Heterospecific Songs Research Articles

Expansion of learning capacity elicited by interspecific hybridization.

Learned behavior, a fundamental adaptive trait in fluctuating environments, is shaped by species-specific constraints. This phenomenon is evident in songbirds, which acquire their species-specific songs through vocal learning. To explore the neurogenetic mechanisms underlying species-specific song learning, we generated F1 hybrid songbirds by crossing Taeniopygia guttata with Aidemosyne modesta. These F1 hybrids demonstrate expanded learning capacities, adeptly mimicking songs from both parental species and other heterospecific songs more extensively than their parental counterparts. Despite the conserved size of brain regions and neuron numbers in the neural circuits for song learning and production, single-cell transcriptomics reveals distinctive transcriptional characteristics in the F1 hybrids, especially in vocal-motor projection neurons. These neurons exhibit enrichment for nonadditively expressed genes, particularly those related to ion channel activity and cell adhesion, which are associated with the degree of song learning among F1 individuals. Our findings provide insights into the emergence of altered learning capabilities through hybridization, linked to cell type-specific transcriptional changes.

Potential social facilitation through song in bird communities

The main function of birdsong is to attract mates and defend territories among conspecifics, but little is known about the potential of this behavior in generating interactions among co-existing bird species that signal at the same time. Different hypotheses have been put forward to explain the mechanisms that govern signaling in crowded acoustic spaces, including competition for acoustic space, interspecific territoriality, environmental filters, and acoustic social facilitation. We tested these hypotheses in a forest bird community by studying the behavioral, acoustic, and ecological characteristics of 13 co-occurring species. We used passive recordings to assess the magnitude and the determinants of heterospecific song co-occurrence (i.e., when different species sing at the same time and place), and playback experiments to quantify the propensity of birds to sing if stimulated by heterospecific songs. Birds more frequently sang with species with dissimilar songs. In the breeding season, they also actively sang after the playback of other species, especially if these had dissimilar songs, and occasionally after non-avian unfamiliar playbacks. Heterospecific songs may trigger song utterance because they indicate a predator-free environment, or reduce predation risk through dilution effects, and these benefits may be maximized if there is little acoustic similarity. In line with ecological theory on community assembly mechanisms, these results are compatible with limiting similarity (species with similar songs sing at different times) and suggests social facilitation between phenotypically dissimilar species. These potential biotic interactions through songs may represent a mechanism that leads to bird species coexistence and are worth exploring at the community level.Significance statementIt is generally assumed that bird species avoid acoustic overlap with birds singing similar songs, but there is also evidence of active interspecific territoriality through song displays between pairs of species. Community-wide responses through songs have never been investigated in birds, and to fill this knowledge gap we performed both observations and experiments on multiple coexisting species. Birds tended to sing with species with more dissimilar songs and they were also actively stimulated to sing when the songs of species with dissimilar songs were played back. An interaction between species with dissimilar songs therefore emerged, potentially yielding anti-predatory benefits. Such active behavior, which would have gone unnoticed if observations only were performed, involves multiple species, and therefore may represent a community-wide mechanism of species coexistence.

Age effects in Darwin’s finches: older males build more concealed nests in areas with more heterospecific singing neighbors

Nesting success tends to increase with age in birds, in part because older birds select more concealed nest sites based on experience and/or an assessment of prevailing predation risk. In general, greater plant diversity is associated with more biodiversity and more vegetation cover. Here, we ask if older Darwin’s finch males nest in areas with greater vegetation cover and if these nest sites also have greater avian species diversity assessed using song. We compared patterns in Darwin’s Small Tree Finch (Camarhynchus parvulus) and Darwin’s Small Ground Finch (Geospiza fuliginosa) as males build the nest in both systems. We measured vegetation cover, nesting height, and con- vs. heterospecific songs per minute at 55 nests (22 C. parvulus, 33 G. fuliginosa). As expected, in both species, older males built nests in areas with more vegetation cover and these nests had less predation. A novel finding is that nests of older males also had more heterospecific singing neighbors. Future research could test whether older males outcompete younger males for access to preferred nest sites that are more concealed and sustain a greater local biodiversity. The findings also raise questions about the ontogenetic and fitness consequences of different acoustical experiences for developing nestlings inside the nest.

Effect of estradiol and predator cues on behavior and brain responses of captive female house sparrows (Passer domesticus).

The presence of predators can cause major changes in animal behavior, but how this interacts with hormonal state and brain activity is poorly understood. We gave female house sparrows (Passer domesticus) in post-molt condition an estradiol (n = 17) or empty implant (n = 16) for 1week. Four weeks after implant removal, a time when female sparrows show large differences in neuronal activity to conspecific vs. heterospecific song, we exposed birds to either 30min of conspecific song or predator calls, and video recorded their behavior. Females were then euthanized, and we examined neuronal activity using the expression of the immediate early gene (IEG) ZENK to identify how the acoustic stimuli affected neuronal activation. We predicted that if female sparrows with estradiol implants reduce neuronal activity in response to predator calls as they do to neutral tones and non-predatory heterospecifics, they would show less fear behavior and a decreased ZENK response in brain regions involved in auditory (e.g., caudomedial mesopallium) and threat perception functions (e.g., medial ventral arcopallium) compared to controls. Conversely, we predicted that if females maintain auditory and/or brain sensitivity towards predator calls, then female sparrows exposed to estradiol would not show any differences in ZENK response regardless of playback type. We found that female sparrows were less active during predator playbacks independent of hormone treatment and spent more time feeding during conspecific playback if they had previously been exposed to estradiol. We observed no effect of hormone or sound treatment on ZENK response in any region of interest. Our results suggest that female songbirds maintain vigilance towards predators even when in breeding condition.

Responses of Yellowhammer Emberiza citrinella, Pine Bunting E. leucocephalos and Their Hybrids to Playbacks of Con- and Heterospecific Songs and Calls in a Hybrid Zone

Responses of Yellowhammer Emberiza citrinella, Pine Bunting E. leucocephalos and Their Hybrids to Playbacks of Con- and Heterospecific Songs and Calls in a Hybrid Zone

Male superb lyrebirds mimic functionally distinct heterospecific vocalizations during different modes of sexual display

Mimicry has long been a focus of research, but little is known about how and why many species of bird incorporate imitations of heterospecific sounds into their vocal displays. Crucial to understanding mimetic song is determining what sounds are mimicked and in what contexts such mimicry is produced. The superb lyrebird, Menura novaehollandiae, is a large oscine passerine with a lek-like mating system. Both sexes are accurate and versatile vocal mimics of the vocalizations of other species, but little is known about how males deploy their repertoire of mimicked sounds across contexts. Using extended focal watches, we recorded adult males displaying during the breeding season. We found that males mimicked heterospecific songs and nonalarm calls during ‘recital’ displays usually performed while they were perched and visually inconspicuous. In contrast, during visually conspicuous ‘dance’ displays, commonly performed on display mounds, males only mimicked heterospecific alarm calls. While much rarer than recital displays, dance displays were associated with the final stages of mate choice preceding copulation. These results provide the first evidence of any species varying its repertoire of mimicked sounds with different sexual contexts. Previous work suggests that mimicry in dance displays functions deceptively to manipulate the antipredator responses of females during the final stages of courtship. However, the structure and context of recital mimicry closely resembles the sexual advertisement song performed by nonmimicking songbirds. Given the importance of mimicry in the acoustic ecology of lyrebirds, our results suggest that with recital song males advertise the quality of their mimicry as it likely benefits both male and female offspring. Our finding that male superb lyrebirds mimic functionally distinct heterospecific vocalizations during different modes of courtship suggests that the evolution and maintenance of avian vocal displays are more complex than previously thought.

Heterospecific Song and Ecological Politics: Whale Song and Crumb's Vox Balaenae

What does it mean to say that a whale has a voice, that a whale sings? Why is it important to human beings to say that whales sing? On the one hand, the use of musical terms to describe cetacean vocalisation is a matter of convenience. On the other hand, the history of human reception of these sounds shows that the usage is a trace of a determination and a desire: a determination to portray cetaceans as intelligent, articulate creatures; a desire to know of what they sing, and perhaps to sing with them. In this paper, I interpret George Crumb’s Vox Balaenae as both a response to the voices of whales and as an elegy of sorts that acknowledges the incommensurability of cetacean and human voices. My interpretation is both historical and music-analytical, and begins by exploring the subtle and occasionally not-so-subtle campaign in the late 1960s and early 1970s by Scott McVay, Roger Payne, and others to marshal public support for a whaling ban and conservation, an effort that included supplying composers, Crumb among them, with tapes of humpback whale vocalizations. With this context in place, I show how—as in much of Crumb’s music—shifting referential pitch-class collections articulate the gulf between the cetacean song we hear but cannot sing, and human music to which we do not—and likely never will—know if whales are listening.

Effect of sympatry on discrimination of heterospecific song by varied tits

Many animals recognize their own species through acoustic signals, and erroneous recognition incurs costs. Birds discriminate between conspecific and heterospecific songs; for example, male territory owners respond aggressively to songs of conspecific males within their territories, but not to heterospecific songs. This discrimination is affected by the costs associated with territory defence behaviours. In populations where birds live with a related species that sings similar songs, males may waste time and energy on useless territory defence behaviours if they mistakenly recognize heterospecific songs as conspecific ones. On the other hand, if males in allopatric populations recognize conspecific songs as heterospecific songs, they may risk losing territories because the songs are sung by conspecific rivals in the absence of heterospecifics. For this reason, the potential costs of erroneous species recognition are expected to differ between sympatric and allopatric populations. Thus, it can be hypothesized that, in species without interspecific territoriality, males in sympatry respond less strongly or not at all to heterospecific songs similar to their own, and males in allopatry respond equally to heterospecific and conspecific songs. In this study, I examined this hypothesis using varied tits, Poecile varius , in the Ryukyu Archipelago, Japan. Their songs are similar in structure to those of confamilial Japanese tits, Parus minor . I used song playbacks and evaluated the aggressive responses of 355 territorial males in seven populations of varied tits. Overall, varied tit males responded strongly to conspecific songs but only weakly to Japanese tit songs. Furthermore, responses to the heterospecific songs were much weaker in the sympatric populations than in the allopatric ones, which is consistent with the hypothesis tested. This study suggests that when secondary contact occurs, song discrimination may influence the effectiveness of territorial behaviours and the reproductive success of individual males from sympatric and allopatric populations. • I studied the effect of closely related species on song discrimination in birds. • I used playbacks of conspecific and heterospecific songs and compared the responses. • Male responses were weaker to heterospecific songs than to conspecific songs. • This effect was greater in sympatric populations than in allopatric populations. • Coexistence of related species may influence discrimination of conspecific song.

Early acoustic experience alters genome-wide methylation in the auditory forebrain of songbird embryos

Early exposure to salient cues can critically shape the development of social behaviors. For example, both oscine birds and humans can hear and learn to recognize familiar sounds in ovo and in utero and recognize them following hatching and birth, respectively. Here we demonstrate that different chronic acoustic playbacks alter genome-wide methylation of the auditory forebrain in late-stage zebra finch (Taeniopygia guttata) embryos. Within the same subjects, immediate early gene activation in response to acute con- or heterospecific song exposure is negatively correlated with methylation extent in response to repeated daily prior exposure to the same type of stimuli. Specifically, we report less relative global methylation following playbacks of conspecific songs and more methylation following playbacks of distantly-related heterospecific songs. These findings offer a neuroepigenomic mechanism for the ontogenetic impacts of early acoustic experiences in songbirds.

Rufous horneros perceive and alter temporal coordination of duets during territorial interactions

Temporal coordination of duets consists of nonrandom overlap, alternation or association between rhythms of acoustic elements. Since duet coordination presumably requires high attentiveness between signallers, the coalition quality hypothesis suggests it may indicate the ability or motivation of partners to engage cooperatively in aggressive interactions against intruders. To test this hypothesis, we monitored behavioural as well as vocal responses in a playback experiment conducted with a polyphonal duetting bird, the rufous hornero, Furnarius rufus . We used three categories of treatments in the experiment, which totalled six treatments: duet playbacks that varied in phrase overlap and coordination of temporal rhythms; nonoverlapped (consecutive) solos; and a control heterospecific song. We predicted that birds would respond more strongly to playbacks of coordinated duets than to uncoordinated duets, and also to playbacks of uncoordinated duets than to nonoverlapping male and female solo songs. Coordinated duets (degree of phrase overlap) provoked the weakest response across conspecific stimuli, whereas the responses to uncoordinated duets and nonoverlapped solos were similar. However, partners produced more highly coordinated duets (degree of phrase overlap) in response to coordinated duets (association of phrase rhythms), when compared to all other stimuli. These results suggest that territorial pairs not only perceive but also alter their degree of temporal coordination of duets during territorial interactions. In addition, partners seem to behave cautiously and with more coordinated duets when responding to paired intruders that produce coordinated duets. Our results partially support the coalition quality hypothesis, suggesting that duet coordination may indicate the ability of partners to cooperatively engage in aggressive interactions. • Rufous horneros were exposed to playbacks of duets varying in temporal coordination. • Coordinated duets provoked the weakest response from birds. • However, partners increased duet coordination in response to coordinated duets. • Results suggest that highly coordinated duets may be intimidating to individual birds.

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.

Dinner and a show: The role of male copulatory courtship song and female blood-feeding in the reproductive success of Lutzomyia longipalpis from Lapinha, Brazil

Lutzomyia longipalpis is the main vector of visceral Leishmaniasis in the Americas and is composed of a species complex. Males of this sand-fly produce acoustic signals during copulation and different patterns are observed among Brazilian populations. Such acoustic signals are commonly involved in species recognition. However, since the song is only produced during copulation it is not clear how it affects mating success or contributes to sexual isolation. Another aspect that may affect reproductive success is the presence of food. Since hematophagy is such an important aspect of L. longipalpis biology, we wanted to test if blood-feeding can influence the reproductive behaviour of this insect. We performed crossing experiments removing males' wings (silencing them) and playing back either the homo-specific or the hetero-specific song to either unfed or blood-fed females. Our results showed that both songs and blood-feeding affect insemination success, but not the frequency of copulation. In trials where females were not blood-fed song clearly affected insemination; males with wings, and males with homo-specific song playback had a higher insemination success than wingless males (no song) and trials with hetero-specific song. Blood-feeding females prior to the trials increased insemination in all groups including the control group which suggests that mating happens simultaneously with, or immediately after, the blood meal. Blood-fed females also seemed to discriminate less against the wrong song or the lack of song (wingless) one day after feeding, however trials with the correct song still had higher insemination rates. Altogether, our results show that both the male copulatory courtship songs and female blood-feeding are important for reproductive success and as such are important components of the sexual behaviour of L. longipalpis.

Auditory processing in the zebra finch midbrain: single unit responses and effect of rearing experience.

In birds the auditory system plays a key role in providing the sensory input used to discriminate between conspecific and heterospecific vocal signals. In those species that are known to learn their vocalizations, for example, songbirds, it is generally considered that this ability arises and is manifest in the forebrain, although there is no a priori reason why brainstem components of the auditory system could not also play an important part. To test this assumption, we used groups of normal reared and cross-fostered zebra finches that had previously been shown in behavioural experiments to reduce their preference for conspecific songs subsequent to cross fostering experience with Bengalese finches, a related species with a distinctly different song. The question we asked, therefore, is whether this experiential change also changes the bias in favour of conspecific song displayed by auditory midbrain units of normally raised zebra finches. By recording the responses of single units in MLd to a variety of zebra finch and Bengalese finch songs in both normally reared and cross-fostered zebra finches, we provide a positive answer to this question. That is, the difference in response to conspecific and heterospecific songs seen in normal reared zebra finches is reduced following cross-fostering. In birds the virtual absence of mammalian-like cortical projections upon auditory brainstem nuclei argues against the interpretation that MLd units change, as observed in the present experiments, as a result of top-down influences on sensory processing. Instead, it appears that MLd units can be influenced significantly by sensory inputs arising directly from a change in auditory experience during development.

Interactions between sibling species of treecreepers Certhia familiaris and C. brachydactyla in the Pyrenees and the mistaken identity hypothesis

ABSTRACT Capsule Aggressive interactions between two treecreeper species were probably the result from misidentification of heterospecifics rather than resource competition. Aims To test the alternative hypotheses that aggressive interactions between two sibling species, the Eurasian Treecreeper Certhia familiaris and the Short-toed Treecreeper Certhia brachydactyla, were the result of resource competition or misidentification of the species involved. Methods Interspecific interactions were investigated by direct observation and territory mapping of the two species during 12 years in a 25 ha plot in the Pyrenees. In addition, we performed playback experiments to test the behavioural response of both species to the heterospecific song in three sympatric areas of the Pyrenees, and in an adjacent area where only the Short-toed Treecreeper occurred. Results Territories largely overlapped between the two species. Subsequently, distance between the two species’ nearest nests was significantly shorter than distance between the same species’ nearest nests. Overall, the Short-toed Treecreeper was more aggressive towards the sibling species than the Eurasian Treecreeper. However, in contrast to what might be expected according to the resource-competition hypothesis, it was not significantly more aggressive in sympatry than in allopatry. Conclusion These results suggest that the aggressive behaviour of the Short-toed Treecreeper was mainly caused by the birds mistaking the identity of Eurasian Treecreepers, and had little impact on the cohabitation between the two species.

Singing behaviour of ruby‐crowned kinglets Regulus calendula in relation to time‐of‐day, time‐of‐year and social context

Observational field studies provide insight on the multifunctional nature of birdsong. For example, if song production were limited to pre‐fertilization, then that would suggest a mate attraction function. If it were used throughout the breeding season and in response to intruding males, then that would suggest a territorial defence function. In the present study, we determined the daily and seasonal singing patterns of male ruby‐crowned kinglets Regulus calendula in Labrador, Canada, using microphone arrays in two breeding seasons. Using a playback experiment, we simulated a territorial intrusion to compare the structure of songs produced while defending a territory to the structure of songs produced during solo and contest singing. Singing peaked in the early part of the breeding season and then declined continuously for the remainder of the season, which suggests that the songs function in mate attraction. Singing peaked 2–3 h after dawn, and then declined steadily until it stopped at 10 pm. Some nocturnal singing was observed, but no dawn singing was observed. A high probability of signal overlap by heterospecific songs at dawn would hinder signal recognition and explain the observed delay in peak singing activity. Vocal responses to playback suggested a function in territory defence. However, there were no significant differences in the duty cycle, frequency modulation and bandwidth of songs in relation to the context of song production, though songs were shorter in the intrusion context than during solo singing. Overall, the study provides the first quantitative description of the effects of time of day, time of year and social context on singing behaviour in this understudied species.

The Role of Nestling Acoustic Experience in Song Discrimination in a Sparrow

Oscine songbirds are an ideal system for investigating how early experience affects vocal behavior. Young songbirds face a challenging task: how to recognize and selectively learn only their own species’ song, often during a time-limited window. Because birds are capable of hearing birdsong very early in life, early exposure to song could plausibly affect recognition of appropriate models; however, this idea conflicts with the traditional view that song learning occurs only after a bird leaves the nest. Thus, it remains unknown whether natural variation in acoustic exposure prior to song learning affects the template for recognition. In a population where sister species, golden-crowned and white-crowned sparrows, breed syntopically, we found that nestlings discriminate between heterospecific and conspecific song playbacks prior to the onset of song memorization. We then asked whether natural exposure to more frequent or louder heterospecific song explained any variation in golden-crowned nestling response to heterospecific song playbacks. We characterized the amount of each species’ song audible in golden-crowned sparrow nests and showed that even in a relatively small area, the ratio of heterospecific to conspecific song exposure varies from 0 to 20%. However, although many songbirds hear and respond to acoustic signals before fledging, golden-crowned sparrow nestlings that heard different amounts of heterospecific song did not behave differently in response to heterospecific playbacks. This study provides the first evidence that song discrimination at the onset of song learning is robust to the presence of closely related heterospecifics in nature, which may be an important adaptation in sympatry between potentially interbreeding taxa.

Mate Choice Behavior of Female Field Crickets Is Not Affected by Exposure to Heterospecific Calling Songs.

Many animals produce acoustic signals to mark territories and attract mates. When different species produce acoustic signals simultaneously, the signals create a noisy environment, with potential acoustic interference between species. Theoretical studies suggest that such reproductive interference may have strong effects on species interaction. For example, the inferior resource competitor can survive if its disadvantage is counterbalanced by superiority in reproductive interference. Two field cricket species, Teleogryllus occipitalis (Audinet-Serville) (Orthoptera: Gryllidae) and Loxoblemmus equestris Saussure (Orthoptera: Gryllidae), cooccur in the same habitat. A previous study has shown that L. equestris is an inferior species to T. occipitalis in terms of resource competition. Therefore, we predicted that mate location and choice behavior of female T. occipitalis would be negatively affected by the acoustic signals of L. equestris and tested this with a series of playback experiments. The mate choice behavior of female T. occipitalis was not significantly affected by the calling song of L. equestris. Our results suggest that the acoustic interference does not explain the cooccurrence of the two species in the same habitat.

Zebra finches go wild! Experimental cultural evolution of birdsong

Abstract Vocal learning in songbirds is guided by experience and experience-independent factors. Previously, lineages of zebra finches founded by isolate-reared tutors showed cultural evolution to wild-type song. This suggests that experience-independent biases affect song development even in the absence of wild-type song. We hypothesized that cultural evolution of song depends on both experience-independent biases and tutor songs available. We predicted that songs more distant from wild-type would take longer to culturally evolve toward wild-type features. We bred zebra finches in three groups of lineages in which offspring of each generation served as tutors for the next. Lineages were founded with males singing wild-type song, isolate song, or heterospecific song. The two experimental lineages exhibited rapid cultural evolution of song with many temporal and spectral features converging to wild-type within two generations. However the rate of change differed depending on song features measured, and took longer for lineages founded with heterospecific song.

Heterospecific song quality as social information for settlement decisions: an experimental approach in a wild bird

Assessing local habitat quality via social cues provided by conspecific or heterospecific individuals sharing the same needs is a widespread strategy of social information use for breeding habitat selection. However, gathering information about putative competitors may involve agonistic costs. The use of social cues reflecting local habitat quality acquired from a distance, such as acoustic cues, could therefore be favoured. Bird songs are conspicuous signals commonly assumed to reliably reflect producer quality, and thereby local site quality. Birds of various species have been shown to be attracted to breeding sites by conspecific and heterospecific songs, and to use conspecific song features as information on producer (and by extension habitat) quality. Whether they can do the same with heterospecific song features, and whether this depends on the individual's own phenotype and especially its competitive ability, remains unknown. We used a playback experiment in a wild population of collared flycatchers, Ficedula albicollis, a species known to eavesdrop on the presence and performance of dominant great tits, Parus major. We tested whether flycatchers, whose aggressiveness was experimentally assessed, preferred to settle near playback of a high-quality great tit song (i.e. song with large repertoire size, long strophes, high song rate), a low-quality great tit song or a chaffinch song (control). Among old females, aggressive ones preferred to settle near playback of high-quality tit song and avoided playback of low-quality tit song, while less aggressive females preferred to settle near playback of low-quality tit song. Male personality or age did not influence settlement decisions. This shows that collared flycatcher females use great tit song quality features as information for settlement decisions, although this depended on their own competitive ability and/or previous experience with great tit songs. Our study therefore further illustrates the complex condition-dependent use of heterospecific social information for breeding habitat selection.

Male responses to conspecific and heterospecific songs in two field cricket species

Many animals produce acoustic signals for displaying their territoriality to other males and attracting mating partners. However, the acoustic signals are often eavesdropped on by other species. If a species with higher competitive ability eavesdrops on the acoustic signals of a species with lower competitive ability, the former can deprive the latter of their suitable calling sites. Therefore, the species with higher competitive ability exhibits a positive response to the acoustic signals of those with lower competitive abilities, whereas the species with lower competitive ability exhibits a negative response to the calling songs of those with higher competitive abilities. In the present study, male responses to conspecific and heterospecific song in two field cricket species Teleogryllus occipitalis (Audinet-Serville 1839) (Gryllidae) and Loxoblemmus equestris Saussure 1877 (Gryllidae) were investigated by playback experiments. T. occipitalis has larger body size than L. equestris. Both species did not exhibit precise negative or positive responses to conspecific and heterospecific songs. The results suggest that the cricket species do not utilize heterospecific song to acquire their calling sites.