The Effect of Timing of Female Vibrational Reply on Male Signalling and Searching Behaviour in the Leafhopper Aphrodes makarovi

Sexual communication in animals often involves duetting characterized by a coordinated reciprocal exchange of acoustic signals. We used playback experiments to study the role of timing of a female reply in the species-specific duet structure in the leafhopper Aphrodes makarovi (Hemiptera: Cicadellidae). In leafhoppers, mate recognition and location is mediated exclusively by species- and sex-specific substrate-borne vibrational signals and a female signal emitted in reply to male advertisement calls is essential for recognition and successful location of the female. In A. makarovi, males have to initiate each exchange of vibrational signals between partners, and in a duet the beginning of a female reply overlaps the end of the male advertisement call. Results of playback treatments in which female replies were delayed and did not overlap with the male call revealed that in order to trigger an appropriate behavioural response of the male, female reply has to appear in a period less than 400 ms after the end of the initiating male call. Results also suggest that males are not able to detect a female reply while calling, since female reply that did not continue after the end of male call triggered male behaviour similar to behaviour observed in the absence of female reply. Together, our results show that vibrational duets are tightly coordinated and that the species-specific duet structure plays an important role in mate recognition in location processes.     

Insect duets: underlying mechanisms and their evolution

Abstract. Duetting between the sexes in insects involves the use of airborne acoustic signals, substrate vibration and bioluminescence. Unlike avian duets, in which females may initiate the interaction, among insects the duet starts with the male, and the female usually provides a brief reply. Insect duets are characterized by low variance in the reply latency of the female (the time between a key element in the male call and the onset of the female's response). Duetting is reviewed principally in Orthoptera but also in Plecoptera, Hemiptera, Neuroptera and bioluminescence in the Coleoptera. The mechanisms of the duet are examined first, followed by evolution and the associated change in searching strategies of each sex. As defined, the duet has distinct temporal characteristics and these are compared with acoustic interactions among males in those species that exhibit male–male synchrony and alternation. For insects, the key element of a duet for species' recognition is low variance in the reply latency of females. In cases in which the male's initiating signal is extremely short, reply latencies become indicators of species' recognition. However, in those species in which the initiating male call is under selection through female choice, the male call is predictably longer and occasionally more complex. Under these circumstances, reply latencies often increase, creating an opportunity for alternative male tactics. When alternative tactics exist in nature, males may decrease the intensity of their call, insert a trigger pulse that signals to the female the end of its complex call, or males may even add a masking signal that obscures the competing signal.     

Evidence for High Variability in Temporal Features of the Male Coda in Müller’s Bornean Gibbons (<Emphasis Type="Italic">Hylobates muelleri</Emphasis>)

Most pair-living primate species engage in duets, wherein males and females produce coordinated vocalizations. Previous analyses of male gibbon contributions to the duet have shown that calls are individually distinct. Here we investigate variation in the temporal and spectral parameters in the male contribution to the duet, also known as the coda, of wild, nonhabituated male Müller’s Bornean gibbons (Hylobates muelleri), recorded both opportunistically and as a response to playbacks at the Stability of Altered Forest Ecosystems site in Sabah, Malaysia. We used linear discriminant function analysis to estimate the intra- and interindividual variation in 13 spectral and temporal parameters of the vocalizations (N?=?337) of 31 male gibbons. To further understand how call features vary within and between individuals we used a multivariate, variance components model to investigate how variance in features was partitioned at these two levels. We could identify males with a 66% accuracy using leave-one-out cross-validation, a relatively low score compared to female Müller’s Bornean gibbons and males of other species. We found that for some features (such as maximum frequency of the notes) most of the variance occurred between males, but for others (specifically total duration of the call and duration of rest in between notes) most of the variance occurred within a single male. Overall, male Müller’s Bornean gibbon coda vocalizations showed greater variability relative to their female counterparts, raising questions about potential differences in the function of the male and female contributions to the duet in Müller’s Bornean gibbons and the gibbon taxon as a whole.     

The Responses of Duetting Antbirds to Stereo Duet Playback Provide Support for the Joint Territory Defence Hypothesis

In multiple animal taxa, including many birds and primates, members of mated pairs produce coordinated acoustic displays known as duets. By observing the behaviour of territorial animals as they respond to playback‐simulated duets of rivals, we can gain insight into the behavioural significance of vocal duets. Playback experiments, however, have been conducted across a very narrow range of duetting animals. Furthermore, many studies have been conducted with single‐speaker playback, whereas stereo‐speaker playback offers more spatially realistic simulation of duets. Moreover, by evaluating the reactions of animals to separate loudspeakers broadcasting male and female duet contributions, we can study the interactions of both males and females with same‐sex vs. opposite‐sex rivals. We used a paired experimental design to broadcast duet stimuli through a single‐speaker and a stereo‐speaker apparatus to 30 pairs of duetting barred antshrikes Thamnophilus doliatus in Costa Rica. Our goals were (1) to evaluate whether territorial antbirds respond more aggressively to male vs. female duet components and (2) to assess aggressive responses of antbirds towards single‐speaker vs. stereo‐speaker playback. Neither males nor females differentiated between the loudspeaker simulating the male vs. female duet contribution during stereo‐speaker playback trials. Barred antshrikes displayed significantly stronger responses to stereo‐speaker playback compared with single‐speaker playback. Males displayed stronger playback responses than females with closer, quicker and more vocal responses. These results provide evidence for a joint resource defence function of antbird duets given that pairs responded together with equivalent intensity to male and female simulated intruders. This is the first study to show that although duetting is an aggressive territorial signal, birds do not necessarily respond to sex‐specific components of duets. Our results support the idea that spatially realistic stereo presentation of duet stimuli is critical for experimental duet research.     

Aufbau, Variabilit?t und m?gliche Funktionen des Rufduetts beim ThermometerhuhnLeipoa ocellata

Zusammenfassung Beim ThermometerhuhnLeipoa ocellata tragen die Partner eine Paares ein Rufduett vor. Der Anteil des besteht aus einer Rufreihe, die sich aus einer Folge von 2–7 identischen, zweisilbigen Rufen zusammensetzt. Das trägt einen einzelnen, obertonreichen und langgezogenen Ruf vor. Sowohl der Ruf des als auch die Rufreihe des wird in Serien vorgetragen. Innerhalb einer solcher Ruf- bzw. Rufreihenserie können mehrere Duette auftreten. Die Rufe sind jedoch nicht ausschließlich an das Duett gebunden. Die Variabilität im Aufbau des Duetts äußert sich im Zeitpunkt des Einsatzes des antwortenden Vogels, in der Anzahl der -Rufe während des Duetts und in der Anzahl der Einheiten, aus denen sich der Duettanteil des zusammensetzt. Das beginnt signifikant häufiger als das eine Serie, in der ein oder mehrere Duette vorkommen. Ebenso ist es häufiger der Initiator des ersten in dieser Serie liegenden Duetts. Das Duett dient wohl hauptsächlich zur Festigung des Zusammenhalts zwischen den Paarpartnern. Es erfüllt jedoch von seinen physikalischen Eigenschaften her auch die Bedingungen, die für ein territorial wirksames Signal gelten.

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Structure, variability and possible functions of duetting in the Mallee FowlLeipoa ocellata

Summary In the Australian Mallee Fowl,Leipoa ocellata, both and of a pair are involved in a call duet. The part of the consists of a sequence of 2–7 identical two-syllable calls. The contributes a single long-drawn-out call rich in harmonics. The call of the as well as the call sequence of the are presented in series. Within a series of calls () or call sequences () several duets can occur. The respective vocalizations, however, do not exclusively occur during the duet.The variability in the details of the duet expresses itself in the lag period after which the mate responds, in the number of -calls during the duet, and in the number of calls within the call sequence of the . The begins a series during which one or several duets occur significantly more frequently than the . The circumstances under which duetting occurs indicate that duet calling mainly serves to maintain the pair bond. Moreover, due to its physical characteristics the duet also seems to be suited to serve as a territorial signal.

     

Calling and Duetting Behavior in the Leafhopper <Emphasis Type="Italic">Balclutha incisa</Emphasis> (Hemiptera: Cicadellidae: Deltocephalinae): Opportunity for Female Choice?

Male Balclutha incisa (Cicadellidae: Deltocephalinae) produces substrate-borne signals as well as sounds produced by wing fluttering. Males produce 6 signal types that are associated with different behavioral activities: (i) cleaning, (ii) calling, (iii) precopulatory, (iv) copulation, (v) postcopulatory behavior, and (vi) aggression. Within each category signals have a high degree of stereotypy in regard to their temporal structure. Females produce two kinds of signals: (i) a duetting signal in response to the male, and (ii) an introductory or preparatory signal before the main signal. The sexes duet, with the female placing its signal immediately after the first two components of the males call, with an interval of some 136 ms. We discuss the role of the male calls in attracting females and the importance of the duet in maintaining a temporary pair-bond.     

Antiphonal duetting in Steere’s liocichla (Liocichla steerii): male song individuality and correlation between habitat and duetting behavior

We studied duet song and vocal duetting behavior in an endemic Taiwanese passerine, Steeres liocichla (Liocichla steerii). We found that the leading male song in duets was highly individualistic. Also, we found duetting behavior varied significantly across different habitat types. Females were more likely to answer male songs in densely vegetated, steep forest habitat compared to open agricultural habitat. These findings provide quantitative evidence for vocal individuality for a duet song and provide tentative support for the idea that females are duetting to reveal their location to their mates.     

Acoustic Monitoring Reveals Congruent Patterns of Territorial Singing Behaviour in Male and Female Tropical Wrens

Many animals defend territories against conspecific individuals using acoustic signals. In birds, male vocalizations are known to play a critical role in territory defence. Territorial acoustic signals in females have been poorly studied, perhaps because female song is uncommon in north‐temperate ecosystems. In this study, we compare male vs. female territorial singing behaviour in Neotropical rufous‐and‐white wrens Thryothorus rufalbus, a species where both sexes produce solo songs and often coordinate their songs in vocal duets. We recorded free‐living birds in Costa Rica using an eight‐microphone Acoustic Location System capable of passively triangulating the position of animals based on their vocalizations. We recorded 17 pairs of birds for 2–4 consecutive mornings and calculated the territory of each individual as a 95% fixed kernel estimate around their song posts. We compared territories calculated around male vs. female song posts, including separate analyses of solo vs. duet song posts. These spatial analyses of singing behaviour reveal that males and females use similarly sized territories with more than 60% overlap between breeding partners. Territories calculated based on solo vs. duet song posts were of similar size and similar degrees of overlap. Solos and duets were performed at similar distances from the nest for both sexes. Overall, male and female rufous‐and‐white wrens exhibit very similar spatial territorial singing behaviour, demonstrating congruent patterns of male and female territoriality.     

Rivalry between Stink Bug Females in a Vibrational Communication Network

In the field, male pheromone attracts stink bugs to meet on the same plant and triggers females to call a male by the emission of the calling song. As first among Pentatomidae we describe female rivalry in Chinavia impicticornis, C. ubica and Euschistus heros. Rivalry starts in C. impicticornis by synchronized exchange of the first type of the female calling song pulse trains and proceeds by one of them either to change pulse trains from the first to the second type or to produce readily repeated single pulses. Both reactions either inhibit calling of the rival female or trigger her to respond by alternation with the second type of the calling song pulse trains. Female rivalry in C. ubica differs by the emission of the rival song that replaces alternation with the second type of the calling song typical for C. impicticornis. E. heros females synchronize pulses of the calling song duets and induce emission of the female rival song by one of them that partly inhibits singing of the other. These competitive interactions in Chinavia species reduce the proportion of couples when compared with single couples on a plant. Contrary to both Chinavia species, E. heros female rivalry does not inhibit male response, male signals overlap female emissions and create complex vibrations with modified amplitude modulation pattern caused by interference.     

Duet structure provides information about pair identity in the red-crowned crane (Grus japonensis)

We studied the acoustic features of the endangered red-crowned crane (Grus japonensis), and, specifically, whether or not the duets carry information about a mating pair identity. The population of this species in the wild is only approximately 2,000 individuals. In 2003–2006, we recorded 343 duets from eight captive and two wild pairs. All of the duets contained an introduction, an unordered alternation of pair mate calls, followed by the main part, representing the regular sequence of syllables, containing 1–2 male and 1–4 female calls per syllable. We subdivided the syllables into five types, by the number of male and female calls per syllable, and analyzed the occurrence of the different syllable types in the duets of the ten pairs. The analysis showed the sustainable pair-specific use of particular syllable types through the years. The discriminant analysis standard procedure, based on seven frequency and temporal parameters of male and female calls, showed 97.7% correct assignment to the pair, which is significantly higher than random values. The high pair specificity of the duet acoustic structures provides the basis for call-based censuses. This would enable the monitoring of the red-crowned crane mating pairs in their natural habitat.     

Context, Structural Variability and Distinctiveness of California Towhee (Pipilo crissalis) Vocal Duets

Avian vocal duets occur when paired birds produce temporally and structurally coordinated vocalizations. Duets are given by members of many species from taxonomically distinct lineages and show great variety in form that often reflects function. By describing the structure of vocal duets we can learn about the diversity of communication signals present in nature and also gain insight into the evolution and operation of those signals. This study quantified the usage patterns and acoustic structure of California towhee duet vocalizations, and tested the distinctiveness of duets among different pairs. California towhee duets consist of a 'squeal' vocalization that is highly unlike the species-typical call note or male advertizement song. California towhees duet an average of three times per hour during the breeding season, and all duets are accompanied by an approach response that brings duetting partners into close spatial proximity. Males and females produce duet contributions with the same syllabic structure. Individual birds produce highly variable squeal vocalizations that are distinctive enough to signal identity. California towhee duet characteristics indicate that the squeal vocalization has evolved separately from other vocal traits in this species and was promoted by natural selection as a duet-specific vocalization. Duet usage patterns and structure suggest that these communication signals function in a cooperative context.     

Siberian crane duet as an individual signature of a pair: comparison of visual and statistical classification techniques

Vocal individuality varies between species and/or ontogenesis stages depending on needs in the vocal recognition, but also estimation of individual differences depends on the method of analysis. We studied pair-specific differences of duets elicited by mating pairs of Siberian crane Grus leucogeranus. We quantitatively described the duet structure and compared visual and statistical classification methods of pair identification by duet. Three methods were used: discriminant analysis, method of classification trees and visual classification of spectrogram. We found significant interpair differences. The pairs differ by duet structure that is by the ratio of male- and female-initiated duets and by the ratio of the number of male to female calls; temporal-frequency duet characteristics are pair-specific, too. All methods showed high interpair differences, which exceeded random values significantly. Discriminant analysis stepwise procedure based on 11 parameters resulted in 97.3% of correctly assigned duets. Human observers correctly assigned 80.7% of spectrograms. Our data provide a basis for remote monitoring of this endangered species with a wild population of only 3,000 birds.     

First Evidence of Vibrational Communication in Homotomidae (Psylloidea) and Comparison of Substrate-Borne Signals of Two Allied Species of the Genus <Emphasis Type="Italic">Macrohomotoma</Emphasis> Kuwayama

Substrate-borne signals are widely used in Hemiptera and are known to be utilized in mate searching and recognition. Within this Order, the superfamily Psylloidea is a diverse taxon which uses this type of signal modality during mating behavior between the two sexes. This study describes and compares the previously unreported vibrational communication of two closely related species of Macrohomotoma (Homotomidae). Both genders of these two species, Macrohomotoma gladiata Kuwayama 1908 and Macrohomotoma robusta Yang 1984, emit vibrational signals and establish duets during mating. The structure of male calling consists of two chirps while the female response is a single chirp. Males may sometimes follow the female response by emitting a single chirp that sounds similar to the female response with respect to the chirp duration and dominant frequency. This behavior is novel among Psylloidea and its potential function is discussed. Specific comparison of signal characteristics has revealed that the two species of Macrohomotoma are clearly distinguishable from each other which opens the possibility of acoustic signals being used for species delineation.     

Duetting in the Titi monkey Callicebus cupreus: structure,pair specificity and development of duets

Duets from a total of 6 female and 6 male titi monkeys (Callicebus cupreus) were analysed in order to provide an in-depth analysis of the duet structure, to investigate whether duets are pair specific and to examine whether duets of newly formed pairs differ from those of established pairs. Callicebus duets are composed of alternately uttered male and female contributions. Duets were pair specific as a result of a summation of individual attributes of the two mates rather than due to unidirectional or reciprocal song adaptation by mates. The two examined newly formed pairs produced species-typical duets from the first day on, but their duets showed greater variability in sequence durations than those of established pairs.     

Breeding season length predicts duet coordination and consistency in Neotropical wrens (Troglodytidae)

Many animals produce coordinated signals, but few are more striking than the elaborate male–female vocal duets produced by some tropical songbirds. Yet, little is known about the factors driving the extreme levels of vocal coordination between mated pairs in these taxa. We examined evolutionary patterns of duet coordination and their potential evolutionary drivers in Neotropical wrens (Troglodytidae), a songbird family well known for highly coordinated duets. Across 23 wren species, we show that the degree of coordination and precision with which pairs combine their songs into duets varies by species. This includes some species that alternate their song phrases with exceptional coordination to produce rapidly alternating duets that are highly consistent across renditions. These highly coordinated, consistent duets evolved independently in multiple wren species. Duet coordination and consistency are greatest in species with especially long breeding seasons, but neither duet coordination nor consistency are correlated with clutch size, conspecific abundance or vegetation density. These results suggest that tightly coordinated duets play an important role in mediating breeding behaviour, possibly by signalling commitment or coalition of the pair to mates and other conspecifics.     

Duet function in the yellow-naped amazon, Amazona auropalliata: evidence from playbacks of duets and solos

The question of why animals participate in duets is an intriguing one, as many such displays appear to be more costly to produce than individual signals. Mated pairs of yellow-naped amazons, Amazona auropalliata, give duets on their nesting territories. We investigated the function of those duets with a playback experiment. We tested two hypotheses for the function of those duets: the joint territory defense hypothesis and the mate-guarding hypothesis, by presenting territorial pairs with three types of playback treatments: duets, male solos, and female solos. The joint territory defense hypothesis suggests that individuals engage in duets because they appear more threatening than solos and are thus more effective for the establishment, maintenance and/or defense of territories. It predicts that pairs will be coordinated in their response (pair members approach speakers and vocalize together) and will either respond more strongly (more calls and/or more movement) to duet treatments than to solo treatments, or respond equally to all treatments. Alternatively, the mate-guarding hypothesis suggests that individuals participate in duets because they allow them to acoustically guard their mate, and predicts uncoordinated responses by pairs, with weak responses to duet treatments and stronger responses by individuals to solos produced by the same sex. Yellow-naped amazon pairs responded to all treatments in an equivalently aggressive and coordinated manner by rapidly approaching speakers and vocalizing more. These responses generally support the joint territory defense hypothesis and further suggest that all intruders are viewed as a threat by resident pairs.     

东黑冠长臂猿鸣叫声谱分析

2007 年9 月至2009 年6 月,利用Sony TC - D5 Pro2 录音机、Sony C - 76 指向性话筒和Sony 录音磁带对广西邦亮自然保护区3 群东黑冠长臂猿的鸣叫进行了录音,对每群录音效果较好的5 个声音用Signal/ RTS 4.0 软件进行声谱分析。结果表明:东黑冠长臂猿叫声的频率较高,最高频率已经达到甚至超过了5 kHz;雄性的鸣叫声由起始音(boom)、简单的重复音节(aa notes)、调节前音节(pre-modulated note)和调节音句(modulated phrases)组成,雌性长臂猿一般只会发出一种固定而刻板的激动鸣叫,二者互相配合组成结构复杂的二重唱。通常,二重唱由成年雄性发起和结束,并占主导地位。同时,将东黑冠长臂猿二重唱的声谱结构与近缘种西黑冠长臂猿和海南长臂猿进行比较,结果显示雄性和雌性的叫声、以及二者配合发出的激动鸣叫序列在三者之间都有明显差异。因此,从声谱特征角度可以有效论证这三种长臂猿独立物种的分类地位。     

Functions of duetting in the tropical boubou, Laniarius aethiopicus: territorial defence and mutual mate guarding

Duetting, found in many animal taxa, is still a poorly understood form of signalling behaviour despite numerous hypotheses to explain its function. One contentious issue is whether duetting is a cooperative endeavour or signals conflict between the sexes. We studied the function of duetting in the tropical boubou, using interactive playback experiments. We staged encounters by presenting paired birds with four variants of each of four duet types (neighbour and stranger solos and neighbour and stranger duets). Multiple lines of evidence suggest that both joint territorial defence and mutual mate guarding are important functions of duetting, and that both cooperation and conflict between males and females have shaped duetting behaviour. Of a repertoire of 12 duet types, eight were used for joint territorial defence. Two of these eight duet types were probably also used for mutual mate guarding, suggesting that individual duets can have multiple functions. We found an unusual response for duetting birds in that females often synchronized notes with male solo playback to form precise duets. In turn, males attempted to jam the song of rivals when females joined the song of male solo playback, providing further evidence for the importance of acoustic mate guarding. Song jamming by males has not previously been described for duetting species. Finally, we suggest that the repertoire of duet types is used to fine-tune territorial encounters in a network environment of multiple interactants.     

Differentiating the evolution of female song and male–female duets in the New World blackbirds: Can tropical natural history traits explain duet evolution?

Female bird song and combined vocal duets of mated pairs are both frequently associated with tropical, monogamous, sedentary natural histories. Little is known, however, about what selects for duetting behavior versus female song. Female song likely preceded duet evolution and could drive apparent relationships between duets and these natural histories. We compared the evolution of female song and male–female duets in the New World blackbirds (Icteridae) by investigating patterns of gains and losses of both traits and their relationships with breeding latitude, mating system, nesting pattern, and migratory behavior. We found that duets evolved only in lineages in which female song was likely ancestral. Both female song and duets were correlated with tropical breeding, social monogamy, territorial nesting, and sedentary behavior when all taxa were included; however, correlations between duets and these natural history traits disappeared when comparisons were limited to taxa with female song. Also, likelihood values supported stronger relationships between the natural history traits and female song than between these traits and duets. Our results suggest that the natural histories thought to favor the evolution of duetting may in fact be associated with female song and that additional selection pressures are responsible for the evolution of duets.     

Vocal variation in <Emphasis Type="Italic">Chiroxiphia boliviana</Emphasis> (Aves; Pipridae) along an Andean elevational gradient

Bird vocalizations are likely shaped both by natural and sexual selection. Here we test the sensory-drive hypothesis, which states that communication signals diverge as a direct adaptation to the signaling environment and can evolve to minimize degradation and maximize transmission. We examined the effects of elevation and other habitat variables on variation in vocalizations of Chiroxiphia boliviana (Aves, Pipridae) along an elevational gradient (1300–2500 m) in cloud and humid montane forests in the Andes of Bolivia. We also conducted sound transmission experiments to determine if reverberation and attenuation changed along the gradient. Reverberation increased at higher elevations, and attenuation decreased at higher elevations and increased for higher frequencies. We recorded vocalizations from ~?50 individuals throughout the elevational gradient and examined variation in duration and bandwidth of short calls (used as contact calls between males), 2 display calls (advertisement for females) and 2 types of male–male duets (including interval times between males). Duration of short calls, display 1 and duet 1 increased with elevation. Bandwidth of short calls increased at mid-elevation categories and decreased at high elevations, whereas bandwidth of display 1 and duet 1 decreased with elevation. We also directly related the transmission properties to vocalizations and found that bandwidth of short calls decreased with reverberation and attenuation, bandwidth of display 2 decreased with reverberation, and duration of duet 1 both increased and decreased with attenuation (at 3 and 4 kHz, respectively). This study suggests that vocalizations by C. boliviana may be adapted to the habitat transmission properties along the elevational gradient; and perhaps that increasing song length and concentrating energy within a narrow bandwidth may lead to an increase in amplitude and improvement in transmission. Overall, our results support the sensory-drive hypothesis and suggest that this form of selection is likely common along tropical elevational gradients.