Song Variation Research Articles

Is female mate choice repeatable across males with nearly identical songs?

Individual-specific mate preferences are thought to be widespread, but they are still poorly understood in terms of mechanisms and function. Earlier work on a songbird (the zebra finch, Taeniopygia guttata ) showed predominantly individual-specific mate preferences and signs of behavioural incompatibility with certain partners. However, the phenotypic target of preference or aversion remains unclear. A previous study suggested that female preferences may be related to variation in male song. Male zebra finches have individually distinct songs and together with individual-specific female song preferences they could function according to a ‘key–lock principle’. Here we report on a preregistered study in which we tested the hypothesis that individual females respond to males with highly similar songs in a similar way. We selected 18 duos of males with nearly identical songs and released them with females in communal breeding aviaries. We scored female preference as the female's responsiveness to male courtship and confirmed that females indeed had strong individual-specific mate preferences. However, female responsiveness scores were not positively correlated across males closely matched for their song, thereby rejecting the idea of a song-based ‘key–lock principle’ as an explanation for the observed individual-specific preferences. We suggest researchers should focus on details of the interactions between potential partners to elucidate the cause of behavioural incompatibility. • Individual-specific mate preferences are common but poorly understood. • Mate preferences differ strongly between individual female zebra finches. • Individual males differ strikingly in their songs. • Females respond differently to males with exceptionally similar songs. • Song traits are hence not the target of individual-specific preferences.

Song varies with latitude, climate, and species richness in a Neotropical bird

AbstractAnimals can encode information within acoustic signals, particularly, bird songs can be remarkably complex and can indicate individual identity and quality. Two main sets of hypotheses attempt to explain the evolution of increased birdsong complexity across large-scale geographic ranges: 1) larger acoustic space availability, and 2) greater sexual selection intensity, both of which would favor the evolution of more complex songs at higher latitudes, more seasonal and/or species-poor environments. However, few studies have assessed patterns of song complexity for birds with broad geographic ranges. Here, we determined patterns of song variation in the blue-black grassquit (Volatinia jacarina), considering metrics of song complexity, structure and performance. This Neotropical bird occurs from Mexico to Argentina and produces a monosyllabic song. Using recordings from online databases, we calculated song metrics, such as bandwidth, song rate, number of song components, and proportion of vibratos of this signal. We found that song features varied with latitude, climate seasonality, bird species richness, and hemisphere. However, contrary to theoretical predictions, complexity mostly decreased with latitude and greater seasonality, while it was positively correlated with bird species richness. Proportion of vibratos was positively correlated with latitude and seasonality, and may be a feature under sexual selection in this species. Overall, our results did not support the main hypotheses proposed as explanations for song complexity. Our findings also highlight that song complexity does not vary uniformly among songbirds and song parameters, and future studies encompassing more species should clarify patterns and drivers of song variation across broad geographic dimensions.

Individuality, as well as genetic background, affects syntactical features of courtship songs in male mice

Courtship songs in mice have been investigated to understand the mechanisms and ecological relevance of vocal communication. There is evidence that courtship song characteristics vary between individuals from different genetic backgrounds, but little is known about whether individuals, even within the same strain, differ consistently from each other in the syntactical composition and complexity of their songs. In a first confirmatory experiment, we aimed to systematically identify syntactical features typical of songs from different mouse strains, by assessing the composition and complexity (i.e. entropy) of the syntax (i.e. how the different syllables are organized within a song) of male laboratory mice from four different strains ( Mus musculus f. domestica : C57BL/6J, BALB/c, DBA/2 and B6D2F1). Mice were individually presented with a swab containing fresh female urine for 5 min to elicit courtship songs. The four strains differed not only in the composition but also in the complexity of their syntax. In a second experiment, we investigated repeatability over time as a marker of individuality as well as the occurrence of recurring motifs (i.e. identical sets of syllables that are repeated within a song) of BALB/c and DBA/2 mice. The same procedure as in the first experiment was followed, but in addition testing was repeated weekly over 3 weeks. In both strains, most syllable types showed moderate to high repeatability, indicating individuality in song syntax. However, a descriptive hierarchical cluster analysis indicated remarkable variability in how similar the syntaxes of songs from the same individual were over time. Furthermore, individuals varied in the expression of recurring motifs. Our study shows that not only the genetic background but also individuality can affect variability in courtship songs in mice. Together, these findings raise intriguing questions on whether different individual singing strategies exist during courtship. • Courtship songs in mice can serve as a model to study vocal communication. • We assess how strain and individuality affect syntax of courtship songs. • Strains differ in composition and also in complexity of song sequences. • Most syntactical features are repeatable over time, indicative of individuality. • Individuality may partly explain the variation in courtship songs.

Female bird song rates do not covary with population density in a North American species

AbstractBird song can vary across space and time or within different social environments. These variations in bird song have historically been considered from the perspective of males, particularly in North American temperate regions. In this study, we explored possible changes in singing behavior by females of a North American species, the canyon wren (Catherpes mexicanus). Male and female canyon wrens sing sex‐specific songs to defend resources. Females rarely sing spontaneously but sing readily when challenged with playback. We sought to determine whether the rarity of spontaneous female song seen in previous studies stems from low population density. In areas with higher population density, female canyon wrens should encounter neighbors and competitors for resources more often, potentially driving up song rates. We examined female song rates both within a single population and compared between two populations, hypothesizing that females with closer neighbors would (1) sing more often without playback and (2) sing with more aggressive features in their songs and behave more aggressively in response to playback. We estimated population density on the ground using nearest‐neighbor distances and verified these with eBird abundance models. We did not find that population density predicted rates of spontaneous song. Most song characters and playback response behaviors also did not vary with local canyon wren abundance. Females from our denser population sang with significantly lower pitch, but we attribute these differences mostly to geographic variation. Although population density is known to drive patterns and rates of male song behavior, it may be less important in determining female song behavior.

Seasonality and social factors, but not noise pollution, influence the song characteristics of two leaf warbler species.

Changes in the acoustic signalling of animals occupying urban ecosystems is often associated with the masking effects of noise pollution, but the way in which they respond to noise pollution is not straightforward. An increasing number of studies indicate that responses can be case specific, and some species have been found to respond differently to high levels of natural versus anthropogenic noise, as well as different levels of the latter. While the perception of noise between species may vary with its source, amplitude and temporal features, some species may possess broader environmental tolerance to noise pollution, as they use higher frequency vocalizations that are less masked by low-frequency urban noise. In this study, we explored the song variation of two closely related leaf warblers, the Common Chiffchaff Phylloscopus collybita and the Willow Warbler Phylloscopus trochilus, inhabiting urban green spaces and nonurban forests. The main goal of our study was to evaluate the impact of moderate levels of noise pollution on the songs of species which use higher frequency vocalizations and large frequency bandwidth. Previous studies found that the Common Chiffchaff modified their song in response to intense noise pollution, while no such data is available for the Willow Warbler. However, the majority of urban green spaces, which serve as wildlife hot spots in urban environments are usually polluted with moderate noise levels, which may not mask the acoustic signals of species that communicate with higher frequency. We analysed the spectral and temporal song parameters of both warblers and described the ambient noise present in males’ territories. Additionally, we looked at the social and seasonal aspects of bird song, since there is more than just noise in urban ecosystems which may affect acoustic communication. We found no evidence for noise-related bird song divergence in either species, however, we showed that social factors, time of day and season influence certain Common Chiffchaff and Willow Warbler song characteristics. Lack of noise-related bird song divergence may be due to the relatively low variation in its amplitude or other noise features present within the song frequency range of the studied species. Similar results have previously been shown for a few songbird species inhabiting urban ecosystems. Although in many cases such results remain in the shadow of the positive ones, they all contribute to a better understanding of animal communication in urban ecosystems.

Song type variations of Louisiana Waterthrush (Parkesia motacilla) and their geographic distributions.

Louisiana Waterthrush (Parkesia motacilla) is a familiar singer in the Western Hemisphere family Parulidae, yet apparent geographic variations in its song and potentially related causal mechanisms have not received detailed examination in previously published studies. Here, we analyzed song pattern variations of 651 Louisiana Waterthrush singers in audio spectrogram recordings obtained from our field work and publicly accessible bioacoustics archives. Visual and auditory assessment of the introductory note sequence of each song identified three distinct song types (A, B, and C) and most of the songs were assigned to one of these types. Linear Discriminant Analysis and Random Forest methods were used to verify the assignments and showed strong agreement for Type A with slightly less agreement on Types B and C. User error rates (proportion of the Linear Discriminant Analysis classifications that were incorrect) were low for Types A and B, and somewhat higher for Type C, while producer error rates (proportion of the song type for which the Linear Discriminant Analysis was incorrect) were somewhat higher for Types A and C than the minimal levels achieved for Type B. Our findings confirmed that most between-individual variation was in the number of notes and note sequence duration while most within-individual variation resulted from the percent of downstrokes. The location of each singer was plotted on a map of the breeding range and results suggested the song types have large-scale discrete geographic distributions that co-occur in some regions but not range-wide. Evaluation of the distributions provided tentative support for a hypothesis that two of the song types may independently exhibit congruence with the geographic extent of Pleistocene glacial boundaries and the third song type may be distinguished by a lack of congruence, but further investigation is needed to elucidate whether the song variations represent subpopulations with three separate evolutionary histories.

Unilateral vocal nerve resection alters neurogenesis in the avian song system in a region-specific manner.

New neurons born in the adult brain undergo a critical period soon after migration to their site of incorporation. During this time, the behavior of the animal may influence the survival or culling of these cells. In the songbird song system, earlier work suggested that adult-born neurons may be retained in the song motor pathway nucleus HVC with respect to motor progression toward a target song during juvenile song learning, seasonal song restructuring, and experimentally manipulated song variability. However, it is not known whether the quality of song per se, without progressive improvement, may also influence new neuron survival. To test this idea, we experimentally altered song acoustic structure by unilateral denervation of the syrinx, causing a poor quality song. We found no effect of aberrant song on numbers of new neurons in HVC, suggesting that song quality does not influence new neuron culling in this region. However, aberrant song resulted in the loss of left-side dominance in new neurons in the auditory region caudomedial nidopallium (NCM), and a bilateral decrease in new neurons in the basal ganglia nucleus Area X. Thus new neuron culling may be influenced by behavioral feedback in accordance with the function of new neurons within that region. We propose that studying the effects of singing behaviors on new neurons across multiple brain regions that differentially subserve singing may give rise to general rules underlying the regulation of new neuron survival across taxa and brain regions more broadly.

Contrasting patterns of geographical song variation in two closely related passerine species with a simple song

Contrasting patterns of geographical song variation in two closely related passerine species with a simple song

Song variation of a native songbird in a modified habitat by invasive plant.

Habitat structure has been considered as an important factor affecting the acoustic evolution of birds, and bird songs are increasingly affected by artificial environmental variation. Invasive plants sometimes can dramatically alter native habitats, but the song variation of native songbirds migrating into invaded habitats has received little attention. The invasion of smooth cordgrass Spartina alterniflora in the coastal wetlands of eastern China has drastically altered the vegetation structure and some small passerines have begun to use invaded habitats to breed. In this study, we compared the song type prevalence and the song characteristics of male plain prinia Prinia inornata to identify differences in vocal behavior between native and invaded habitats. We also tested for differences in vocal behavior in relation to singing perch and wind speed variation between different habitats. The results indicated that males of plain prinia in invaded habitats sang shorter songs than those in native habitats and had a lower song diversity. The homogeneous vegetation structure and higher wind speed in invaded habitats likely leads to males changing the traditional perched singing style. The song variation may be related to the founder effect, the alteration of vegetation structure and microclimate in invaded habitats. This finding highlights the need for better understanding the behavioral evolution of native species in the process of adapting to the invaded habitat. In the future, experimental manipulation is needed to ascertain how the invasive plant drove these vocal behavior changes of native songbirds.

Ionizing radiation alters male Acheta domesticus courtship songs that are critical for mating success

The impact of ionizing radiation on overall ecosystem health has become a topic of great interest in recent years due to both several nuclear disasters as well as the growing concern over the normal operating waste associated with nuclear power sites. Here, we aimed to analyse how radiation impacts essential characteristics of invertebrate sexual communication including acoustic signalling and the subsequent impacts to mating success. Specifically, we looked at adult male crickets ( Acheta domesticus ) courtship songs, which are vital for this species’ successful reproduction. We analysed the spectral and temporal patterns of nonirradiated and irradiated male songs (0–12 Gy at the fourth instar) as well as several mating parameters to determine possible impacts of song variation on male mating success. Results indicate alterations of several song parameters in irradiated males, with most variation occurring in low-frequency trills: peak and mean frequency, length of pulse and average entropy were significantly altered in doses 7 Gy and above. Mating success at these doses (7 Gy, 10 Gy, 12 Gy) was consequently significantly impacted, with other mating parameters being only significantly altered at the highest radiation doses. Declines in mating parameters were evident at lower doses but were not significant. Here we show that radiation exposure in early stages of development can result in detrimental impacts to vital components of male acoustic signalling, which may be a key or contributing factor to the evident reduction in the ability of males to mate successfully. These impacts are also vital in understanding the potential impact of radiation contamination sites where populations are being chronically exposed over many generations. • Courtship songs were altered by ionizing radiation in crickets ( A. domesticus ). • Male mating success was reduced in irradiated males. • Altered acoustic signalling is a likely cause of mating success decline in crickets.

What is Known-and not Known-About Acoustic Communication in an Urban Soundscape.

Urban environments have some of the most highly modified soundscapes on the planet, affecting the way many animals communicate using acoustic signals. Communication involves transmission of information via signals, such as bird song, between a signaler and a receiver. Much work has focused on the effects of urbanization on signalers and their signals, yet very little is known about how noise pollution affects receiver behaviors and sensory systems. Here, we synthesize key findings to date regarding avian acoustic communication in the urban environment and delineate key gaps in knowledge for future work. We leverage our own work comparing current and historical songs from urban and rural habitats for a subspecies of white-crowned sparrows (Zonotrichia leucophrys nuttalli). We use this system, along with findings from other systems, to answer three key questions in the field: (1) Is song variation consistent with temporal and spatial variation in anthropogenic noise? (2) How are birds adjusting their song to the urban environment? (3) How does song 'urbanization' affect signal function? Our synthesis illustrates that the adjustments birds make to their songs in noisy environments can improve signal detection, but potentially at the cost of signal function. Many key gaps in knowledge need to be addressed to complete our understanding of how acoustic communication systems evolve in urban areas, specifically in regard to sexual selection and female preference, as well as how receivers perceive signals in an urban environment.

Cytonuclear discordance in the crowned-sparrows, Zonotrichia atricapilla and Zonotrichia leucophrys

The golden-crowned (Zonotrichia atricapilla) and white-crowned (Z. leucophrys) sparrows have been presented as a compelling case for rapid speciation. They display divergence in song and plumage with overlap in their breeding ranges implying reproductive isolation, but have almost identical mitochondrial genomes. Previous research proposed hybridization and subsequent mitochondrial introgression as an alternate explanation, but lacked robust nuclear gene trees to distinguish between introgression and incomplete lineage sorting. We test for signatures of these processes between Z. atricapilla and Z. leucophrys, and investigate the relationships among Z. leucophrys subspecies, using mitochondrial sequencing and a reduced representation nuclear genomic dataset. Contrary to the paraphyly evident in mitochondrial gene trees, we confirmed the reciprocal monophyly of Z. atricapilla and Z. leucophrys using large panels of single nucleotide polymorphisms (SNPs). The pattern of cytonuclear discordance is consistent with limited, historical hybridization and mitochondrial introgression, rather than a recent origin and incomplete lineage sorting between recent sister species. We found evidence of nuclear phylogeographic structure within Z. leucophrys with two distinct clades. Altogether, our results indicate deeper divergences between Z. atricapilla and Z. leucophrys than inferred using mitochondrial markers. Our results demonstrate the limitations of relying solely on mitochondrial DNA for taxonomy, and raise questions about the possibility of selection on the mitochondrial genome during temperature oscillations (e.g. during the Pleistocene). Historical mitochondrial introgression facilitated by past environmental changes could cause erroneous dating of lineage splitting in other taxa when based on mitochondrial DNA alone.

Plasticity of stereotyped birdsong driven by chronic manipulation of cortical-basal ganglia activity

Cortical-basal ganglia (CBG) circuits are critical for motor learning and performance, and are a major site of pathology. In songbirds, a CBG circuit regulates moment-by-moment variability in song and also enables song plasticity. Studies have shown that variable burst firing in LMAN, the output nucleus of this CBG circuit, actively drives acute song variability, but whether and how LMAN drives long-lasting changes in song remains unclear. Here, we ask whether chronic pharmacological augmentation of LMAN bursting is sufficient to drive plasticity in birds singing stereotyped songs. We show that altered LMAN activity drives cumulative changes in acoustic structure, timing, and sequencing over multiple days, and induces repetitions and silent pauses reminiscent of human stuttering. Changes persisted when LMAN was subsequently inactivated, indicating plasticity in song motor regions. Following cessation of pharmacological treatment, acoustic features and song sequence gradually recovered to their baseline values over a period of days to weeks. Together, our findings show that augmented bursting in CBG circuitry drives plasticity in well-learned motor skills, and may inform treatments for basal ganglia movement disorders.

A desert songbird with no confamilials in the Western Hemisphere (Verdin,Auriparus flaviceps) investigates divergent conspecific songs

AbstractMost birds that show geographic variation in their songs discriminate between local and foreign songs, which may help them avoid unnecessary conflicts with vagrant individuals or similar-sounding congeners. However, some species respond equally to foreign and local songs, which may be useful if foreign individuals present territorial threats or if there are no sympatric congeners to avoid. Species without sympatric congeners are not commonly tested in playback studies, but they offer an opportunity to see how song variation and recognition unfolds when the pressure to avoid similar congeners is absent. Here, we use Verdins (Auriparus flaviceps), a monotypic genus of songbird with no confamilials in North America, to explore song variation and recognition in a species living without close relatives. We assessed geographic variation in song across the Verdin range and conducted a playback experiment using exemplars from 2 acoustically divergent and geographically distant regions as treatments. We found significant geographic variation in song that mapped well onto ecologically distinct desert regions. We found that Verdins had stronger vocal responses to local-sounding songs, but had equal movement responses to local-sounding and foreign songs. These results are similar to results found in other species without sympatric congeners and provide an example of a species that investigates acoustically divergent conspecific songs, despite recognizing salient differences in those songs.

First description of the structure and geographic patterns in the songs of the Connecticut Warbler (Oporornis agilis)

Geographic variation in song characteristics within songbird species has the potential to reveal some of the complex interactions between ecology and behavior. The Connecticut Warbler (Oporornis agilis) is an uncommon and little studied Neotropical migratory wood warbler that breeds across the southern boreal forest in North America. The song of the Connecticut Warbler has remained poorly described and, prior to our study, no detailed spectrographic analysis exists. We document 20 distinct song variants in this species, based on differences in the structure and sequence of notes within repeated phrases, from across the breeding range. One song type, distributed across the entire breeding range, represented 36% of our samples. Preliminary evidence suggests a lack of geographic structure and no evidence of dialects or regiolects in the song types of this species. Our results highlight a unique distribution in song types within the Oporornis–Geothlypis complex, providing a baseline for future studies of geographic variation in this, and related, species.

Noise-Related Song Variation Affects Communication: Bananaquits Adjust Vocally to Playback of Elaborate or Simple Songs

Birds communicate through acoustic variation in their songs for territorial defense and mate attraction. Noisy urban conditions often induce vocal changes that can alleviate masking problems, but that may also affect signal value. We investigated this potential for a functional compromise in a neotropical songbird: the bananaquit (Coereba flaveola). This species occurs in urban environments with variable traffic noise levels and was previously found to reduce song elaboration in concert with a noise-dependent reduction in song frequency bandwidth. Singing higher and in a narrower bandwidth may make their songs more audible in noisy conditions of low-frequency traffic. However, it was unknown whether the associated decrease in syllable diversity affected their communication. Here we show that bananaquits responded differently to experimental playback of elaborate vs. simple songs. The variation in syllable diversity did not affect general response strength, but the tested birds gave acoustically distinct song replies. Songs had fewer syllables and were lower in frequency and of wider bandwidth when individuals responded to elaborate songs compared to simple songs. This result suggests that noise-dependent vocal restrictions may change the signal value of songs and compromise their communicative function. It remains to be investigated whether there are consequences for individual fitness and how such effects may alter the diversity and density of the avian community in noisy cities.

Genomic and acoustic differences separate Lilian’s Meadowlark (Sturnella magna lilianae) from Eastern (S. magna) and Western (S. neglecta) meadowlarks

AbstractExamining differences among recently diverged populations can provide insight into the traits and evolutionary mechanisms that drive or maintain divergence. The genus Sturnella includes 2 recently diverged species, Sturnella magna (Eastern Meadowlark) and S. neglecta (Western Meadowlark), the former of which has a complex of subspecies distributed across the Americas. Of the S. magna subspecies that occur in the United States, S. m. lilianae is the only one with a disjunct range, occurring in the southwestern United States and central Mexico. It also has markedly different song patterns than all other S. magna subspecies. In order to assess population differentiation, we performed whole-genome sequencing of 35 birds and analyzed song characteristics from 85 birds. Songs from each species and S. m. lilianae were diagnosable using linear discriminant function analysis and support divergence in song between all taxa. Phylogenetic analysis and admixture proportions support 3 distinct clades within North American meadowlarks, and tests of introgression failed to detect a significant signal. Overall, our results indicate that S. m. lilianae exhibits high levels of genetic and vocal differentiation from both S. magna and S. neglecta, with no evidence of introgression between any group, and forms a distinct evolutionary lineage. We thus recommend the elevation of S. m. lilianae to species status.

Reproductive Character Displacement Drives Diversification of Male Courtship Songs in Drosophila.

AbstractMale secondary sexual traits are one of the most striking and diverse features of the animal kingdom. While these traits are often thought to evolve via sexual selection, many questions remain about their patterns of diversification and their role in speciation. To address these questions, I performed a comparative study of precopulatory male courtship songs of 119 Drosophila species across 10 distinct species groups. I related song divergence to genetic distances, geographic relationships, and sexual isolation between species. On the basis of pairwise Euclidean song distances, species groups typically retained their phylogenetic signal while species within groups diverged five times more in sympatry relative to allopatry, producing a pattern of reproductive character displacement. This occurred despite similar genetic distances in allopatry and sympatry, was exaggerated among younger species pairs, and was driven primarily by the parameter interpulse interval. While sexual isolation in sympatry was high even with low song divergence, these variables were correlated with each other and with increased divergence of female mating preferences in sympatry. The widespread pattern of character displacement implies that allopatric divergence due to processes like sexual selection are very slow relative to sympatric processes such as reinforcement and reproductive interference in driving song diversification across Drosophila.

Song divergence indicates an unclear relationship between the Neotropical and Nearctic Horned Larks

BackgroundSome studies have indicated that the Horned Larks (Eremophila alpestris) should be considered as a species complex. Recently it split into four species or clades and seven subclades based on genetic, morphological, and biogeographic data. However, other aspects like song divergence have not been studied and several subspecies have not been evaluated, leading to important information gaps in this group of birds. In this work, we aimed to assess the differences in song traits and playback response between the Nearctic subclade and the Neotropical or Colombian subspecies E. a. peregrina.MethodsWe compared six song traits between these groups and performed field playback experiments, to test the response of the Neotropical larks to both songs. We tested the difference in the variables for separate as well as by principal component analysis (PCA).ResultsWe found significant differences (p < 0.05) in the individual song traits and the PCA analysis between the two groups. Further, the PCA analysis showed a clearer divergence of the Neotropical songs in comparison to the Nearctic songs of different locations within North America. Similarly, the playback analysis showed a significantly lower response of E. a. peregrina to the songs of the Nearctic larks.ConclusionsBesides this song divergence, there are important ecological and biogeographic differences between the Neotropical and Nearctic Horned Larks, that indicate an unclear relationship between these two groups. Thus, further morphological and genetic studies are required to clarify the taxonomy of the Neotropical Horned Lark and define if they share the same evolutionary history as the other subspecies of the Nearctic subclade.

Singing in a fragmented landscape: wrens in a tropical dry forest show sex differences in the effects of neighbours, time of day, and time of year

Songbird vocalizations serve diverse functions including territory defence against neighbouring conspecific animals. In tropical and south-temperate regions, it is commonplace for both female and male songbirds to sing solo songs and coordinated vocal duets to defend their territories. The Area de Conservacion Guanacaste in Costa Rica is the site of an ambitious conservation effort to protect and regrow tropical dry forests; it consists of a mosaic of regenerating and mature forest patches, presenting a special opportunity to study the effect of different numbers of neighbours on male and female wrens living in these fragmented forests. We analyzed recordings of Rufous-and-white Wrens (Thryophilus rufalbus) over a 17-year period, focusing on vocal behaviour and variation in the number of territorial neighbours within the fragmented landscape in the conservation area, and on diel and seasonal variation in female and male song. We hypothesized that the number of conspecific neighbours would influence vocal behaviours, including female and male solo song rate, duet responsiveness rate, repertoire use, and song-switching rate. For females, we found that wrens change song-types more often in areas with more neighbours, whereas the other aspects of female vocal behaviour did not vary with the number of neighbours. For males, we found no aspect of vocal behaviour that varied with the number of neighbours. For both sexes, we found variation in vocal behaviours with time of day and time of year, in keeping with previous research. Our results underscore the idea that we must explore female and male birds independently, because the sexes may respond differently to external factors. We did not find strong links between wren vocal behaviour and variation in the number of neighbours, yet we encourage further behavioural studies on vocal behaviour of birds with varying numbers of neighbours in fragmented landscapes.