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Temporal patterning of recorded singing sessions of 26 different male ovenbirds Seiurus auricapillus (Fringillidae: Parulini) was analyzed computationally, in order to test whether differences among songs are potentially informative or merely reflect performance errors. Repeated songs within a singing session by a given male showed relatively little inter-individual variation in the duration of the song or in the number of units composing it, although these features varied substantially among individuals. On the other hand, within a session of singing by an individual male, the most variable and potentially informative aspect of temporal patterning was the relative placement of the peak amplitude within the song. These results support the hypothesis that diversity in the vocalization sessions of oscine passerines can be produced by other means than the use of a varied song repertoire, even in a species like the ovenbird that uses just one song type. Because variation among song was focused on a single feature, performance errors are an unlikely explanation, suggesting that the temporal patterning of singing sessions may play an informative role, such as the minimization of habituation on the part of receivers.

Domestication affects behavioral and vocal responses, involved in communication with humans; in particular, those that attract human attention. In this study, we found that silver foxes of Tame strain, experimentally domesticated for a few tenses generation, displayed bursts of vocal activity during the first minute after appearance of an unfamiliar human, that faded quickly during the remaining time of the test, when the experimenter stayed passively before the cage. Distinctively, foxes of Aggressive strain, artificially selected for tenses generations for aggressive behavior toward humans, and the control group of Unselected for behavior silver foxes kept steady levels of vocal activity for the duration of the tests. We found also that Aggressive foxes vocalized for a larger proportion of time than Unselected foxes for all five minutes of the test. We discuss the obtained data in relation to proposal effects of domestication on mechanisms directed to involving people into human-animal interactions and structural similarity between human laughter and vocalization of Tame foxes.

We investigated the effects of other's attentional states on vocalizations in monkeys. The subjects were 14 Japanese monkeys (Macaca fuscata), which vocalized spontaneously in the feeding context. In the initial experiment, an experimenter moved towards and away from the subject monkeys. The monkeys vocalized more frequently when the experimenter moved away rather than towards them. To examine the effects of the experimenter's body orientations and moving directions separately, additional experiments were conducted. When the experimenter stood facing towards and facing away from the subject monkeys, the monkeys vocalized more frequently when the experimenter stood facing away rather than facing towards. When the experimenter moved towards and away from the subject monkeys while facing them, the monkeys vocalized more frequently when the experimenter moved away from them rather than towards them. These results suggested that the monkeys vocalized more frequently when the situation changed to that where the monkeys were not likely get food from the experimenter. It seems that monkeys recognize the attentional states of others by body orientation and modify their vocalizing behavior accordingly.

Calls emitted by infants when the infant loses sight of its parents are useful to estimate the infant's requirement for parental care. When an Old World monkey infant loses sight of its mother it emits whistles. Therefore, it would be interesting to determine whether mothers could distinguish their own infant's whistles from the whistles of other infants. The response of each of seven Japanese macaque (Macaca fuscata) mothers to her own infant's whistle was compared with their responses to another infant's whistle. Matched control playback experiments were performed when the infants were four to six months old. The results showed that each mother could distinguish her own infant's whistle from that of another infant when the infants were four to six months old. Although a stricter experimental plan is required to further examine the issue, we found that the dominance rank of the infant's mother was another important factor in the female response to the infant's call. The finding suggests that females can associate a call emitted by an infant with its mother's rank, even before the infant begins to wander far from its mother.

Absolute pitch (AP) perception refers to the ability to identify, classify, and memorize pitches without use of an external reference pitch. In tests of AP, several species were trained to sort contiguous tones into three or eight frequency ranges, based on correlations between responding to tones in each frequency range and reinforcement. Two songbird species, zebra finches and white-throated sparrows, and a parrot species, budgerigars had highly accurate AP, they discriminated both three and eight ranges with precision. Relative to normally reared songbirds, isolate reared songbirds had impaired AP. Two mammalian species, humans and rats, had equivalent and weak AP, they discriminated three frequency ranges to a lackluster standard and they acquired only a crude discrimination of the lowest and highest of eight frequency ranges. In comparisons with mammals even isolate songbirds had more accurate AP than humans and rats.

Acoustic communication during courtship has been extensively studied in many Drosophila species. Here we summarise approaches that have been applied to the study of both song production and hearing. These approaches harnessed a variety of genetic tools available in Drosophila, such as isolation of song or hearing mutants, QTL mapping and transgenesis as well as electrophysiology and behavioural analysis. We also provide a short guide for the methodology used in acoustic studies in Drosophila and discuss prospects and new tools that would benefit future research.

Laying hens are thought to express an expectation of a rewarding event through a specific vocalisation, the gakel-call. It has been suggested that the gakel-call is related to frustration, i.e. the thwarting of behaviour. We investigated if frustrative nonreward (nonreinforcement in a situation that previously was consistently reinforcing) in laying hens is expressed through this gakel-call. Twenty hens of two commercial strains, ten ISA White Leghorn and ten ISA Brown Warren were subjected to a classical conditioning procedure. After 23 h of food-deprivation they were trained, in automated Skinnerboxes, to use red lights as a signal (unconditioned stimulus) for a food reward. After this the hens of each strain were equally divided into two groups of five. They were subjected to a control session (light as conditioned stimulus followed by food reward) and to a frustration session (conditioned stimulus followed by nonreward). Both during the frustration and control session behaviour and vocalisations were recorded. In the White Leghorn strain high levels of alarm-calls are found as indicators of anxiety. In the Brown Warren strain more gakel-calls and an increased locomotor activity are found after frustrative nonreward. In conclusion, both findings suggest that vocalisations could serve as indicators of a laying hen's welfare.

East African Guereza colobus monkey males are known for their conspicuous roaring behaviour; a spectacle that can dominate the predawn hours of African forests. Recent research has shown that these monkeys also produce roars during daytime hours in response to predators. While roars to leopards and eagles differ in how roaring phrases are assembled into sequences, there are no obvious structural differences between predawn roars and roars to eagles. Although recipients could use daytime information to disambiguate between the two contexts, this may be a risky strategy because eagles can be active before dawn. We carried out acoustic analyses, which showed that the duration of the first roaring phrase was significantly longer in predawn roars compared to eagle roars. Furthermore, the initial call repetition rate was faster in response to eagle roars compared to predawn roars. Apart from these two differences, all other acoustic characteristics were identical between the two contexts. Although these monkeys exhibit some of the most basic vocal behaviour found in non-human primates, callers are able to provide reliable contextual information by varying the duration and assemblage of individual vocal units. Playback experiments are needed to confirm whether recipients relate these acoustic differences to different contexts.

In the present study we explored whether dogs (Canis familiaris) are able to discriminate between conspecific barks emitted in different contexts recorded either from the same or different individuals. Playback experiments were conducted with dogs using barks as stimuli in a habituation-dishabituation paradigm. Barks were recorded in two contexts (stranger at the fence and when the dog was left alone) from different individuals. We found that dogs distinguished between barks emitted in these two contexts and were also able to discriminate between different individuals which were barking in the same context. These findings suggest that dog bark may carry context- and individual-specific information for the conspecifics.

Vermilion flycatchers (Pyrocephalus rubinus) vary their song rate and song length across the breeding season. Males sing more and longer songs after nest construction than before. Here we explored the possibility that this variation is meaningful to territorial males. Using a playback approach, we tested several males with different variations in song output (i.e. variations in song length and song rate) in different periods of the breeding season (i.e. before and after the onset of nest construction). We found that males call more in response to playbacks of long and short songs before the onset of nest construction. However, after nest construction began they responded flying more when exposed to long songs than to short songs. These results show that vermilion flycatcher discriminates between different variants of song length, and suggest that males react to long songs as if they were more threatening signals than short songs, especially after the onset of nest construction. We did not find evidence of males discriminating between a high and a low song rate. We discuss some possible implications for song function in this sub-oscine species, and compare these findings with other results in oscine species.

In this study we tested the often suggested claim that people are able to recognize their dogs by their barks. Earlier studies in other species indicated that reliable discrimination between individuals cannot be made by listening to chaotically noisy vocalizations. As barking is typically such a chaotic noisy vocalization, we have hypothesized that reliable discrimination between individuals is not possible by listening to barks. In this study, playback experiments were conducted to explore (1) how accurately humans discriminate between dogs by hearing only their barks, (2) the impact of the eliciting context of calls on these discrimination performances, and (3) how much such discrimination depends on acoustic parameters (tonality and frequency of barks, and the intervals between the individual barks). Our findings were consistent with the previous studies: human performances did not pass the empirical threshold of reliable discrimination in most cases. But a significant effect of tonality was found: discrimination between individuals was more successful when listeners were listening to low harmonic-to-noise ratio (HNR) barks. The contexts in which barks were recorded affected significantly the listeners' performances: if the dog barked at a stranger, listeners were able to discriminate the vocalizations better than if they were listening to sounds recorded when the dog was separated from its owner. It is rendered probable that the bark might be a more efficient communication system between humans and dogs for communicating the motivational state of an animal than for discrimination among strange individuals.

Results of this study indicate that in the Ortolan Bunting Emberiza hortulana, syllables of the same shape on sonograms (i.e. homologue syllables) often significantly differ between males in frequency parameters. Typically, homologue syllables of different males in the studied population had a similar bandwidth but shifted minimal and maximal frequencies. We found no strong evidence supporting that the frequency of homologue syllables is affected by the body size variation of males. Besides, frequency parameters of different song types within a male's repertoire did not correlate with each other. Moreover, we found that some males within the population sing two versions of apparently 'the same' song type, which differ in frequency parameters of syllables. Such different frequency versions were sung with eventual variety, which suggests that they are treated as different song types by birds. All these results support the idea that the fine acoustic structure of syllables (and song) is under a strong influence of the acoustic template (i.e. depend mainly on from whom the song was copied). We also found that the frequency of initial syllables within the song strophe is much more variable between males than in case of final syllables. Regardless of the great between-individual variation in initial syllable frequency, the syllables forming the final part of the song are kept within a very restricted bandwidth. These results support our earlier finding that strict syntactic rules of song formation exist in this species. These rules condition the acoustic variation of the initial and final part of the song. At least potentially, such a system enables species recognition and individual variation irrespective of repertoire level. Results of this study indicate that more attention should be paid to the problem of minimal units of song repertoire and to identity of such units within the bird population.

Previous animal research has traditionally used arbitrary stimuli to investigate timing in a temporal bisection procedure. The current study compared the timing of the duration of an arbitrary, auditory stimulus (a 500-Hz tone) to the timing of the duration of a naturalistic, auditory stimulus (a pigeon cooing). In the first phase of this study, temporal perception was assessed by comparing psychophysical functions for the duration of tone and cooing signals. In the first set of tests, the point of subjective equality (PSE) was significantly lower for the tone than for the cooing stimulus, indicating that tones were judged longer than equivalent durations of cooing. In the second set of tests, gaps were introduced in the tone signal to match those present in the cooing signal, and no significant difference in the PSE for the tone or the cooing signal was found. A repetition of the testing conducted with gaps removed from the tone signal, failed to replicate the difference in the PSEs for the tone and cooing signals originally obtained. In the second phase of the study, memory for the duration of tone and cooing was examined, and a choose-long bias was found for both signals. Based on these results, it appears that, for pigeons, there may be no significant differences in either temporal perception or temporal memory for arbitrary, auditory signals and more complex, naturalistic, auditory signals.

Rat pups emit broadband vocalizations with components extending from the audible to the ultrasonic range. Three experiments were undertaken to determine the circumstances under which the calls are emitted, and the effects that they might have on the maternal female's behavior. In the first study, pups were manipulated by the experimenter in several different ways. Broadband calling occurred when the pup was picked up and moved off the horizontal plane. In a second study, the mother was observed interacting with her litter. Vocalizations occurred most often when the mother engaged in behaviors that brought her into contact with the pups, such as nest entry, moving while in the nest, and pup licking. In another experiment, females were temporarily deafened. Relative to controls, deafened females engaged in more incidental contact with the pups, although only if the female was deafened during the first of two tests, when the pups were two days old. Broadband calling may function to reduce rough handling or inadvertent contact by the mother.

The present study compared the responses of adult domestic cocks and capons to a variety of novel and potentially frightening events. Cocks took longer to feed, spent less time feeding and ate less of their diet when it was dyed an unfamiliar colour than did capons. They also showed more pronounced avoidance of a novel object placed in the food trough. Conversely, cocks showed less behavioural inhibition than capons when placed individually in an unfamiliar pen (open field) containing a human observer: they ambulated sooner and more, and vocalized, pecked at the environment and flapped their wings more often. No significant differences were found between the tonic immobility fear reactions of cocks and capons. The pattern of results is considered more likely to reflect the stabilisation of attention by testosterone rather than any direct effect of the hormone on the ease of evocation and expression of fear.

Aptenodytes penguins have a recognition call consisting of a series of repeated syllables. Play-back experiments were conducted to determine the respective importance of the temporal pattern of syllables and the syllable structure. Two hybrid signals were created by switching the temporal pattern of the familiar call (partner or parent) with that of an alien call, then played back to relevant partners. The hybrid signal with the familiar temporal pattern of syllables and an alien syllable structure induced no response of individual recognition, while the hybrid signal with an alien temporal pattern of syllables and the familiar syllable structure elicited some positive responses.

Calls of Ctenodactylus gundi living in semi-natural conditions in our laboratory were recorded during various interactions : sexual, agonistic, maternal. The physical characteristics of the sounds lead us to describe five major structural groups and eleven vocal types. Two of them were recorded only in young animals. Intermediate calls and some complex sequences formed by association of two vocal types were observed. When emitting sounds, adult gundis can produce eight vocal sequences. In two of these phrases a constant association of two different calls can be shown. Seven sequences can be related to one of three kinds of social interactions : sexual intercourse, withdrawal or aggressivity. In each,vocal types are arranged in a gradual order based on the intensity of the interaction. The alarm call and two calls produced by young gundis when interacting with their mother must be added to the seven sequences described above. Gundi's calls appear then to be related both to the quality of social interactions and to the degree of arousal of the emitter. Functional problems are discussed and compared with available data from some other Rodents.

An experimenter induced tonic immobility (TI) in parentally naive chicks (G. gallus domesticus). The chicks remained in TI longer when they were exposed to a conspecific adult fear squawk alarm call than when exposed to an equally novel attraction call or white noise. In a second experiment, both aerial-predator and ground-predator alarm calls enhanced TI similarly to the fear squawk call which is elicited by capture. These results support the hypotheses that TI is an antipredator defense mechanism and that alarm calls evolved through kin-selection.

The purposes of this study were: to test whether male song birds could be trained to discriminate between a reference song type and a set of other types and to see if in learning the discrimination the birds had formed a category of "reference song" as opposed to "others". Three male great tits learned to discriminate between a reference song type (B) and 10 others. All of them showed an improvement with experience, although the final scores and consistency varied between individuals. In spite of the variability among birds some of the 10 song types were easier to discriminate from B than others. Two of the birds achieved at least 80% of discrimination, but only one of them yielded good data in the following categorization tests: In one session the bird was presented with 20 novel "other" song types and the same reference type B. This bird treated all 20 types as "others". Therefore, the bird appears to have formed the category "other". In two other sessions the bird was presented with 40 different versions of B (as classified by the authors) recorded from 40 different individual birds, and the same 10 training "others". The bird categorized 16 out of the 40 Bs as B, and overall discriminated significantly between Bs and the 10 other types. Therefore, this bird generalized the stimulus song B to other related stimuli. We conclude that, although our results are preliminary, they at least indicate a method of studying how birds categorize songs.

Vocalisation is important in the transmission of fear/alarm among chickens. In this experiment, therefore, the effects of various conspecific calls on tonic immobility, a fear-potentiated, anti-predator response, were examined in adult laying hens. The shortest durations of immobility were observed after exposure to recordings of either the familiar background noise of the poultry house of ‘Ku’ calls which are normally associated with feeding. These stimuli exerted similar effects and both are considered more likely to attenuate rather than heighten fearfulness. Intermediate levels of immobility followed presentation of the post-laying cackle whereas recordings of warning calls, such as the aerial predator call, the ground predator call or the fear squawk, all significantly prolonged tonic immobility. The biological significance of these results is discussed in terms of fear and predator-defence.

Captive black-capped chickadees (Parus atricapillus) were presented with normal (2-note) and lengthened (3-note) songs to investigate how note number and order are represented. Normal fee bee (FB) song was embedded in four different 3-note sequences containing an additional fee (F) or bee (B). Latency to vocalize after playback varied with the position, but not the type of added note, (i.e. slower responses to BFB and FFB than to FBF and FBB). Latency did not differ appreciably between normal (2-note) and these 3-note songs. The presence of normal 2-note song in each 3-note song may override note count. Our results provide further evidence that chickadees represent the absolute temporal location of the first, but not the last note of conspecific song.