Tuco-tucos’ vocalization output varies seasonally (<Emphasis Type="Italic">Ctenomys pearsoni</Emphasis>; Rodentia,Ctenomyidae): implications for reproductive signaling

Tuco-tucos are subterranean rodents endemic of South America. Ctenomys pearsoni is a solitary species from southwestern Uruguay. Each individual occupies its own burrow and aggressively defends it, except for juveniles before dispersing and couples during reproduction. We tried to understand how these animals find a partner and how they know their reproductive state, avoiding to spend excess energy burrowing to locate those partners for reproduction and avoiding above-ground predation. We studied a C. pearsoni population in the field from June 2005 until March 2007, using individually identified animals, some fitted with radio-tracking collars. For their long-range vocalizations, we recorded the number of vocalizations, number of series (groups of notes composing the vocalization) emitted, time of day of the emission, and emitter identity. Samples were taken by listening to the emissions. Results show that the number of emissions changes along the year, being higher during the reproductive season. Males emit more frequently than females and do it throughout the year. Female vocalizations rise in number when reproduction starts and then decline in number through pregnancy and/or until juveniles disperse and also vary in length being longer during the beginning of the breeding period. These results suggest that female vocalization (i.e., repetition and duration) would inform about emitter’s location, sex, and reproductive condition.     

鸟类鸣声与个体适合度关系的研究进展

鸣声蕴藏着丰富的生物学信息,是鸟类间信息交流最主要的方式之一.本文综述了鸟类鸣声行为与包括个体状态(体征、激素水平和健康状况)、社会等级及繁殖(性选择和成效)在内的个体适合度关系的研究进展.文章总结发现,鸟类的鸣声水平与单一体征参数关系的研究结果不稳定,鸣声可能受个体内部的多种激素调控,并与个体的社会等级有直接关系.雌...     

Communication and spatial relationships in a colony of common grackles

Most communication among common grackles Quiscalus quiscula occurs at distances of less than a few metres in the noisy environment of a breeding colony. This report examines both the adaptations of communication to these conditions and the effects of communication in regulating individuals' spatial relationships. For each of six vocalizations and five action patterns studied in one colony, I consider variation in the form of the display, the circumstances associated with its use, and the responses it elicits. Each individual, male or female, has one characteristic, stereotyped song pattern that would facilitate individual recognition between mates. Variation in the components of vocalizations and action patterns is of two kinds: unidimensional, with either covarying or nested components, or multidimensional, with independently varying components, alternatives that have different implications for communication. The wide-spectrum sounds made by common grackles offer advantages in close-range communication in colonies, because the ease of locating such signals would minimize the cocktail-party effect, although they would have disadvantages in long-range communication. Most vocalizations of common grackles lack associations with specific responses or external contexts, a situation that should often characterize short-range communication between acquainted individuals. The responses to vocalizations vary with context, especially the initial spatial relationships and identities of the interactors.     

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.     

High-Pitched Notes during Vocal Contests Signal Genetic Diversity in Ocellated Antbirds

Animals use honest signals to assess the quality of competitors during aggressive interactions. Current theory predicts that honest signals should be costly to produce and thus reveal some aspects of the phenotypic or genetic quality of the sender. In songbirds, research indicates that biomechanical constraints make the production of some acoustic features costly. Furthermore, recent studies have found that vocal features are related to genetic diversity. We linked these two lines of research by evaluating if constrained acoustic features reveal male genetic diversity during aggressive interactions in ocellated antbirds (Phaenostictus mcleannani). We recorded the aggressive vocalizations of radiotagged males at La Selva Biological Station in Costa Rica, and found significant variation in the highest frequency produced among individuals. Moreover, we detected a negative relationship between the frequency of the highest pitched note and vocalization duration, suggesting that high pitched notes might constrain the duration of vocalizations through biomechanical and/or energetic limitations. When we experimentally exposed wild radiotagged males to simulated acoustic challenges, the birds increased the pitch of their vocalization. We also found that individuals with higher genetic diversity (as measured by zygosity across 9 microsatellite loci) produced notes of higher pitch during aggressive interactions. Overall, our results suggest that the ability to produce high pitched notes is an honest indicator of male genetic diversity in male-male aggressive interactions.     

Behavioral Ecology of Elliot’s Laughingthrush (<Emphasis Type="Italic">Trochalopteron</Emphasis> (<Emphasis Type="Italic">Garrulax</Emphasis>) <Emphasis Type="Italic">elliotii</Emphasis>, Timaliidae,Aves): 2. Vocal Repertoire

Our work is the first study on the vocal repertoire of one of the babbler species, Elliot’s laughingthrush. Field studies were carried out in Hupingshan Nature Reserve, Hunan Province, China. There are three types of signals in the repertoire: songs, calls (chattering), and duets. Songs and calls are used by both males and females. The song consists of a quiet introduction (short note) and a louder main part (two or three tonal notes). There are up to four song variants in the repertoire of a given pair. All songs can be classified into three types. Types I and II represent songs with the main part consisting of three notes, while type III consists of two notes. Types I and II differ from each other in certain features of the frequency modulation shape of the first two notes. All song types can be used during the spontaneous vocalization of a single bird. However, their usage in other contexts differs. Songs of types I and II are more often uttered during vocal interactions of neighbor males. Songs of type III appear to be characteristic of male–female duets. Chattering (calls) is a continuous series of broadband notes. There are several (two to five) note variants in each series. Chattering can be used both during a male–female interaction and as an alarm call. We found an inverse correlation between (1) the duration of pauses between notes, and (2) the number of note variants (“repertoire size”) in a series. Both parameters probably reflect the internal state of an individual at a given moment.     

Maternal vocalizations of mallard ducks (Anas platyrhynchos)

While incubating, brooding and calling their young out of the nest, female mallard ducks (Anas platyrhynchos) utter a species-typical maternal vocalization that their young find highly attractive. To determine the characteristic acoustic features of these calls, we recorded the vocalizations of seven hens in the field. The pre-exodus and nest exodus calls of these hens were similar with respect to frequency modulation, presence of a low-frequency impulsive sound, note duration, and repetition rate. The exodus call differs from the pre-exodus call in having more notes per burst and more harmonics, with a corresponding upward shift in dominant frequency. Repetition rate and frequency modulation may be the critical acoustic features of the auditory basis of species identification in mallard ducklings.     

White Ibis integument color during the breeding season

ABSTRACT.   Many birds undergo bare part color changes during the breeding season. Most investigators have focused on color as a signal of individual quality. An alternative, but not exclusive, function of bare part color may be signaling readiness to breed, especially in colonial, asynchronous breeders. White Ibises ( Eudocimus albus ) are colonial waterbirds that show vivid bare part colors on their bills and legs during reproduction. We quantified bill and leg colors to describe color changes and their possible relationship to reproductive status during the breeding season of White Ibises in the Florida Everglades from 1998 to 2001. We also examined the correlation between bare part colors and circulating concentrations of sex steroids to understand the factors that regulate bare part colors. During the display stage, male and female ibises developed dark pink bills and scarlet legs. As the breeding season progressed, bills and legs faded and developed a muted pink hue. The bare part colors of female ibises were correlated with testosterone concentrations, but those of male ibises were not correlated with any hormones. A discriminant function analysis based on principal component scores (representing variation in saturation and hue) and the amount of black on the bill successfully classified ibis reproductive stage 94% of the time. The use of bare part colors to determine reproductive status may be useful for studying reproduction in colonially nesting birds, where access to breeding sites can be difficult and potential for researcher disturbance is high.     

Communication at the Garden Fence – Context Dependent Vocalization in Female House Mice

House mice (Mus musculus) live in social groups where they frequently interact with conspecifics, thus communication (e.g. chemical and/or auditory) is essential. It is commonly known that male and female mice produce complex vocalizations in the ultrasonic range (USV) that remind of high-pitched birdsong (so called mouse song) which is mainly used in social interactions. Earlier studies suggest that mice use their USVs for mate attraction and mate choice, but they could also be used as signal during hierarchy establishment and familiarization, or other communication purposes. In this study we elucidated the vocalization behaviour of interacting female mice over an extended period of time under semi-natural conditions. We asked, if the rate or structure of female vocalization differs between different social and non-social contexts. We found that female USV is mainly used in social contexts, driven by direct communication to an unknown individual, the rate of which is decreased over time by a familiarization process. In addition we could show that female mice use two distinct types of USVs, differing in their frequency, which they use differently depending on whether they directly or indirectly communicate with another female. This supports the notion that vocalization in mice is context dependent, driven by a reasonable and yet underestimated amount of complexity that also involves the interplay between different sensory signals, like chemical and auditory cues.     

Individual and geographical variation in display behaviour of male harbour seals in Scotland

Studying variations in behaviour at the individual or population level enables insight into the reproductive strategies within a species. We examined individual and geographical variation in the vocal and dive behaviour of male harbour seals, Phoca vitulina, which is associated with aquatic mating. This display behaviour was recorded in the Moray Firth, Scotland, from July 1994 to 1997, and in Orkney, Scotland, during July 1998. One vocalization type was apparent in the Moray Firth and two in Orkney. Time parameters (total and pulse duration) varied between males in the population in the Moray Firth. We used both frequency and time parameters in a discriminant analysis, which showed that 73.2% of individual male vocalizations could be correctly classified; 94.6% of male vocalizations from the Moray Firth and Orkney could be correctly classified according to their geographical areas. Therefore, vocal variation was greater between geographical areas than between individuals. No individual variation was apparent between dive and surface interval durations. However, individuals varied significantly in the percentage of short surface intervals. Male harbour seals showed substantial variability in the parameters affecting their vocal and dive behaviour during the mating season. We suggest that these variations may be indicative of adaptations to varying environmental challenges influencing the reproductive strategies of discrete populations. Copyright 2000 The Association for the Study of Animal Behaviour.     

Call Learning in Black-capped Chickadees (Parus atricapillus): The Role of Experience in the Development of ‘Chick-A-Dee’ Calls

The role of learning in the development of bird vocalizations other than territorial song is not well studied. The well-known role of direct imitation in the development of territorial song potentially masks the effects of other processes in the development of vocal behaviour. The ‘chick-a-dee’ call of black-capped chickadees is a good system in which to investigate more subtle developmental processes because this call is composed of a small number of distinctive note types. These note types may be classified objectively based on a simple set of acoustic variables, allowing for a quantitative assessment of vocal learning. We raised four groups of black-capped chickadees under different degrees of social and acoustic isolation. We then used a multivariate analysis of the acoustic structure of the introductory call notes (‘A-’ ‘B-’ and ‘C-notes’) to determine how similar the notes produced by these hand-reared birds were to the notes of wild birds. Hand-reared chickadees with greater exposure to normal phonology produced notes of all three note types that were more similar to those of wild birds. Regardless of experience, however, all birds produced A-notes that fell within the normal range of those produced by wild birds. By contrast, the development of normal B- and C-notes appears to be more dependent upon experience. These data suggest that learning may play a different role in the development of different phonological units within one vocalization. Our results also illustrate the importance of considering processes other than simple imitation in the development of avian vocalizations.     

Human Classification of Context-Related Vocalizations Emitted by Familiar And Unfamiliar Domestic Cats: An Exploratory Study

ABSTRACT

Previous research has shown that human classification of contextspecific domestic cat “meow” vocalizations is relatively poor, although improves with experience and/or general affinity to cats. To investigate whether such classification further improves when recipients (humans) of the vocalizations reside with the vocalizing animal (cat), cat owners (n=10) were asked to listen to eight audio recordings of a single meow (4 from their own cat and 4 from an unfamiliar cat) produced during one of four possible contexts, and identify the context in which each meow was emitted. Contexts comprised food preparation, food-withholding, negotiating a barrier, and attention solicitation. In addition, participants were asked to rate 20 meow vocalizations (produced by unfamiliar cats in the four contexts) on scales measuring pleasantness and urgency, in order to investigate whether participants reached consensus on the emotional content of the vocalizations. Successful identification of both the context and the hypothesized emotional content of the vocalization would comprise the first steps in our understanding of whether human-directed cat “meow” vocalizations are fully advantageous. Forty percent of the participants identified the correct contexts at a level greater than chance when the vocalizations belonged to their own cat. However, no participants performed above chance when vocalizations belonged to an unfamiliar cat. Participants’ urgency ratings were not significantly influenced by the context in which the vocalization was produced. Pleasantness ratings, however, were significantly higher for the context of negotiating a barrier in comparison with attention solicitation. These results suggest that the domestic cat, as a species, does not have a context-specific repertoire of human-directed vocalizations. Successful context classification of cat meows however, was possible for some owners. Whether such success was due to individual learning ability or recognition of hypothesized emotional content of the call requires further investigation.     

“Girney” vocalizations among Japanese macaque females: Context and function

One vocalization in the Japanese macaque (Macaca fuscata) system of communication is the “girney.” Previous studies indicated that the “girney” is used for short range communication and that it tends to occur when subordinate animals approach and groom dominant ones and when females without infants approach females who have infants. Data were collected on the social behavior of adult female Japanese monkeys of the Arashiyama-A troop in Texas in order to test those results. The study indicates that “girneys” are the most frequently occurring vocalizations of females during and following the birth season and that they occur primarily in two contexts. Those are the proximity of a female to another female with a new infant and the proximity of a lower ranking animal to a higher ranking one. The contexts are ones in which the risk of aggression is high, and the “girneys” appear to function as appeasement gestures to reduce the risk.     

A study of the seasonal booming activity of the Bittern Botaurus stellaris; what is the biological significance of the booms?

Booming activity was studied in five focal male Bitterns Botaurus stellaris at two different marshlands of central Italy. For each individual, the length of the booming season, the seasonal and evening pattern of booming rate, the seasonal pattern of booming effort and some characteristics of the boom "trains" (sequences of calls) were studied. The lack of a common pattern of vocalization was noted, while the booming males showed individual patterns with regard to all the above characteristics. The length of the booming season and the booming effort differed at the two sites. While one bird was unique with respect to the quality of the vocalizations, a common characteristic of the remaining four focal birds was a marked increase or resurgence in booming activity in a period of the breeding season which coincided with the presence of the nestlings. Mainly on the basis of this particular seasonal vocalization pattern, we discuss the possible meaning of the booming activity of the male Bittern. One function of the booming activity suggested is the defence of a feeding territory, where the females of the booming male can find food to feed the nestlings. For the male, this appears to be his only contribution to the rearing of the offspring.     

Duets in Yellow-Naped Amazons: Variation in Syntax, Note Composition and Phonology at Different Levels of Social Organization

Complex vocal signals composed of multiple notes are used by many species. Such signals may vary in a number of features such as the rules that govern note order and timing (syntax), the relative number and types of different notes (note composition), and the acoustic structure of notes (phonology). Previous research examining male song in songbirds typically has shown greater conservation of syntax than phonology. Here we investigated whether these patterns of variation are also found in the duets of parrots. We examined geographic variation in the pair duets of yellow-naped amazons, Amazona auropalliata , at five sites within one vocal dialect. We also examined variation at several levels of social organization, including within pairs, among pairs and among sites, to assess where variability was greatest. Variation was highest at the within-pair level, although variation was also present at all other levels and for all of the duet factors. We hypothesize that variation at the among-site level allows duets to indicate site membership, while variation at the within-pair level allows pairs to change their duet to match their current social or physical environment. Syntax and phonology are also more conserved than note composition for all levels of social organization. This pattern may result because note composition is less important in duet function than syntax or phonology, or because development of syntax and phonology is more heavily influenced by genetic templates.     

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.     

Singing in the Face of Danger: the Anomalous Type II Vocalization of the Splendid Fairy-Wren

Males of certain species of fairy-wrens (Aves: Maluridae) emit a unique vocalization, the Type II vocalization, in response to the calls of potential predators. We conducted field observations and playback experiments to identify the contexts in which the Type II vocalization is emitted by splendid fairy-wren ( Malurus splendens ) males, and to examine social and genetic factors that influence its occurrence. In field observations and controlled playback experiments, Type II vocalizations were elicited most consistently by calls of the predatory gray butcherbird ( Cracticus torquatus ). Some vocalizations from other avian species also elicited Type II vocalizations, and the majority of these were vocalizations from avian predators. Splendid fairy-wrens are cooperative breeders, and males that responded with Type II vocalizations to playbacks of butcherbird calls tended to be primary rather than secondary males, had larger cloacal protuberances, and were older than those that did not respond. In addition, secondary males that were sons of resident females were more likely than non-sons to respond with a Type II vocalization. In another playback experiment, females responded similarly to the Type I song and Type II vocalizations of their mates. Although the Type II vocalization is emitted primarily in response to predator calls, it is inconsistent with an alarm call explanation. Patterns of reproductive success among Type II calling males suggest that it does not function as an honest signal of male quality. At present, the function of the vocalization remains anomalous, but indirect fitness benefits may play a role in its explanation.     

Development of Early Vocalizations and the Chick-a-dee Call in the Black-capped Chickadee,Parus atricapillus

The chick-a-dee call of the black-capped chickadee (Parus atricapillus) is composed of discrete elements, or notes, that are combined to form hundreds of different calls. To investigate the development of this complex call, 12 families of color-marked chickadees were observed and recorded in the wild. Vocalizations were monitored for 18 d in the nest and 14–18 d postfledging. Most vocalizations of nestlings and fledglings were associated with feeding. At hatching, vocalizations consisted of a structurally simple note type that became more complex and variable with age. Around 9–12 d, the development of the call occurred, when single notes became organized into a multiple-note unit. Notes within the call differentiated into higher frequency, rapidly modulated initial note types and a lower frequency, moderately modulated terminal note type, features also present in adult chick-a-dee calls. Several adult-like calls including chick-a-dee calls, fee-bee songs, and a subsong-like vocalization developed prior to fledgling dispersal. Based on resemblances of note structure and general call structure, the chick-a-dee call appeared to develop from calls of nestlings and fledglings, although not necessarily in a chronologically linear progression. Some features of the chick-a-dee call closely resembled features of older nestling and fledgling calls, while other features more closely resembled the sounds of very young nestlings. Vocal development in the chickadee is compared with song and call development in other species, and the possible significance of acoustic resemblances between chick-a-dee calls and the food-associated calls of nestlings and fledglings is discussed.     

Female presence and estrous state influence mouse ultrasonic courtship vocalizations

The laboratory mouse is an emerging model for context-dependent vocal signaling and reception. Mouse ultrasonic vocalizations are robustly produced in social contexts. In adults, male vocalization during courtship has become a model of interest for signal-receiver interactions. These vocalizations can be grouped into syllable types that are consistently produced by different subspecies and strains of mice. Vocalizations are unique to individuals, vary across development, and depend on social housing conditions. The behavioral significance of different syllable types, including the contexts in which different vocalizations are made and the responses listeners have to different types of vocalizations, is not well understood. We examined the effect of female presence and estrous state on male vocalizations by exploring the use of syllable types and the parameters of syllables during courtship. We also explored correlations between vocalizations and other behaviors. These experimental manipulations produced four main findings: 1) vocalizations varied among males, 2) the production of USVs and an increase in the use of a specific syllable type were temporally related to mounting behavior, 3) the frequency (kHz), bandwidth, and duration of syllables produced by males were influenced by the estrous phase of female partners, and 4) syllable types changed when females were removed. These findings show that mouse ultrasonic courtship vocalizations are sensitive to changes in female phase and presence, further demonstrating the context-sensitivity of these calls.