Small Mammals Ignore Common Rules: A Comparison of Vocal Repertoires and the Acoustics between Pup and Adult Piebald Shrews Diplomesodon pulchellum

A common rule for mammals vocalizing in the human audible frequency range (20 Hz–20 kHz) suggests that calls are higher in fundamental frequency (f0) in the young than in adults, because of the smaller sound‐producing structures of the young. Exclusions are rare, for example the pups of Asian house shrews (Suncus murinus) make some call types of the same or higher pitch than adults. In this study, calls from 62 piebald shrews (Diplomesodon pulchellum), 37 1 to 10‐d‐old pups from 10 litters and 25 adults were acoustically investigated in captivity. We found eight call types, all within the human audible frequency range: short and long low‐frequency squeaks with nearly flat contour, high‐frequency squeaks with modulated contour, high‐frequency squeaks with fractured contour, short and long screeches, clicks and whimpers. Seven call types were shared by pups and adults, suggesting that this vocal repertoire commences at birth. Against the common rule, the f0 of squeaks was the same in pups and adults, and the f0 of clicks and screeches was even higher in adults than in pups. These results suggest a non‐descending ontogenetic pathway that not follows the common physical relationship, of the lower f0 for the larger vocal folds.     

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.     

Acoustic emissions of Sorex unguiculatus (Mammalia: Soricidae): Assessing the echo‐based orientation hypothesis

Shrew species have been proposed to utilize an echo‐based orientation system to obtain additional acoustic information while surveying their environments. This system has been supported by changes in vocal emission rates when shrews encounter different habitats of varying complexity, although detailed acoustic features in this system have not been reported. In this study, behavioral experiments were conducted using the long‐clawed shrew (Sorex unguiculatus) to assess this orientation system. Three experimental conditions were set, two of which contained obstacles. Short‐click, noisy, and different types of tonal calls in the audible‐to‐ultrasonic frequency range were recorded under all experimental conditions. The results indicated that shrews emit calls more frequently when they are facing obstacles or exploring the experimental environment. Shrews emitted clicks and several different types of tonal calls while exploring, and modified the use of different types of calls for varying behavior. Furthermore, shrews modified the dominant frequency and duration of squeak calls for different types of obstacles, that is, plants and acrylic barriers. The vocalizations emitted at short inter‐pulse intervals could not be observed when shrews approached these obstacles. These results are consistent with the echo‐based orientation hypothesis according to which shrews use a simple echo‐orientation system to obtain information from their surrounding environments, although further studies are needed to confirm this hypothesis.     

The vocal repertoire of chipmunks (Genus Eutamias) in California

A study of the vocalizations of chipmunks was conducted in the field and laboratory, utilizing sonagrams made from tape recordings, and observational data. Most observations were made on Eutamias townsendii, but interspecific variation in alarm calls was studied in all ten California species of Eutamias. The vocal repertoire of Eutamias includes several alarm calls: the chip, chuck, chippering, and in some species also the trill, and in others the whistle. Other calls include the agonistic chatter, courtship chatter, growl, and squeal. The chip is the most common call. There is consistent interspecific variation in structure and temporal arrangement of chips. Most of this variation correlates with body size.     

Male vocal imitation produces call convergence during pair bonding in budgerigars, Melopsittacus undulatus

The budgerigar, a small species of parrot, can learn new vocalizations throughout life and is therefore widely used as a model system for studying various aspects of vocal learning. It is not known, however, why parrots imitate sounds. To test the hypothesis that vocal imitation in budgerigars is related to pair bonding, we recorded approximately 100 contact calls from each of nine male and nine female adult budgerigars that were unfamiliar with one another and then placed them into pairs. We sampled their contact call repertoire weekly and conducted twice-weekly behavioural observation sessions. We compared contact calls by sonagram cross-correlation and classified them by means of a hierarchical clustering algorithm. This analysis showed that all pairs developed a shared call within an average of 2.1 weeks. Further analysis revealed that eight of the nine male budgerigars imitated the contact calls of their assigned mates, while none of the females imitated the calls of their males. We conclude that contact call imitation in adult budgerigars probably contributes to pair bond formation and maintenance. Prior studies on budgerigars were limited by the lack of a behavioural paradigm to elicit vocal imitation reliably. Our study remedies this and thereby serves as a foundation for future studies on vocal learning in adult animals. Copyright 2000 The Association for the Study of Animal Behaviour.     

VOCAL BEHAVIOUR AND CALL DEVELOPMENT IN THE BULLFINCH (PYRRHULA PYRRHULA)

ABSTRACT

A sonagraphic analysis of the vocalizations of bullfinches Pyrrhula pyrrhula is presented and their behavioural contexts and functions noted. The vocal repertoire of the bullfinch is compared to that of other finches with particular attention to repertoire size and sexual specificity; the repertoire of 14–17 vocal categories is comparatively greater than that of most carduelines and the majority of vocalizations were given by both sexes. The development of nestling, fledgling and some adult calls is described. Early vocal ontogeny in the bullfinch was similar to that previously described for the chaffinch. The earliest recorded calls of nestling bullfinches showed a single fundamental. The independent use of two sound sources became apparent on the second day after hatching and the major elements of the three best studied call types were all derived from the lower fundamental of the nestling begging call.     

Vocal Repertoire of Captive Capybara (Hydrochoerus hydrochaeris): Structure,Context and Function

In this work we describe the structure, behavioral context and functionality of the vocal repertoire of capybaras, a social Caviomorph rodent. Additionally, since territoriality is present in this species, we hypothesize the occurrence of vocal differences among social groups. We analyzed a total of 2069 calls emitted by 28 animals from three different social groups. The capybara’s repertoire is comprised by seven call types (whistle, cry, whine, squeal, bark, click and tooth‐chattering). The vocalizations were functionally categorized as contact, alarm, distress and agonistic calls considering their behavioral contexts. The click calls emitted by the adults of the three captive capybara groups were significantly different, confirming our hypothesis of social groups’ vocal differences. The richness of interactions mediated by vocalization in capybaras suggests that the species’ communication is an important mechanism to regulate social encounters and to alert members of the group about environmental cues.     

The use of Vocalizations of the Sambirano Mouse Lemur (<Emphasis Type="Italic">Microcebus sambiranensis</Emphasis>) in an Acoustic Survey of Habitat Preference

Primate vocalizations convey a variety of information to conspecifics. The acoustic traits of these vocalizations are an effective vocal fingerprint to discriminate between sibling species for taxonomic diagnosis. However, the vocal behavior of nocturnal primates has been poorly studied and there are few studies of their vocal repertoires. We compiled a vocal repertoire for the Endangered Sambirano mouse lemur, Microcebus sambiranensis, an unstudied nocturnal primate of northwestern Madagascar, and compared the acoustic properties of one of their call types to those of M. murinus and M. rufus. We recorded vocalizations from radio-collared individuals using handheld recorders over 3 months. We also conducted an acoustic survey to measure the vocal activity of M. sambiranensis in four forest habitat types at the study site. We identified and classified five vocalization types in M. sambiranensis. The vocal repertoires of the three Microcebus species contain very similar call types but have different acoustic properties, with one loud call type, the whistle, having significantly different acoustic properties between species. Our acoustic survey detected more calls of M. sambiranensis in secondary forest, riparian forest, and forest edge habitats, suggesting that individuals may prefer these habitat types over primary forest. Our results suggest interspecific differences in the vocal repertoire of mouse lemurs, and that these differences can be used to investigate habitat preference via acoustic surveys.     

Vocalizations of chicks and juveniles and the development of adult calls in the Aldabra White-throated rail Dryolimnas cuvieri aldabranus (Aves: Rallidae)

Calls were recorded from eggs, chicks and juveniles of the Aldabra White-throated rail Dryolimnas cuvieri aldabranus. A sonagraphic analysis was made of these calls, their behavioural contexts described and probable functions suggested. Three calls, the twitter, tiuu and contented peep were produced by chicks in the egg. All three calls may be derived from the basic peep first recorded some 36 hours before hatching. Shortly after hatching two more calls, the distress call and the alarm call, can be elicited from the rail chicks. Contented peeps and twitters are restricted to the repertoire of young rails. Song was first heard from wild rail chicks at the age of ten days and may develop from the contented peep. Three adult calls, the 'mp yeah, 'mptiuu and 'mpclick appear at the age of three months and six months later the adult vocal repertoire is completed by the appearance of 'mps, toks, purrs and nest-defence squeals. With the exception of the 'mp, all adult calls can be derived from the vocalizations of chicks and juveniles.     

Resting-Associated Vocalization Emitted by Captive Asian House Shrews (Suncus murinus): Acoustic Structure and Variability in an Unusual Mammalian Vocalization

Shrews have rich vocal repertoires that include vocalizations within the human audible frequency range and ultrasonic vocalizations. Here, we recorded and analyzed in detail the acoustic structure of a vocalization with unclear functional significance that was spontaneously produced by 15 adult, captive Asian house shrews (Suncus murinus) while they were lying motionless and resting in their nests. This vocalization was usually emitted repeatedly in a long series with regular intervals. It showed some structural variability; however, the shrews most frequently emitted a tonal, low-frequency vocalization with minimal frequency modulation and a low, non-vocal click that was clearly noticeable at its beginning. There was no effect of sex, but the acoustic structure of the analyzed vocalizations differed significantly between individual shrews. The encoded individuality was low, but it cannot be excluded that this individuality would allow discrimination of family members, i.e., a male and female with their young, collectively resting in a common nest. The question remains whether the Asian house shrews indeed perceive the presence of their mates, parents or young resting in a common nest via the resting-associated vocalization and whether they use it to discriminate among their family members. Additional studies are needed to explain the possible functional significance of resting-associated vocalizations emitted by captive Asian house shrews. Our study highlights that the acoustic communication of shrews is a relatively understudied topic, particularly considering that they are highly vocal mammals.     

Significance of temporal and spectral acoustic cues for sexual recognition in Xenopus laevis

As in many anurans, males of the totally aquatic species, Xenopus laevis, advertise their sexual receptivity using vocalizations. Unusually for anurans, X. laevis females also advertise producing a fertility call that results in courtship duets between partners. Although all X. laevis calls consist of repetitive click trains, male and female calls exhibit sex-specific acoustic features that might convey sexual identity. We tested the significance of the carrier frequency and the temporal pattern of calls using underwater playback experiments in which modified calls were used to evoke vocal responses in males. Since males respond differently to male and female calls, the modification of a key component of sexual identity in calls should change the male's response. We found that a female-like slow call rhythm triggers more vocal activity than a male-like fast rhythm. A call containing both a female-like temporal pattern and a female-like carrier frequency elicits higher levels of courtship display than either feature alone. In contrast, a male-like temporal pattern is sufficient to trigger typical male-male encounter vocalizations regardless of spectral cues. Thus, our evidence supports a role for temporal acoustic cues in sexual identity recognition and for spectral acoustic cues in conveying female attractiveness in X. laevis.     

A preliminary study of vocal communication in wild long-tailed macaques (Macaca fascicularis). I. Vocal repertoire and call emission

Vocal communication in wild long-tailed macaques (Macaca fascicularis) is described in terms of (1) a preliminary vocal repertoire and the situations in which calls occur in the natural habitat of this species and (2) quantitative measurement of the natural occurrence of calls in the field. Although a number of calls are relatively discrete (e.g., a male loud call), gradation is pronounced for both wide-spectrum (“harsh”) and narrow-spectrum (“clear”) vocal signals. Thirteen general types of harsh calls are identified provisionally as elements of the vocal repertoire. The exact number of discrete clear calls contributing to the vocal repertoire could not be ascertained precisely, but these calls were classified operationally into six broadly acoustically different classes in order to measure natural vocal behavior. Vocalizations tended to occur in temporal “clusters” during sample, periods. Narrow-band clear or “coo” calls were more frequently performed by macaques than wide-band harsh calls. The possible functional implications of the correlated occurrence of multiple vocal signals are discussed.     

Cooperatively breeding Arabian babblers call differently when mobbing in different predator-induced situations

Cooperatively breeding Arabian babblers (Turdoides squamiceps) havea repertoire of different calls that they use in predator-induced contexts.We investigated their vocal mobbing behavior in two different predator-inducedsituations. We presented territorial groups of babblers a perched,stuffed owl representing an avian predator and a cat representinga ground predator. Babblers approached in both situations andmobbed the predators with the same two call types. In both predator-inducedsituations their first call was a short, metallic-sounding "tzwick."In response to the cat, babblers continued to primarily usetzwicks. However, in continued response to the owl, the babblersprimarily used long trills. The experiments indicate that differencesin use of two common call types during mobbing provide informationon differences in predator-induced situations, although no calltype per se identified a specific situation. The experiments suggestthat the short tzwicks indicate a higher risk or urgency thantrills and that combinations of both call types may providegraded information about differences in predator-induced situations.The relatively stable groups of these cooperative breeders mighthave favored evolution for using different calls in differentmobbing situations.     

A field study on the vocalizations of Goeldi's monkeys (Callimico goeldii)

The vocalizations ofCallimico goeldii inhabiting North Bolivia were recorded and analyzed. A total vocal repertoire of 40, including two ultrasonic vocalizations, was recognized. The situation in which each vocalization was emitted is described. The phonetic structure of the longdistance location calls varied precisely dependent on the interindividual distances, while distinct individual variations were seen in the short-distance location calls. Every agonistic call could grade into another, from that reflecting the most aggressive tendency to that of fear emotion. The repertoire and characteristics of the infantile calls are also described, and their ontogeny is discussed.     

Age- and sex-specific patterns of vocal behavior in De Brazza's monkeys (Cercopithecus neglectus)

Although vocal production is strongly genetically determined in nonhuman primates, vocal usage is more likely to be influenced by experience. Nonetheless, sex differences in both production and usage can be found in the vocal repertoire of adults, but little attention has been paid to their ontogeny. Here, we provide the first comprehensive analysis of the vocal repertoire of De Brazza's monkeys (Cercopithecus neglectus), with particular attention to age- and sex-specific patterns. This species has special interest because it is the only monogamous species of guenons, but it nevertheless shares the strong sexual morphological and behavioral dimorphism seen in other guenons. A structurally based classification of calls recorded in 23 captive individuals has been cross-validated by an analysis of the associated contexts of emission. We identified sound units that could be uttered alone or concatenated to form 10 call types, including only three types shared by all age-sex-classes. Both age- and sex-discrepancy in terms of phonation could be explained by maturational changes and morphological dimorphism. In general, call production and usage parallel those seen in other guenons, suggesting that phylogeny and sexual dimorphism play important roles in vocal communication in this species. However, the boundary between adult male and female vocal repertoires appeared to be less strict than previously reported, suggesting that both sexes have the capacity to produce calls of the other sex but that social roles may constrain this expression. Similarly, age-specific vocal patterns would reflect respective social roles, and experience to some extent. Finally, calling rates would reflect age-/sex-specific degree of involvement in intragroup social networks. These findings highlight the relative importance of phylogeny, morphology, and social system on the shaping of individual repertoires in nonhuman primates.     

Biphonation May Function to Enhance Individual Recognition in the Dhole, Cuon alpinus

Biphonation (two independent fundamental frequencies in a call spectrum) represents one of the most widespread nonlinear phenomena in mammalian vocalizations. Recently, the structure of biphonations was described in detail; however, their functions are poorly understood. For the dhole (Cuon alpinus), biphonic calls represent a prominent feature of vocal activity. In this species, the biphonic call is composed of two frequency components – the high‐frequency squeak and the low‐frequency yap, which also occur alone as separate calls. In this study, we test the hypothesis that the complication of call structure, resulting from the joining of these calls into the biphonic yap–squeak may enhance the potential for individual recognition in the dhole. We randomly selected for analysis 30 high‐frequency squeaks, 30 low‐frequency yaps and 30 biphonic yap–squeaks per animal from five subadult captive dholes (450 calls in total). Discriminant analysis, based on 10 squeak parameter values, showed 80.7% correct assignment to a predicted individual. For 10 yap parameters, the correct assignment was only 44.7%. However, the analysis based on 10 parameters of the biphonic yap–squeak, selected as best contributing to discrimination, showed 96.7% correct assignment to a predicted individual. The results provide strong support for the hypothesis tested showing that the joining of two independent calls into a common vocalization may function to enhance individual recognition in the dhole.     

Horizontal transmission of vocal traditions in killer whale (<Emphasis Type="Italic">Orcinus orca</Emphasis>) dialects

Unlike most other mammals, killer whales are capable of vocal learning and learn the dialect of their natal pod from their mothers. The classical model of killer whale dialect development suggests that the repertoire of calls is learned only “vertically” from mother to offspring, and calls evolve gradually with time by random drift caused by the accumulation of copying errors. However, some observations suggest that not only “vertical” (from mother to offspring) vocal learning can occur in killer whales, but also “horizontal” (between adult animals). In this study we analyzed the distribution of different call types and similarity of calls from the same type in different pods of killer whales from Kamchatka waters to estimate the probability of existence of interpod horizontal transmission of vocal traditions in killer whales. We found that the degree of similarity of K1 calls and K5 calls in different pods can differ. This situation contradicts the classical hypothesis and is possible in two cases: if different call types change with various speed in different pods, or if horizontal transmission of call features takes place. The distribution of K4 and K10 call types across pods also suggests the existence of horizontal transmission: K4 calls occur in the dialects of five of ten pods, and K10 calls, in six of ten pods, but only one pod has both K4 and K10 calls. Our results suggest that the real picture of the distribution of call features and call types in killer whale dialects contradicts the classical hypothesis of killer whale dialect evolution through the accumulation of copying errors.     

白颊噪鹛四川亚种繁殖期鸣声声谱分析

2008年3～10月,在四川省南充市郊通过声谱分析对白颊噪鹛四川亚种Garrulax sannio oblectans繁殖期的鸣声与行为做了初步研究.其鸣声类型具有占区、驱赶、雌雄应答、求偶、交配、乞食、召唤、报警、惊叫及集群觅食等鸣声.其鸣声大多由短的重复的单音节、双音节和多音节鸣声组成.鸣声音节中最常见为单音节鸣声,最少的为多音节鸣声.