Vocal Communication in Pigs: Who are Nursing Piglets Screaming at?

Vocalizations during competition among nursing piglets were studied to investigate their possible effects, functions and implications for welfare. In Expt 1, two experimental piglets in each of 14 litters were temporarily deprived of milk by covering their preferred teats on the sow's udder. These piglets spent more time away from their teats than two control piglets, and vocalized frequently in the 2 min before milk ejection. Frequency of vocalization showed no consistent change over time within nursings; nor did it change in successive nursings despite the fact that hunger presumably increased. In Expt 2, tape recordings of intense vocalizations (screams) produced by piglets competing at the udder were played to 22 litters while they were nursing; each litter was played its own recording, a recording from another litter and silence as a control. Of 51 nursings analysed, 14 were terminated without milk ejection, all during playbacks. When the sow did nurse successfully during a playback, nursing was shorter (138 s) than during the silent controls (179 s). Both these responses by the sow might be expected to advance the next nursing. Piglets rarely showed any apparent response to screaming either from their littermates or from the loudspeaker. These results suggest that the calls function mainly as a signal to the sow that some piglets are being excluded from the current nursing episode.     

Is the Capacity for Vocal Learning in Vertebrates Rooted in Fish Schooling Behavior?

The capacity to learn and reproduce vocal sounds has evolved in phylogenetically distant tetrapod lineages. Vocal learners in all these lineages express similar neural circuitry and genetic factors when perceiving, processing, and reproducing vocalization, suggesting that brain pathways for vocal learning evolved within strong constraints from a common ancestor, potentially fish. We hypothesize that the auditory-motor circuits and genes involved in entrainment have their origins in fish schooling behavior and respiratory-motor coupling. In this acoustic advantages hypothesis, aural costs and benefits played a key role in shaping a wide variety of traits, which could readily be exapted for entrainment and vocal learning, including social grouping, group movement, and respiratory-motor coupling. Specifically, incidental sounds of locomotion and respiration (ISLR) may have reinforced synchronization by communicating important spatial and temporal information between school-members and extending windows of silence to improve situational awareness. This process would be mutually reinforcing. Neurons in the telencephalon, which were initially involved in linking ISLR with forelimbs, could have switched functions to serve vocal machinery (e.g. mouth, beak, tongue, larynx, syrinx). While previous vocal learning hypotheses invoke transmission of neurons from visual tasks (gestures) to the auditory channel, this hypothesis involves the auditory channel from the onset. Acoustic benefits of locomotor-respiratory coordination in fish may have selected for genetic factors and brain circuitry capable of synchronizing respiratory and limb movements, predisposing tetrapod lines to synchronized movement, vocalization, and vocal learning. We discuss how the capacity to entrain is manifest in fish, amphibians, birds, and mammals, and propose predictions to test our acoustic advantages hypothesis.     

Vocal individuality and rhythm in male and female duet contributions of a nonhuman primate

Duetting,or the stereotypical,repeated and often coordinated vocalizations between 2 individuals arose independently multiple times in the Order Primates.Across primate species,there exists substantial variation in terms of timing,degree of overlap,and sex-specificity of duet contributions.There is increasing evidence that primates can modify the timing of their duet contributions relative to their partner,and this vocal flexibility may have been an important precursor to the evolution of human language.Here,we present the results of a fine-scale analysis of Gursky’s spectral tarsier Tarsius spectrumgurskyae duet phrases recorded in North Sulawesi,Indonesia.Specifically,we aimed to investigate individual-level variation in the female and male contributions to the duet,quantify individual-and pair-level differences in duet timing,and measure temporal precision of duetting individuals relative to their partner.We were able to classify female duet phrases to the correct individual with an 80%accuracy using support vector machines,whereas our classification accuracy for males was lower at 64%.Females were more variable than males in terms of timing between notes.All tarsier phrases exhibited some degree of overlap between callers,and tarsiers exhibited high temporal precision in their note output relative to their partners.We provide evidence that duetting tarsier individuals can modify their note output relative to their duetting partner,and these results support the idea that flexibility in vocal exchanges—a precursor to human language—evolved early in the primate lineage and long before the emergence of modern humans.     

Wild Chimpanzees Produce Group‐Specific Calls: a Case for Vocal Learning?

Vocal learning, where animals can modify the structure of their vocalizations as a result of experience, has been found in a range of birds and mammals. Although vocal learning is a fundamental aspect of developing spoken language, there is as yet little evidence that vocal learning occurs in primates. Here we examine whether vocal learning may occur in chimpanzees. We analysed whether wild male chimpanzees, Pan troglodytes verus, of four communities living in a similar habitat in the Taï Forest, Côte d'Ivoire, developed community specific pant hoots. If so, we expected males of three contiguous communities to have distinct pant hoots, while pant hoots of males from a fourth, distant community, located 70 km away, should only differ from those of the contiguous communities by chance. Our analysis confirmed these expectations. In addition, the acoustic distances between the pant hoots of pairs of individuals did not correlate with the genetic relatedness of those pairs, where genetic relatedness was determined using nuclear DNA analysis. Thus, neither habitat nor genetic differences accounted for the observation that there were acoustic differences in the pant hoot structure of males living in neighbouring communities, but not in those of males from a distant community. This suggests that chimpanzees may actively modify pant hoots to be different from their neighbours, providing support for the vocal learning hypothesis.     

Vocal negotiation over parental care? Acoustic communication at the nest predicts partners' incubation share

In species with biparental care, individuals adjust their workload to that of their partner to either compensate or match its investment. Communication within a pair might be crucial for achieving this adjustment. Zebra finches, Taeniopygia guttata, form life‐long monogamous pair bonds, in which partners are highly coordinated and both incubate the eggs. When relieving each other during incubation, partners perform a structured call duet at the nest. If this duet functions to coordinate incubation workload, disrupting the pair's usual nest‐relief pattern by delaying the male's return to the nest should affect the structure of the duet. Using domesticated birds breeding in a large aviary, we found that delaying the male's return induced shorter duets with higher call rates. In addition, we tracked the location of individuals with a transponder at the nest and the feeder, and showed that these accelerated duets were associated with an increased haste of the partners to take turns incubating and foraging. Females also spent less time incubating during their subsequent shift, and females' time off‐nest was best predicted by their mate's calling behaviour in the previous duet. Taken together, these results suggest that duets may function as ‘vocal negotiation’ over parental care.     

Sex and Status Effects on Primate Volubility: Clues to the Origin of Vocal Languages?

Natural human languages are predominantly vocal. This suggests that, during evolution, speech may have enhanced the efficiency, utility, or flexibility of previous vocal behaviors. If so, there may be parallels between certain aspects of the vocalization patterns of human and nonhuman primates. The literature on humans contains evidence for greater frequency of vocalization, or volubility, between female–female than male–male dyads, and greater volubility among individuals of higher than lower social rank or status. We analyzed two classes of vocalization in free-ranging vervet monkey infants. In both classes, females vocalized significantly more often than males, and high-ranking animals were more voluble than mid- and low-ranking animals. If these findings are confirmed in primates other than vervets, it is conceivable that the voice contributes to the solution of some pan-primate problems, offering clues to the vocal bias in human languages.     

Vocal Communication in a Fission-Fusion Society: Do Spider Monkeys Stay in Touch With Close Associates?

In fission-fusion societies, in which animals from the same group may spend long periods of time apart from each other, individuals could use long-distance vocalizations to maintain contact with others. This could be achieved with vocalizations that simply carried information about the caller's identity and location. I explored this possibility using observations and experiments from a 3-year field study of spider monkeys (Ateles geoffroyi) in Punta Laguna, México, analyzing the use of the species' most frequent vocalization, the whinny. By following 2 subgroups simultaneously, I found that subgroups that were within the active space of the whinny approached each other more often than subgroups that were farther apart. Individual adults in these subgroups also emitted more whinnies when they were within hearing range of another subgroup than when farther apart. I used a paired playback design to determine whether whinnies could influence the behavior of close associates as opposed to nonassociated individuals. Although nonassociates were as likely as close associates to respond vocally to playbacks of whinnies, only a close associate ever approached the speaker. Collectively, the results suggest that whinnies are used by spider monkeys to achieve flexibility in spacing while maintaining specific social relationships.     

Vocal Plasticity – are Pied Flycatchers,Ficedula Hypoleuca,Open‐Ended Learners?

In some songbird species, large song repertoires are advantageous in female attraction, whereas song sharing with neighbours may give an advantage in male–male competition. Open‐ended learners, with the ability to memorize new song elements throughout their lives, may learn from territorial neighbours and thus benefit from increasing both repertoire size and song sharing. A distinction needs to be made between true adult song learning, i.e. memorization of novel song elements, and vocal plasticity resulting in changes in the use of previously memorized elements, such as the use of hidden repertoires or increased production of previously rare syllable types. We assessed the ability of adult pied flycatcher Ficedula hypoleuca males to learn previously unheard song elements and to change their song production in response to playback of unfamiliar, conspecific song, emulating a singing neighbour. After a 1‐week playback treatment, three out of 20 subjects had learned foreign song elements, providing evidence from the wild that pied flycatchers are true open‐ended learners. However, the syllable sharing with the playback stimulus repertoires had not changed, and the males’ repertoires had decreased rather than increased. Hence, we did not find support for increased syllable sharing with neighbours or increased repertoire size as functions of adult song learning in pied flycatchers. Because pied flycatcher song seems to serve mainly for mate attraction, copying of attractive syllable types is a possible alternative function of adult song learning in this species.     

Linking Social and Vocal Brains: Could Social Segregation Prevent a Proper Development of a Central Auditory Area in a Female Songbird?

Direct social contact and social interaction affect speech development in human infants and are required in order to maintain perceptual abilities; however the processes involved are still poorly known. In the present study, we tested the hypothesis that social segregation during development would prevent the proper development of a central auditory area, using a "classical" animal model of vocal development, a songbird. Based on our knowledge of European starling, we raised young female starlings with peers and only adult male tutors. This ensured that female would show neither social bond with nor vocal copying from males. Electrophysiological recordings performed when these females were adult revealed perceptual abnormalities: they presented a larger auditory area, a lower proportion of specialized neurons and a larger proportion of generalist sites than wild-caught females, whereas these characteristics were similar to those observed in socially deprived (physically separated) females. These results confirmed and added to earlier results for males, suggesting that the degree of perceptual deficiency reflects the degree of social separation. To our knowledge, this report constitutes the first evidence that social segregation can, as much as physical separation, alter the development of a central auditory area.     

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.