end, we analyzed 89 samples of long and short songs. We performed analyses on raw and synthetic data song variables with linear mixed models and multivariate statistics. Our results show that both song types differ in spectral features between the 2 extant phylogeographic lineages of this species, but such vocal divergence is weak and subtle in both song types. Overall, there is a positive relationship of acoustic distances with the amount of forest cover in long songs. Our results suggest that there is cryptic geographical variation in both song types and that this variation is associated with low levels of genetic divergence in both songs and with ecological factors in long songs.

Song variation between sexes and among subspecies of New Zealand Fantail (Rhipidura fuliginosa)

ABSTRACT Variation in bird song occurs at many levels, including between sexes and among geographic regions. Variation can be due to differences in function, habitat, selection or drift. Quantifying when and where such differences occur provides insight into which of these drivers is most likely. Here we examine song variation, (a) between sexes and (b) among the three geographically isolated subspecies, of the New Zealand Fantail (Rhipidura fuliginosa), a monomorphic passerine native to New Zealand. We measured twelve temporal and frequency parameters from recorded songs based on buzz notes. Only maximum frequency in one of the three phrases showed a significant sex difference, although there were suggestions of other sex differences in some element-level parameters. Song characteristics differed notably among subspecies; North Island Fantails typically produced shorter songs, comprised shorter elements at higher frequencies and faster element rates, while the most isolated birds (Chatham Island population), sang longer, slower songs. South Island birds were intermediate and more variable. The similarity of male and female songs suggests song is used by both sexes for similar purposes, while selection pressures associated with different habitats or cultural drift may be responsible for the song differences observed among sub-species. Further research analysing vocalisations of both sexes across a broader geographical range is required to further our understanding of female song function and patterns of geographic variation.

Revitalization of dadong dauh balinese children’s illustrated song into 2-dimensional animation as an educational tourism strategy

This study produced animated video clips revived from Balinese children’s song as an alternative media, by promoting brand equity in the form of characters and popular tourist attractions as an effort to promote cultural tourism in Bali, Indonesia. The strategy in reviving children’s songs was done through revitalizing the visualization of Balinese children’s illustrated songs. The visualization was done by turning the previous appearance of live action appearance into an animated form that proved to be preferred by children. The design of the Dadong Dauh character was constructed by manga matrix system model approach introduced by Tsukamoto. The data collection about song variation of Dadong Dauh and theory to develop imagery character and to design the character by using the manga matrix system was used by conducting a literature study. Reference collection of the visual of Dadong Dauh was used by conducting a literature study and observation. The result showed that the visualized video clip of local Balinese children songs in a two-dimensional form was able to revitalize the character branding of Dadong Dauh as a cultural symbol, with Tenganan village as its cultured environment. It also gained a great appreciation from children and has potential to popularize Dadong Dauh song.

Asymmetric behavioural responses to divergent vocal signals in allopatric Neotropical sparrows

Birdsongs are signals that encode information for multiple behaviours such as species recognition. Species recognition is influenced by both geographical variation in song and birds' discrimination abilities, forming the basis for evolutionary processes driving reproductive isolation and speciation. Here, we assessed the behavioural responses to geographical variation in songs in olive sparrows, Arremonops rufivirgatus . We conducted a series of playback experiments in two allopatric populations (Pacific, Peninsula) to assess whether olive sparrows responded differentially to geographical variants of their song and whether such responses could be predicted by the acoustic similarity between subject and stimulus songs. Our results indicate an asymmetrical behavioural response, with the Pacific population responding strongly to both local and allopatric stimuli and weakly to the control, and the Peninsula population responding strongly to local stimuli and weakly to both allopatric stimuli and the control. Furthermore, despite the birds' lack of previous experience with the playback stimulus songs, we found that response intensity was predicted by the acoustic similarity in both populations, with stronger responses to more similar songs, suggesting that males from different population may use a similar mechanism to recognize signals, despite whether the signal comes from conspecifics or heterospecifics. Our findings support the hypothesis that song divergence could act as a premating barrier for at least one of the studies populations, and that birds' responses are dictated by the structural similarity between senders' and receivers’ signals. • Isolated populations evolved differential perception abilities. • Males from different populations respond with different signals (vocal vs physical). • Behavioural response intensity is associated with song acoustic similitude. • Males recognize potential competitors using structural characteristics of the songs.

Differential geographic patterns in song components of male Albert's lyrebirds.

Geographic variation in bird song has received much attention in evolutionary studies, yet few consider components within songs that may be subject to different constraints and follow different evolutionary trajectories. Here, we quantify patterns of geographic variation in the socially transmitted “whistle” song of Albert's lyrebirds (Menura alberti), an oscine passerine renowned for its remarkable vocal abilities. Albert's lyrebirds are confined to narrow stretches of suitable habitat in Australia, allowing us to map likely paths of cultural transmission using a species distribution model and least cost paths. We use quantitative methods to divide the songs into three components present in all study populations: the introductory elements, the song body, and the final element. We compare geographic separation between populations with variation in these components as well as the full song. All populations were distinguishable by song, and songs varied according to the geographic distance between populations. However, within songs, only the introductory elements and song body could be used to distinguish among populations. The song body and final element changed with distance, but the introductory elements varied independently of geographic separation. These differing geographic patterns of within‐song variation are unexpected, given that the whistle song components are always produced in the same sequence and may be perceived as a temporally discrete unit. Knowledge of such spatial patterns of within‐song variation enables further work to determine possible selective pressures and constraints acting on each song component and provides spatially explicit targets for preserving cultural diversity. As such, our study highlights the importance for science and conservation of investigating spatial patterns within seemingly discrete behavioral traits at multiple levels of organization.

Similarities in composition and transformations of songs by humpback whales (Megaptera novaeangliae) over time and space.

The complex songs produced by humpback whales have been cited as evidence of prodigious memory, innovativeness, sophisticated auditory scene analysis, vocal imitation, and even culture. Researchers believe humpbacks learn their songs culturally because songs appear to change rapidly, consistently, and irreversibly across whales within a population. Here, we present evidence of similarities in song structure both across populations and decades that strongly challenge claims that social learning is the main driver of variations in humpback whale songs over time. Groups of humpback whales that were not in acoustic contact (recorded in Puerto Rico in 1970, Hawaii in 2012, and Colombia in 2013-2019) produced songs in acoustically comparable cycles, suggesting that progression through sound patterns within and across songs is not simply determined by vocal imitation of innovative patterns, but may instead be controlled by production templates that prescribe how singers construct and transform songs over time. Identifying universal constraints on song production is critical to evaluating the role of vocal imitation and cultural transmission in the progressive changes that humpback whales make to their songs and for evaluating the functional relevance of such changes. The current findings illustrate how information theoretic analyses of vocal sequences can potentially obscure key acoustic qualities of signals that may be critical to understanding how vocalizers produce, perceive, and use those sequences. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

A new look at universals and specificities in the songs of humpback whales.

In this issue's featured article, Mercado and Perazio (2021) describe songs of humpback whales using acoustic qualities, in part to determine the degree of similarity in songs across time and space that have not been revealed by information-theoretic analyses. They are particularly interested in evaluating alternative explanations of song variations in humpback whales. They argue that if humpback whales' songs "are . . . transmitted through acoustic contact followed by imitation" (p. 29) then (a) songs of populations not in acoustic contact should diverge, (b) songs of the same population should diverge increasingly over time, and (c) song forms separated by multiple decades either within or across populations should be dissimilar. Alternatively, acoustic similarities in song structure across populations and/or across decades in the same population would challenge the hypothesis that socially mediated learning is the primary driver of variation in the structure of humpback whales' songs over time. If that is the case, then identifying universal properties of song composition is important to move the field forward. Broadening the analytical tool kit can help in this effort. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Introductory gestures before songbird vocal displays are shaped by learning and biological predispositions.

Numerous animal displays begin with introductory gestures. For example, lizards start their head-bobbing displays with introductory push-ups, and many songbirds begin their vocal displays by repeating introductory notes (INs) before producing their learned song. Among songbirds, the acoustic structure and the number of INs produced before song vary considerably between individuals in a species. While similar variation in songs between individuals is a result of learning, whether variations in INs are also due to learning remains poorly understood. Here, using natural and experimental tutoring with male zebra finches, we show that mean IN number and IN acoustic structure are learned from a tutor. Interestingly, IN properties and how well INs were learned, were not correlated with the accuracy of song imitation and only weakly correlated with some features of songs that followed. Finally, birds artificially tutored with songs lacking INs still repeated vocalizations that resembled INs, before their songs, suggesting biological predispositions in IN production. These results demonstrate that INs, just like song elements, are shaped both by learning and biological predispositions. More generally, our results suggest mechanisms for generating variation in introductory gestures between individuals while still maintaining the species-specific structure of complex displays like birdsong.

Sympatry drives colour and song evolution in wood-warblers (Parulidae).

Closely related species often exhibit similarities in appearance and behaviour, yet when related species exist in sympatry, signals may diverge to enhance species recognition. Prior comparative studies provided mixed support for this hypothesis, but the relationship between sympatry and signal divergence is likely nonlinear. Constraints on signal diversity may limit signal divergence, especially when large numbers of species are sympatric. We tested the effect of sympatric overlap on plumage colour and song divergence in wood-warblers (Parulidae), a speciose group with diverse visual and vocal signals. We also tested how number of sympatric species influences signal divergence. Allopatric species pairs had overall greater plumage and song divergence compared to sympatric species pairs. However, among sympatric species pairs, plumage divergence positively related to the degree of sympatric overlap in males and females, while male song bandwidth and syllable rate divergence negatively related to sympatric overlap. In addition, as the number of species in sympatry increased, average signal divergence among sympatric species decreased, which is likely due to constraints on warbler perceptual space and signal diversity. Our findings reveal that sympatry influences signal evolution in warblers, though not always as predicted, and that number of sympatric species can limit sympatry's influence on signal evolution.

Contribution to unravel variability in bowhead whale songs and better understand its ecological significance

Since the first studies on bowhead whale singing behaviour, song variations have been consistently reported. However, there has been little discussion regarding variability in bowhead whale singing display and its ecological significance. Unlike the better studied humpback whales, bowhead whales do not appear to share songs at population level, but several studies have reported song sharing within clusters of animals. Over the winter season 2013–2014, in an unstudied wintering ground off Northeast Greenland, 13 song groups sharing similar hierarchical structure and units were identified. Unit types were assessed through multidimensional maps, showing well separated clusters corresponding to manually labelled units, and revealing the presence of unit subtypes. Units presented contrasting levels of variability over their acoustic parameters, suggesting that bowhead whales keep consistency in some units while using a continuum in values of frequency, duration and modulation parameters for other unit types. Those findings emphasise the need to account for variability in song analysis to better understand the behavioural ecology of this endangered species. Additionally, shifting from song toward units or phrase-based analysis, as it has been suggested for humpback whales, offers the opportunity to identify and track similarities in songs over temporal and geographical scales relevant to population monitoring.

Retraction: Extraordinary variation in a simple song: No geographical patterns in initial phrase variation of the Yellowhammer, a passerine with pronounced dialects

Retraction: Extraordinary variation in a simple song: No geographical patterns in initial phrase variation of the Yellowhammer, a passerine with pronounced dialects

Geographically distinct blue whale song variants in the Northeast Pacific

The Northeast Pacific (NEP) population of blue whalesBalaenoptera musculus musculusis currently managed as a single stock. We investigated the fine-scale frequency characteristics of 1 NEP blue whale song unit, the B call. We analyzed B calls from passive acoustic data collected between 2010 and 2013 at 2 low-latitude sites, Palmyra Atoll and the Hawaiian Islands, and 3 higher-latitude sites, off southern California, off Washington state and in the Gulf of Alaska. Frequency measurements were extracted along the contour of the third harmonic from each call, and data from each region were compared. Calls from the Gulf of Alaska and Hawai‘i presented a downshift in frequency, beginning just past the midway point of the contour, which was not present in calls recorded from southern California or Palmyra Atoll. Calls from Washington displayed intermediate characteristics between those from the other 2 high-latitude sites. Cluster analysis resulted in consistent grouping of call contours from Washington and southern California, in what we termed the NEP B1 variant, while contours from Hawai‘i and the Gulf of Alaska were grouped together, as a NEP B2 variant. Frequency differences were also observed among the variants; the Gulf of Alaska displayed the highest frequency on average, followed by Washington, then southern California. Consistent with other studies, a yearly decline in the frequency of B calls was also observed. This discovery of at least 2 geographically distinct variants provides the first evidence of vocally distinct subpopulations within the NEP, indicating the possibility of a need for finer-scale population segmentation.

Song parameters, repertoire size and song sharing within and across age classes in the saffron finch

Birds sing mostly to attract partners or to defend territories or resources. In relation to the first function, song can vary with age if older experienced males signal their quality through their vocal output. Regarding the second function, song can also vary with age if singing behavior helps mediate social interactions through repertoire sharing with neighbors. Here, we investigate whether song parameters change with age, and in which direction, in saffron finches Sicalis flaveola pelzelni, obligate secondary cavity nesters which produce elaborate melodious songs and show delayed plumage maturation. Cross‐sectional comparisons revealed that second year (SY) males sing shorter syllables, and shorter and less versatile songs than older after second year males (ASY), as expected if the latter are more experienced singers. Longitudinal comparisons, which better depict age‐related changes, showed that as birds age one year, song length and repertoire size do not change significantly, syllable duration shortens and, as expected for experienced singers, song versatility increases. Correlations between repertoire distance and nesting distance suggest that both SY and ASY males might be adjusting their repertoires to those of ASY neighbors; the former pattern conforms to the expectations if young birds try to emulate the songs of more experienced birds, while the latter is expected if song sharing helps de‐escalating antagonistic social interactions amongst males. This research, which provides the first description of song parameters in young second year saffron finches, expands our knowledge of song variation across age classes in songbirds.

Variable or atypical? Comparing unusual songs of the Tufted Titmouse with a citizen-science database

The Tufted Titmouse Baeolophus bicolor is well known for its stereotyped “peter-peter-peter” song, but anecdotal reports of its song’s diversity also exist. We identified an atypical song in East-Central Illinois, USA, that has persisted for several years in the same vicinity. We used a spectrogram-based comparison metric to assess song similarity scores against con- and heterospecific songs from a citizen-science database. The results suggest that these novel songs may truly be outliers beyond the Tufted Titmouse’s local range of species-typical song variability. Our study also illustrates a methodological approach regarding the assessment of other, potentially atypical vocalizations recorded from birds.

Song learning by prairie warblers: When, where, and from whom

AbstractSongbirds of many species acquire their songs by imitating the songs of conspecific singers. Conclusive evidence of such imitation comes from controlled laboratory studies, but such studies do not reveal when and where songbirds learn their songs under natural conditions. To determine the timing and location of song learning in a population of prairie warblers, we compared the songs of yearling prairie warblers of known hatching location to the songs of other birds in the yearlings' natal and first breeding areas. The comparisons yielded a likely model song (and model singer) for each of the song types used by the focal yearlings. We supplemented our findings from the song comparisons with inferences drawn from an analysis of local geographic variation in songs. This analysis revealed that shared song types showed no tendency to be geographically clustered within the study area. Taken together, our data suggest that prairie warblers learn their songs during the hatch year, at locations somewhat distant (mean distance 1,437 m) from their natal site, most likely as birds wander about during the post‐fledging period.

Relationships among song characteristics in Japanese tits

Birdsongs often contain two simultaneous, harmonically unrelated sounds; however, little is known of the function of this two-voice phenomenon. We hypothesized that it contributes to increases in song speed and note repertoire, which are important song characteristics in sexual selection. We analyzed six song variables in Japanese tits (Parus minor) and found positive correlations between all possible pairs of the proportion in length of two-voice vocalization, note rate, and note type repertoire, which is consistent with our hypothesis. This finding is a first step towards determining the function of two-voice vocalization in song communication.

Continent-wide Shifts in Song Dialects of White-Throated Sparrows

Hypotheses on regional song variation ("dialects") assume that dialects remain stable within regions, are distinct between regions, and persist within populations over extensive periods [1-3]. Theories to explain dialects focus on mechanisms that promote persistence of regional song variants despite gene flow between regions [4-6], such as juveniles settling in non-natal populations retaining only those songs from their repertoires that match neighbors [7, 8]. It would be considered atypical for a novel song variant to invade and replace the established regional variant. Yet some studies have reported song variants shifting rapidly over time within populations [9-11]. White-throated sparrows, Zonotrichia albicolis, for example, traditionally sing a whistled song terminating in a repeated triplet of notes [12], which was the ubiquitous variant in surveys across Canada in the 1960s [13]. However, doublet-ending songs emerged and replaced triplet-ending songs west of the Rocky Mountains sometime between 1960 and 2000 [11] and appeared just east of the Rockies in the 2000s [14]. From recordings collected over two decades across North America, we show that doublet-ending song has now spread at a continental scale. Using geolocator tracking, we confirm that birds from western Canada, where doublet-ending songs originated, overwinter with birds from central Canada, where the song initially spread. This suggests a potential mechanism for spread through song tutoring on wintering grounds. Where the new song variant has spread, it rose from a rare variant to the sole, regional song type, as predicted by the indirect biased transmission hypothesis [10]. VIDEO ABSTRACT.

Wildfires and mass effects of dispersal disrupt the local uniformity of type I songs of Hermit Warblers in California

Abstract Hermit Warblers (Setophaga occidentalis) sing a formulaic, type I song to attract mates, in contrast to a repertoire of more complex, type II songs to defend territories. A single, dominant type I song, or a low diversity of type I songs, often occur within a geographic area. We provide the first comprehensive description of Hermit Warbler type I song variants throughout California, USA. We recorded type I songs from 1,588 males across 101 study sites in the state from April through July 2009–2014. Using those locations and a pre-existing range map of the species, we created a maximum entropy-based breeding habitat suitability map and classified the songs into 35 variants using a typological rubric. We validated consistent classification of songs for 87.5% of the birds. We then modeled the effects of recent fire history at the local scale (10 yr, 315 km2), the amount of breeding habitat at the regional scale (8,000 km2), and the distance between territories to examine factors involved in song sameness at the local scale. We found that the probability of different birds singing the same form declined with the amount of local fire, regional habitat, and distance, and that these findings were robust to uncertainty in our song classification rubric. Using a longitudinal analysis including additional data from 10 study areas revisited in 2019, we showed that song structure within forms had drifted since our initial visits 5–10 yr earlier, and that the evenness (e.g., Simpson’s measure) of song forms increased at locations that had been burned by wildfire between visits. Taken together, the results suggest that wildfires and the mass effects of dispersal of birds singing rival song forms disrupt the uniformity of type I songs locally. The results demonstrate how species traits, such as birdsong, can be used to disentangle the ecological processes that regulate observed patterns in biodiversity. Further investigation is recommended to determine whether song pattern dynamics reflect underlying genetic differences and habitat specializations among subpopulations.

Gaudeamus: from Source of Origin to Cult

. The existing versions of the ancient student song are discussed and the original source of the world-famous hymn is identified in this article. The purpose of the presented work is to isolate and explore the existing variants of the ancient student song, to establish their subordination and authorship, to determine the source of the world-famous hymn. The d iscover ing of the mechanism of creation of the medieval song «Gaudeamus» and its modern reading is t he scientific novelty in this area. T he analysis of the latin text in comparison with the modern interpretation of ancient poetry by scientists of Russia, Germany and Spain was the basis for the study. The maximum objectivity in presenting factual material was found i n th is work. A method of dialogical interpretation of the text, in particular its cultural and historical aspect , was used in order to study the work . Conclusions . The literary and musical part of the texts of the student hymn from the very first printed versions, which are stored in the archives, are analyzed; literary versions of the song are presented and their authorship is determined; the authors of the musical accompaniment have been identified, based on the existing versions of the hymn. The cult of ancient song and its origin, started by the Germans, that became a bestseller in music and became the world hymn of youth, is proved.