THE SIGNIFICANCE OF MULTI-NOTE ADVERTISEMENT CALLS IN A REED FROG,HYPEROLIUS TUBERILING UIS

ABSTRACT

The reed frog Hyperolius tuberilinguis is a prolonged breeder with an advertisement call that varies in complexity from one to six click notes. Call complexity increases with chorus size, but calls containing more than three notes are rare. In playback experiments to males, subjects responded by increasing the complexity of their calls, without closely matching the stimulus and rarely exceeding the stimulus in complexity. Stimuli less complex than their own evoked a reduction in complexity. Call repetition rate remained unchanged in the responses. In two-choice phonotaxis experiments, females discriminated against one-note calls, and two- and three-note calls were the most attractive. Males thus adjust their calling in the presence of neighbours to a pattern most preferred by females. Calls of higher complexity may be more easily detected or located by females in the noisy environment of a chorus.     

Advertisement calls of Guenther’s frog Hylarana guentheri (Anura: Ranidae) during the breeding season

Acoustic signalling is the most important form of communication in anuran amphibians. Here we recorded and analysed the calls of 18 male Guenther’s frogs (Hylarana guentheri) from the wild during the breeding season. The advertisement calls of H. guentheri were composed of from a single note to five notes, with three-note calls the most recorded. All individuals produced calls around 600 Hz but calls ranged from 470 to 2600 Hz. Comparing the differences between individuals calls, we found within-male coefficients of variation (CV_w) of call intensity, the fundamental frequency, the first formant, the second formant, the third formant and the fourth formant were static (less than 5% variation), whereas those of note duration, call duration, call interval, numbers of pulses and dominant frequency were dynamic (larger than 15% variation). Comparisons of the call characteristics of H. guentheri in this study with other studies from China, Singapore and Vietnam found call characteristics varied greatly between the five different locations.     

The role of frequency modulation in controlling the response of mallard ducklings (Anas platyrhynchos) to conspecific distress calls

Three experiments examined the response of mallard ducklings to conspecific distress calls. In experiment 1, a synthetic call was constructed from a single distress note, by recording it on a digital disc and then using a software routine to regularly repeat this stored note with the average period (267 ms) of the original call. Ducklings were then tested for their tendency to inhibit their own distress vocalizations in response to either this synthetic call, the original call, or a constant-frequency tone mimic; they showed a significantly stronger inhibitory response to the synthetic call than to the tone mimic, but an even stronger response to the original call. The former result indicated that the synthetic call was an effective stimulus, and suggested that some aspect of the frequency modulation found in distress notes is required to evoke the normal duckling inhibitory response. The latter result further suggested that the acoustic variability found in the original call, but not the synthetic call, may be of importance for controlling duckling behaviour. Experiment 2 demonstrated that several other minor differences between the synthetic call and original call (number of notes per call and the digital recording of the synthetic call) could not account for the difference in duckling response to these two calls. Finally, in experiment 3, two additional synthetic stimuli were constructed from the digitized note, by first excising either the initial (front-chop) or terminal (rear-chop) frequency modulation found in each distress note, then creating amplitude envelopes for these new notes similar to that of the unaltered note, and finally repeating these notes to form calls with the same note period as the original call. The ducklings tested with the synthetic normal-note call and synthetic front-chop call showed a significantly stronger inhibitory response than the ducklings tested with the synthetic rear-chop call and the tone mimic. These results indicate that the terminal descending frequency sweep is an important feature of distress notes for triggering the response of ducklings to conspecific distress calls.     

Call recognition and female choice in a treefrog with a multicomponent call

Acoustic mating signals are typically species‐specific, and often additionally are subject to directional female preferences. Male executioner treefrogs, Dendropsophus carnifex, produce a multicomponent advertisement call composed of an introductory screech note followed by two or more click notes. Here, we tested (i) call recognition by comparing female directed phonotaxis towards individual and combined call components: screech vs. clicks vs. screech + clicks, (ii) female preferences for greater numbers of click notes and (iii) female preferences for faster call rates. The results demonstrated that screeches and clicks, presented either separately or together as a complete call, evoke similar female responses, suggesting that either note was sufficient to elicit a mate‐recognition response. Additionally, females preferred calls with greater numbers of click notes and with faster call rates. We interpret these results within the context of female mate selection in natural choruses.     

Multisensory signals trigger approach behaviour in the fire-bellied toad Bombina orientalis: sex differences and call specificity

Animal communication often involves multimodal signals, and interactions between sensory modalities can trigger unique responses in receivers. Response to social signals was investigated in fire-bellied toads by exposing them to playback of male calls (advertisement and release calls) and a video clip of a male conspecific in the laboratory. The cues were presented in isolation and as a combined bimodal stimulus, and approach frequency, latency to approach and time spent around the stimulus source were measured. No positive phonotaxis was observed toward the advertisement call, both during the day and during a phonotaxis trial performed at night. However, females, but not males, approached with greater frequency, lower latency, and spent more time near the source of the bimodal stimulus in an experiment involving the advertisement call. Female response was specific to the advertisement call, as approach was not increased when the release call was used. Males, on the other hand, did not show increased approach in the advertisement call experiment, but approached with greater frequency the bimodal stimulus involving the release call within the first minute of stimulus presentation. The findings suggest that females orient toward calling males and that males eavesdrop on release calls, but in both cases a visual stimulus is also needed to trigger a response. Social approach in Bombina orientalis is thus dependent on multisensory cues, and the nature of the interaction between sensory modalities depends on receiver sex and call type.     

沼水蛙繁殖期鸣声特征及鸣叫节律

鸣叫对无尾两栖类动物的生存与繁殖起重要作用。蛙类的鸣叫行为受到环境因素影响表现出一定的节律性。2016年8和9月,采用录音机和指向性话筒,在野外录制了57只沼水蛙（Hylarana guentheri）的鸣声并对其鸣声特征进行分析;通过悬挂录音笔和自动温湿度记录仪研究了沼水蛙鸣叫节律（17 d）及其与环境温度、相对湿度的关系。结果显示,沼水蛙的鸣声由1 ~ 4个音节组成,不同类型鸣声间的音节主频、音节时长存在显著差异（P < 0.05）。该物种全天具有鸣叫行为,13:00 ~ 14:00时为鸣叫高峰期。白天单音节鸣声、双音节鸣声、三音节鸣声、总鸣声和总音节的数量较夜晚显著增加（P < 0.01）。鸣声数量和音节数量均与环境温度呈正相关（P < 0.01）。结果表明,沼水蛙通过改变音节数量、音节主频和音节时长改变鸣叫策略。沼水蛙的鸣叫行为具有昼夜节律性且受环境温度的影响。     

Male Calling Behavior and Female Choice in the Neotropical Treefrog Hyla microcephala

The effect of stimulus call complexity and calling rate on the vocal responses of males and female mate choice was studied in Hyla microcephala in Panama. Males increased the number of notes in their calls in response to increases in stimulus call complexity during both playback of 1 to 8-note advertisement calls and during natural interactions. However, precise matching of the number of notes in stimuli and responses did not occur consistently. Males also increased calling rates if stimuli were presented above prestimulus rates. Two-stimulus choice experiments demonstrated that females prefer both higher calling rates and greater call complexity, indicating that the ways males change their vocal behavior during interactions increases their attractiveness to potential mates. Tests in which the relative intensity of a high and low rate stimulus was varied indicated that females prefer stimuli with higher total sound energy. In a natural chorus, it is likely that females simply approach males giving the most conspicuous calls.     

Syntactical Organization of the Gargle Vocalization of the Black-capped Chickadee,Parus atricapillus

The gargle is a complex call of the black-capped chickadee Parus atricapillus associated with agonistic interactions. A large sample of calls was recorded from five sites in southeastern Wisconsin. Three sites were near one another and the other two with a different dialect pattern were more distant (all sites were within 15 km of each other). A typical call consists of about 6 notes selected from an array of about 15 different note-types that are shared among individuals in the same population. Note-types are given in many combinations, and any individual may deliver many different variations. Analysis of two- and three-note sequences shows a syntactical organization with certain note-types much more likely to precede or follow than others. In some cases linkage between note-types was nearly complete. Some differences occurred among individuals and sites, but general organizational rules were similar. One effect on ordering was acoustical structure of the notes. Higher pitched, shorter duration notes were more likely at the beginning than the end of the call which often consisted of trills. Organization of the gargle was compared to that of the chick-a-dee call of the same species. Similarities include recombinant properties, general acoustic rules and syntax. A major difference may be that in chick-a-dee calls various note combinations constituting a call have different meanings, while the various note combinations comprising an individual's repertoire of gargles may be functionally equivalent.     

Sound production in the whitemouth croaker and relationship between fish size and disturbance call characteristics

The whitemouth croaker produces two different sounds using extrinsic sonic muscles: (1) male advertisement calls during the spawning season and (2) disturbance calls, produced by both sexes. The advertisement call, related to courtship, was recorded in the field and from two marked spawning males of 28 and 30.5 cm L_T in the laboratory. It consists of individual pulses with average durations of 19.7 ms and 17.8 ms for the two males respectively, interpulse intervals of 496 ms and 718 ms, and dominant frequencies of 280 Hz and 316 Hz. Pulses are emitted in bouts of one to three min duration. Disturbance calls consist of a burst of pulses produced at short intervals, and the pulse duration, interpulse interval and dominant frequency of the pulses average 19.8 ms, 17.1 ms, and 363 Hz, respectively. Dominant frequency and interpulse interval decrease and pulse duration increases with fish size. Sound characteristics change markedly in young of the year individuals (lower than 25 cm L_T) after which they appear to stabilize. Higher dominant frequency in the advertisement than in the disturbance call and the relationship of dominant frequency to pulse duration suggest that dominant frequency is determined as a forced response to muscle contraction parameters rather than by the natural frequency of the swimbladder.     

No pre-existing biases for heterospecific call traits in the frog Physalaemus enesefae

Previous phonotaxis studies with two species of the Physalaemuspustulosus species group indicated that female preferences for several heterospecific call traits resulted from sensory biases inherited from a common ancestor. In phonotaxis experiments, we determined whether Physalaemus enesefae, a distant relative of the P. pustulosus group, showed similar preferences for call traits not present in conspecific males. We presented females with a choice between the typical conspecific advertisement call and the same call to which we digitally appended a chuck from P. pustulosus, a squawk from P. freibergi, and an amplitude-modulated prefix from P. pustulatus. In addition we presented the advertisement call in doublets, a trait peculiar to P. coloradorum. We also analysed male vocal behaviour evoked in response to the same suite of stimuli. Physalaemus enesefae females did not prefer the calls of their own males with appended heterospecific traits over unmodified calls, nor conspecific calls in doublets over single calls. The lack of preference among females was not the result of a behavioural polymorphism. Female responses to repeated presentations of the same stimulus pair were not consistent. Males also did not show an enhanced vocal response to altered calls relative to the typical conspecific call. Consequently, there are no pre-existing biases for these heterospecific call traits in P. enesefae; pre-existing preferences in the P. pustulosus group could have been inherited from an ancestor not shared with P. enesefae, but data from other closely related species are needed to confirm this conclusion. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Calls of the black drum (Pogonias cromis: Sciaenidae): geographical differences in sound production between northern and southern hemisphere populations

Because of apparent reproductive isolation between Northern and Southern hemisphere populations of the black drum Pogonius cromis, we tested the hypothesis that advertisement calls from a southern population would differ from known calls of North American populations. Additionally, we quantified disturbance and advertisement calls, their changes with fish size and sex, not previously examined in this species. Unlike most sciaenids, both sexes of P. cromis possess robust sonic muscles, and both produce disturbance calls when handled. However, only males produce an advertisement call used in courtship. The disturbance call consists of a variable train of short-duration pulses (average 23?ms). The duration, interpulse interval, and dominant frequency of pulses are similar in males and females and change developmentally: pulse duration and interpulse interval increase and dominant frequency decreases with fish size. Advertisement calls, recorded in the field and in captivity, are long-duration (average 184?ms) and tonal. Based on variation in fundamental frequency, which decreases with fish size, field choruses are composed of different-sized individuals. The duration of advertisement calls, about a third of those from Florida populations, suggests genetic differentiation between northern and southern populations.     

Acoustic,auditory, and morphological divergence in three species of neotropical frog

Advertisement calls, auditory tuning, and larynx and ear morphology were examined in 3 neotropical frogs, Hyla microcephala, H. phlebodes and H. ebraccata, H. microcephala has the highest call dominant frequency (6.068 kHz) and basilar papilla tuning (5.36 kHz). H. phlebodes and H. ebraccata calls have lower dominant frequencies (3.832 and 3.197 kHz respectively) and basilar papilla tuning (2.79 and 2.56 kHz). The primary call notes of H. ebraccata are longer (181.6 ms) than those of H. microcephala (95.5 ms) or H. phlebodes (87.3 ms). Morphometric analysis suggests that temporal call features differ as laryngeal musculature changes, in the process changing the overall size of the larynx. The spectral aspects of the call differ as head size, and hence the size of its resonating and radiating structures, changes, modifying the dominant frequency of calls by accentuating their higher harmonics when head size decreases. Decreasing head size decreases the size of the middle and inner ear chambers, changing the mechanical tuning of the ear in the same direction as the change in dominant frequency. These changes result in divergent spectral-temporal characteristics of both the sending and receiving portions of the acoustic communication system underlying social behavior in these frogs.Abbreviations AP amphibian papilla - BEF best excitatory frequency - BP basilar papilla - dB SPL decibels sound pressure level re:20 N/m²     

Crepuscular Changes in Emission Rate and Parameters of the Boatwhistle Advertisement Call of the Gulf Toadfish, Opsanus Beta

We quantified crepuscular variation in the emission rate and call properties of the boatwhistle advertisement call of Gulf toadfish, Opsanus beta, from a field recording of a natural population of nesting males in the Florida Keys. Their calls are more variable and complex than previously reported. A call typically starts with a grunt followed by one to five tonal boop notes (typically two or three) and lasts for over a second. The first boop is considerably longer than later ones, and intervals between boops are relatively constant until the final interval, which approximately doubles in duration. Positions of fish are fixed and calls are sufficiently variable that we could discern individual callers in field recordings. Calling rate increases after sunset when males tend to produce shorter calls with fewer notes. Analysis by number of notes per call indicates some individuals decrease the number of initial grunts and the duration of the first note, but most of the decrease results from fewer notes. To our knowledge this sort of call plasticity has not been demonstrated before in fishes. We suggest that call shortening lowers the chances of overlapping calls of other males and that the small amount of time actually spent producing sound (total on time) is an adaptation to prevent fatigue in sonic muscles adapted for speed but not endurance.     

Golden-marmot Alarm Calls. II. Asymmetrical Production and Perception of Situationally Specific Vocalizations?

Many species produce alarm calls that vary according to situation. An implicit assumption for these species is that production and perception of situationally specific alarm calls is symmetrical: perceivers respond to variation produced by signalers. The companion paper to this one (Blumstein 1995) showed that golden marmots (Marmota caudata aurea) produce variable alarm calls that vary in proportion to the degree of risk the caller perceives. Calls produced in higher-risk situations have fewer notes than calls produced in lower-risk situations. In this study, to determine the salience of the number of notes per call in eliciting different responses in conspecific perceivers, I played back three-note alarm calls, eight-note alarm calls, and the non-alarm vocalization of a local bird to adult golden marmots. Although marmots responded differently to bird calls and alarm calls, vigilance responses to the different alarm calls were similar. Several explanations may account for the apparent insensitivity to alarm-call variation: golden marmots may require additional contextual cues to properly interpret alarm calls, perceptual abilities do not parallel production abilities, or calls may serve a generalized alerting function.     

Signalling plasticity and energy saving in a tropical bushcricket

Males of the tropical bushcricket Mecopoda elongata synchronize their acoustic advertisement signals (chirps) in interactions with other males. However, synchrony is not perfect and distinct leader and follower roles are often maintained. In entrainment experiments in which conspecific signals were presented at various rates, chirps displayed as follower showed notable signal plasticity. Follower chirps were shortened by reducing the number and duration of syllables, especially those of low and medium amplitude. The degree of shortening depended on the time delay between leader and follower signals and the sound level of the entraining stimulus. The same signal plasticity was evident in male duets, with the effect that the last syllables of highest amplitude overlapped more strongly. Respiratory measurements showed that solo singing males producing higher chirp rates suffered from higher metabolic costs compared to males singing at lower rates. In contrast, respiratory rate was rather constant during a synchronous entrainment to a conspecific signal repeated at various rates. This allowed males to maintain a steady duty cycle, associated with a constant metabolic rate. Results are discussed with respect to the preference for leader signals in females and the possible benefits males may gain by overlapping their follower signals in a chorus.     

Evolutionary and neurobiological implications of selective phonotaxis in the spring peeper (Hyla crucifer)

Males of the spring peeper (Hyla crucifer) in central Missouri produce frequency-modulated, sinusoidal advertisement calls with a duration of 90–250 ms, and a mid-point frequency of 2800–3360 Hz. The frequency of the call is inversely correlated with body size. In playback experiments with synthetic stimuli, females did not prefer a frequency-modulated call to a call of constant frequency. Females preferred a call with a duration of 150 ms to sounds with durations of 40, 75 and 400 ms; a call of 300 ms was just as attractive as the 150-ms call. Females preferred a call of 2875 Hz to alternatives of 4000 Hz and 2600 Hz. The auditory system of H. crucifer is thus only roughly tuned to the temporal and spectral properties of the advertisement call. The female's specificity with respect to duration alone is adequate for species recognition, but intraspecific mate choice based on call frequency is extremely unlikely.     

Temporal order and the evolution of complex acoustic signals

The evolution of complex signals may be favoured by hidden preferences or pre-existing sensory biases. Females of two species of grey treefrogs (Hyla chrysoscelis and Hyla versicolor) were tested with combinations of a conspecific advertisement call and acoustic appendages. Appendages consisted of aggressive calls and segments of advertisement calls from conspecific males and males of three other species and bursts of filtered noise. When a wide variety of these acoustic appendages followed the advertisement call, the resulting compound signal was often more attractive than the same advertisement call alone. When the same appendages led advertisement calls, however, the compound signal was never more attractive and sometimes less attractive. The order effect was especially strong in tests of H. versicolor in which advertisement-call duration was decreased. These results cannot be explained by a general pre-existing bias for extra stimulation per se. Rather, order and other effects may constrain the evolution and subsequent modification of complex and extravagant signals, examples of which have been reported for a wide range of taxa.     

Complex Vocal Responses to Conspecific Calls in Whistling Frogs Eleutherodactylus johnstonei: Playback Experiments in the Field

We simulated the presence of an acoustic competitor by broadcasting conspecific playbacks to males of Johnstone's whistling frog, Eleutherodactylus johnstonei, in the field. We broadcast calls that differed in duration (short, typical, and long), dominant frequency (high, typical, and low), and period (short, typical, and long), and analyzed male vocal responses. We tested the hypothesis that males respond by escalating vocally when they are exposed to female‐attractive calls and by ignoring unattractive ones. At the population level, males responded to playbacks in ways that would potentially increase their attractiveness with regard to solo calling: males increased the duration, reduced the dominant frequency, and increased their calling effort (duty cycle), despite an increase in call period. The modification of call duration occurred only in response to playbacks of low‐frequency calls, long calls, and short‐period calls (selective response), while the modification of the dominant frequency was independent of the characteristic of the playback (fixed response). Contrary to the expected, males did not reduce the call period when they were exposed to attractive playbacks. At the ultimate level, the results suggest energy‐saving strategies. In addition, males seem to trade off call period for the avoidance of acoustic interference with attractive calls as calling effort was typically increased by increasing call duration but only rarely by reducing the call period. Interactive playbacks are necessary to better understand the calling strategies of males of E. johnstonei.     

Who is Calling? Intraspecific Call Variation in the Aromobatid Frog Allobates femoralis

Many territorial species respond less aggressively to familiar neighbours than to unfamiliar floating strangers based on individual differences in acoustic signals. This form of social recognition, termed neighbour–stranger discrimination (NSD) or dear-enemy phenomenon has been reported so far from three anuran species. To investigate the potential of auditory signal features to convey information on sender's identity, we determined patterns of within-male and between-male variability in the advertisement call of the aromobatid frog Allobates femoralis . We examined 285 calls from 19 males to assess those call properties showing sufficient and reliable inter-individual differences to function as possible recognition cues. Beside calls per call bout and call rate, all other examined call properties were more variable among males than within males. Generally, temporal call features showed higher between- and within-male variability ratios than spectral properties and contributed mostly to distinguish individual males in the discriminant-function analysis. Mean classification success of 64.9% correctly assigned calls to individual males is mainly attributable to three temporal call properties (duration of note 1 and 4, note repetition rate). Altogether, our results suggest that there is sufficient variation in the advertisement call to discriminate statistically among individual males. However, assessed call differences between A. femoralis males were rather small, suggesting that potential NSD might be based either on a combination of call features or even on the whole pattern of individual call variation instead on single call properties. Habituation–discrimination experiments in the field using modified playback signals to test for differential behavioural responses are required to confirm this hypothesis.