Acoustic signals of a solitary subterranean rodent Ctenomys talarum (Rodentia: Ctenomyidae): physical characteristics and behavioural correlates

The purpose of this study was to analyse and describe vocalizations of a solitary subterranean rodent, Ctenomys talarum. In adult C. talarum five different sounds (four true vocalizations and one mechanical sound) were recorded during different behavioural contexts. Using data from the laboratory and literature, we classified these vocalizations as territorial, distress, and mating calls. We found that the vocalization range in C. talarum is shifted towards low frequencies, which transmit better in underground burrows and match well the hearing range described for other species of subterranean rodents. These low-frequency vocalizations, also found in other non-related subterranean rodents, may reflect an adaptation to the acoustic conditions of the habitat. Electronic Publication     

Acoustic communication in the sexual behaviour of the leafhopper, Amrasca devastans

ABSTRACT. Males of Amrasca devastans (Distant) (Homoptera, Cicadellidae) emit 'croaking' sounds in phrases of two to six pulses which are transmitted through the plant on which the animal is feeding. Females, if present on the same plant, respond to such croaks by ceasing movements and emitting their own substrate-borne 'cooing' sounds in single-pulsed phrases. These coos stimulate the males to emit their croaks more frequently, and to commence 'dancing' movements, during which they approach the female (whether she is visible or not); the sounds of the two sexes alternate with each other throughout. On reaching the female, the male emits 'snoring' sounds and stands at her side, partly in response to seeing her and partly in response to mechanical contact. Thereafter, the male emits 'pattering' sounds while raising and vibrating his wings and extending the tip of his abdomen towards the female's abdomen. Finally, the genitalia of the two sexes are interlocked for copulation, during which 'drumming' sounds occur.     

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     

Receiver discriminability drives the evolution of complex sexual signals by sexual selection

A hallmark of sexual selection by mate choice is the evolution of exaggerated traits, such as longer tails in birds and more acoustic components in the calls of birds and frogs. Trait elaboration can be opposed by costs such as increased metabolism and greater predation risk, but cognitive processes of the receiver can also put a brake on trait elaboration. For example, according to Weber's Law traits of a fixed absolute difference will be more difficult to discriminate as the absolute magnitude increases. Here, we show that in the Emei music frog (Babina daunchina) increases in the fundamental frequency between successive notes in the male advertisement call, which increases the spectral complexity of the call, facilitates the female's ability to compare the number of notes between calls. These results suggest that female's discriminability provides the impetus to switch from enhancement of signaling magnitude (i.e., adding more notes into calls) to employing a new signal feature (i.e., increasing frequency among notes) to increase complexity. We suggest that increasing the spectral complexity of notes ameliorates some of the effects of Weber's Law, and highlights how perceptual and cognitive biases of choosers can have important influences on the evolution of courtship signals.     

Negative feedback from maternal signals reduces false alarms by collectively signalling offspring

Within animal groups, individuals can learn of a predator's approach by attending to the behaviour of others. This use of social information increases an individual's perceptual range, but can also lead to the propagation of false alarms. Error copying is especially likely in species that signal collectively, because the coordination required for collective displays relies heavily on social information. Recent evidence suggests that collective behaviour in animals is, in part, regulated by negative feedback. Negative feedback may reduce false alarms by collectively signalling animals, but this possibility has not yet been tested. We tested the hypothesis that negative feedback increases the accuracy of collective signalling by reducing the production of false alarms. In the treehopper Umbonia crassicornis, clustered offspring produce collective signals during predator attacks, advertising the predator's location to the defending mother. Mothers signal after evicting the predator, and we show that this maternal communication reduces false alarms by offspring. We suggest that maternal signals elevate offspring signalling thresholds. This is, to our knowledge, the first study to show that negative feedback can reduce false alarms by collectively behaving groups.     

Begging coordination between siblings in Black-headed Gulls

Communication behaviours are now considered from a signallers–receivers network perspective. This concept seems well suited to the study of interactions between parents and offspring in birds, so far mainly treated as a dyadic signalling system involving the brood or a single chick as a signaller and the parent as a receiver. Family conflicts over resource allocation drive parent–offspring and sib–sib communication. In the Black-headed Gull Larus ridibundus, parents respond to the whole-brood begging intensity and siblings often synchronize their begging signalling thus limiting individual effort. By monitoring five nests of two-chick broods during the whole rearing period in the nest, we show how an intra-brood simultaneity of begging emerges from successive phases of solitary begging of junior and senior nestlings. Although this result remains preliminary due to the sample size, it underlines a dynamical aspect of chicks’ behaviour. Because they always favour coordinated begging and because they elevate their response threshold across the rearing period, parents may play a major role in the plasticity of begging behaviour.     

The role of frequency, phase and time for processing of amplitude modulated signals by grasshoppers

Acoustic signals consist of pressure changes over time and can thus be analyzed in the frequency- or in the time-domain. With behavioural experiments we investigated which frequency components (FC) are necessary for the recognition of the periodic envelope of the conspecific song by females of the grasshopper Chorthippus biguttulus. Further, we determined up to which frequency component phase information is required which would indicate processing in the time domain. Responses of females revealed that signals composed of FC between 10 and 50 Hz are sufficient for recognition of the song envelope. A systematic reduction in the number of FC showed that no single frequency component was required; signals without the fundamental frequency were still highly attractive and only three FC may be sufficient for song recognition. Phase changes for frequencies up to 40 Hz strongly changed the attractiveness of song signals but only little at 50 Hz. Females were also tested with rectangular signals in which pause duration was varied. Evidently, and despite the high attractiveness of song signals with a “missing fundamental”, females evaluated the attractiveness of signals in the time-domain, since the selectivity for pause duration predicted the responses to signals composed from FC well.     

Abdominal odours of young,low-ranking European rabbit mothers are less attractive to pups: an experiment with animals living under natural breeding conditions

Lactating rabbit females (Oryctolagus cuniculus) emit abdominal, ventral odour cues that are involved in guiding the pups to the nipples. We tested the impact of the females’ social rank and age on the emission of this odour signal; both factors are highly collinear in wild rabbits and we did not aim to disentangle them in our study. We predicted that the abdominal odours of young, low-ranking females, which are usually more stressed and have a comparatively lower body condition, should be less attractive to pups than those of older, high-ranking females. For the experiment, we caught females from a population of wild-type European rabbits living in a large field enclosure. Pairs of adult females were placed in boxes with wire-mesh floor fixed over an arena with three rabbit pups aged 4–7 days old. First, we evaluated the effectiveness of our two-choice design by testing lactating females (LF) against non-lactating (NLF) controls (n = 17 pairs). In accordance with recent studies, the pups showed a clear preference for lactating females by means of a higher exploration time and more local searching under the ventral region of these females. In a second experiment, the pups chose between lactating 1-year-old, low-ranking females (Y/LRF) and older, high-ranking females (O/HRF) (n = 10 pairs). These latter assays suggested a comparatively lower attractiveness of Y/LRF females to pups searching for milk. Although the pups showed no significant preference in exploration behaviour, they preferably directed local searching events to the abdominal region of O/HRF females. In conclusion, our study suggests that mother–offspring chemosensory communication is modified by the mother’s age and social rank, i.e., by a complex of factors that are strongly linked in rabbit females in the wild.     

Song recognition in the grasshopper Chorthippus biguttulus is not impaired by shortening song signals: implications for neuronal encoding

The communication signals in many grasshopper species are composed of multiple repetitions of highly stereotyped subunits, and thus provide redundancy. In a behavioural paradigm, we tested the ability of males of the grasshopper Chorthippus biguttulus to recognize shortened versions of the communication signals of conspecific females. Males reliably responded to a three-subunits signal (250 ms), i.e. to a signal of less than a quarter of the natural duration. This performance is remarkable in view of the substantial adaptation and the variability present in the spiking responses of auditory interneurones. These behavioural results will impose constraints for investigating possible encoding mechanisms used by the grasshoppers' auditory system. Accepted: 1 September 1998     

回声定位蝙蝠及其声通讯

综述了回声定位蝙蝠种类及其发声方式,回声定位信号的主要类型及回声定位信号声学特征,多普勒频移对长CF／FM蝙蝠的主要作用,简介了蝙蝠求偶和母婴识别等内声通讯行为,提出了一些尚待解决的重要问题。     

Noise affects the shape of female preference functions for acoustic signals

The shape of female mate preference functions influences the speed and direction of sexual signal evolution. However, the expression of female preferences is modulated by interactions between environmental conditions and the female's sensory processing system. Noise is an especially relevant environmental condition because it interferes directly with the neural processing of signals. Although noise is therefore likely a significant force in the evolution of communication systems, little is known about its effects on preference function shape. In the grasshopper Chorthippus biguttulus, female preferences for male calling song characteristics are likely to be affected by noise because its auditory system is sensitive to fine temporal details of songs. We measured female preference functions for variation in male song characteristics in several levels of masking noise and found strong effects of noise on preference function shape. The overall responsiveness to signals in noise generally decreased. Preference strength increased for some signal characteristics and decreased for others, largely corresponding to expectations based on neurophysiological studies of acoustic signal processing. These results suggest that different signal characteristics will be favored under different noise conditions, and thus that signal evolution may proceed differently depending on the extent and temporal patterning of environmental noise.     

HERITABILITY OF NESTLING BEGGING INTENSITY IN THE HOUSE SPARROW (PASSER DOMESTICUS)

Evolutionary theory of parent–offspring conflict assumes that offspring food solicitation behavior, known as begging, and parental response to begging are subjected to selection and coevolution. This assumption implies that begging intensity should be heritable, at least to some degree. Although some studies have suggested that begging is heritable, the evidence for this is rare and mostly indirect. To assess the heritability of begging we used artificial selection, sibling analysis, and the monitoring of begging intensity in four generations of cross-fostered captive house sparrow nestlings. We also contrasted the heritability of begging with that of morphological traits, known to be heritable in this species. Our results show that adult wing length and body mass were heritable as expected. The heritability estimates of the visual and vocal components of nestling begging (standardized for food deprivation and body mass) were low to moderate, as expected for behavioral traits in general, and lower than previously reported for passerine birds. Our sibling analysis shows that common environment had much greater effect on begging than genetic origin, suggesting that begging evolution may be strongly influenced by gene–environment interaction, probably through the mechanisms that adjust begging response to environmental and social conditions.     

Acoustic characteristics of eight common Chinese anurans during the breeding season

Anurans often have species-specific vocalizations. To quantify and compare the characteristics of anuran calls in Gutianshan National Nature Reserve, Zhejiang Province, we recorded the advertisement calls of eight species belonging to four families (Ranidae, Microhylidae, Megophryidae and Bufonidae) from June to September 2012 using Sony ICD-FX8 IC recorders. All recordings were analyzed using the "Praat" software. Five acoustics parameters were measured, including temporal traits (call duration, number of notes or pulse number/call) and spectral traits (fundamental frequency, the first three formants and dominant frequency). The characteristic parameters of Microhyla ornate and Fejervarya limnocharis calls were different as were the calls of some populations of the same species recorded in different regions. The advertisement calls of the eight species were specific. Our study has provided a useful reference for identifying the calls of some common Chinese anurans.     

Acoustic signals and echolocation system of the dolphin

Two-channel recording of acoustic signals from two quasi-stationary dolphins has previously suggested that the dolphin echolocation system is more complex than discussed earlier, and includes at least four sonars. In the present work, two-channel recording of signals, analysis and interpretation of their functions were continued in terms of physical acoustics, signal theory and echolocation. The results indicate that the echolocation system of dolphins involves four organs to produce probing signals of five different types, which implies different mechanisms of their processing by the dolphin hearing; its operation corresponds to as many as six varieties of sonar systems. The results are of importance for studying the echolocation system of Odontoceti and for improving sonars and radars.     

外科治疗囊性听神经瘤14例临床观察

目的：探讨囊性听神经瘤的临床特点及手术经验。方法：回顾分析2006年1月-2010年12月我院收治的14例囊性听经瘤的临床资料。结果：肿瘤全切除12例,不全切除2例,无死亡病例,术后4例病人面瘫加重,1例病人听力丧失。结论：与实质性听神经瘤相比,囊性听神经瘤体积较大,病程短,始发症状不典型,颅神经常被累及,可不发生内听道扩大,脑积水发生率低,手术效果差。     

Acoustic characteristics and variations in grunt vocalizations in the oyster toadfish <Emphasis Type="Italic">Opsanus tau</Emphasis>

Acoustic communication is critical for reproductive success in the oyster toadfish Opsanus tau. While previous studies have examined the acoustic characteristics, behavioral context, geographical variation, and seasonality of advertisement boatwhistle sound production, there is limited information on the grunt or other non-advertisement vocalizations in this species. This study continuously monitored sound production in toadfish maintained in an outdoor habitat for four months to identify and characterize grunt vocalizations, compare them with boatwhistles, and test for relationships between the incidence of grunt vocalizations, sound characteristics and environmental parameters. Oyster toadfish produced grunts in response to handling, and spontaneous single (70% of all grunts), doublet (10%), and trains of grunts (20%) throughout the May to September study period. Grunt types varied in pulse structure, duration, and frequency components, and were shorter and of lower fundamental frequency than the pulse repetition rate of boatwhistles. Higher water temperatures were correlated with a greater number of grunt emissions, higher fundamental frequencies, and shorter sound durations. The number of grunts per day was also positively correlated with daylength and maximum tidal amplitude differences (previously entrained) associated with full and new moons, thus providing the first demonstration of semilunar vocalization rhythms in the oyster toadfish. These data provide new information on the acoustic repertoire and the environmental factors correlated with sound production in the toadfish, and have important implications for seasonal acoustic communication in this model vocal fish.     

野生动物声音定位系统模拟实验及精度分析

声音通讯是动物交流的重要手段。利用声音定位野生动物,可以降低对动物的干扰,并且不受光线和生境的限制。2013年4~5月,在河南董寨国家级自然保护区利用鸣禽的鸣唱录音,检验了利用声音定位的精度。共选择4个样方,在样方的四个边角各放1台录音机,并在样方内随机选择播放点,播放雀形目鸟类的鸣唱。通过同一段声音到达不同录音机的时间差定位声源的位置,并与实际测量的位置相比较。结果得出5种鸣禽基于鸣声定位的平均精度为(1.89±0.99)m。本研究为该项技术在国内鸟类研究中的首次尝试,希望能为利用声音监测野生动物提供参考。