Pair Duets in the Yellow-Naped Amazon (Psittaciformes: Amazona auropalliata): Responses to Playbacks of Different Dialects

Yellow-naped amazons, Amazona auropalliata , have regional dialects in which several functional classes of vocalization, including contact calls and pair duets, change their acoustic structure at the same geographic boundaries. Here we examine the responses of 11 pairs of yellow-naped amazons to playbacks of duets from other pairs nesting near the same roost, other roosts within the same dialect, and roosts in foreign dialect areas. Overall, pairs responded more strongly to duets from their own dialect than to those of the foreign dialect. Pairs responded to both treatments from their own dialect (local same dialect and distant same dialect) with movement towards the broadcasting loudspeaker and more rarely with squeals, a vocalization typically observed only in the context of aggressive chases. These aggressive responses were never observed during playbacks of the foreign dialect treatment or congeneric controls. There were no differences among treatments in the incidence of contact calls or pair duets. A similar pattern of stronger aggressive responses to local than to foreign dialects has been found in a wide range of oscine songbirds. The results of the present experiment suggest that a general function may underlie this behavioral response both in oscines and in other bird taxa with vocal learning.     

Winter dialects in the bronzed cowbird and their relationship to breeding-season dialects

Studies of geographical variation in animal signals generally focus on breeding-season behaviour but, in many species, signalling persists throughout the year. In passerine birds, patterns of variation in the nonbreeding season might provide opportunities for vocal learning that have been neglected by a historic focus on breeding-season behaviour. This study provides the first example of dialect variation outside of the breeding season. Quantitative analysis of acoustic similarity showed discrete differences between the songs of bronzed cowbirds, Molothrus aeneus, in four winter flocks. Most songs produced by members of a given flock were classified as belonging to the same dialect. Songs from one of the four winter dialects were indistinguishable from songs recorded in the breeding season in the same region. Depending on migratory patterns, dialects in one season may be a consequence of dialects in the other season, or the two seasonal patterns may be the result of independent social or evolutionary forces. Because the nonbreeding season is an important period of vocal learning in some bird species, winter dialects might limit the range of signals available for individuals to learn to produce. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

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.     

Detailed large‐scale mapping of geographical variation of Yellowhammer Emberiza citrinella song dialects in a citizen science project

Song dialects, as a special case of geographical variation in vocalization, are useful tools in the study of a number of topics ranging from cultural evolution to the emergence of reproductive barriers, and thus continue to be the focus of many bird‐song studies. The Yellowhammer Emberiza citrinella is a common Palaearctic bird with a long breeding season and song period, whose distinctive song exhibits clearly distinguishable dialects differing in the composition of the final phrase. The species is therefore particularly suitable for large‐scale studies of dialect distribution involving not only experts but also members of the public. Here we demonstrate that citizen science can indeed allow mapping of songbird dialect distribution on a national scale in unprecedented detail. During the project Dialects of Czech Yellowhammers, which collected almost 4000 recordings over 6 years (2011–2016), we obtained information on dialect distribution for almost 90% of the territory of Czechia. We detected most of the common dialect types known elsewhere in Europe, and these were distributed in a fragmented fashion, with several unusual and rare dialects also detected in small areas. However, the highly scattered distribution of birds using some final phrases traditionally assigned to distinct dialects suggests that classification of Yellowhammer dialects warrants a thorough re‐assessment based on quantitative data. Successful involvement of the public in this and other ongoing citizen science projects has contributed to the establishment of the Yellowhammer as a model species for dialect research. The dataset will serve as a foundation for future studies investigating processes responsible for the origin and maintenance of avian dialects, and may be particularly useful for evaluating their spatial and temporal stability.     

Evidence for Vocal Learning and Limited Dispersal as Dual Mechanisms for Dialect Maintenance in a Parrot

Studies of avian vocal dialects commonly find evidence of geographic and acoustic stability in the face of substantial gene flow between dialects. The vocal imitation and reduced dispersal hypotheses are alternatives to explain this mismatch between vocal and genetic variation. We experimentally simulated dispersal in the yellow-naped amazon (Amazona auropalliata) by moving individuals within and across dialect boundaries in Costa Rica. One juvenile translocated across dialect boundaries altered its contact call to imitate the acoustic form of the local call six weeks post-release. In contrast, four adults translocated across dialect boundaries returned to their original capture site within 120 days, while five cross-dialect translocated adults who remained at the release site did not alter their contact calls. Translocated individuals were observed to show some segregation from resident flocks. The observation of vocal imitation by the juvenile bird supports the vocal imitation, whereas the behavior of adults is more consistent with the reduced dispersal hypotheses. Taken together, our results suggest that both post-dispersal learning by juveniles and high philopatry in adults could explain the stability of vocal dialects in the face of immigration and gene flow.     

Song overproduction, selective attrition and song dialects in the white-crowned sparrow

Male Puget Sound white-crowned sparrows, Zonotrichia leucophrys pugetensis, form large vocal dialects along the Pacific northwest coast of North America. Most adult males sing a single song dialect throughout their lives. To determine how dialects are maintained in this species, I studied two populations at the Columbia River mouth in a contact zone between two dialects. Singers of each of the two dialects clustered together in space, forming local song 'neighbourhoods'. Two hypotheses for the maintenance of dialects were tested. The late acquisition hypothesis predicts that yearling or adult male immigrants memorize their song from the territory neighbours they settle next to. The selective attrition hypothesis predicts that males memorize a variety of dialects early in life, overproduce song dialects upon arrival, and later selectively retain the one prelearned dialect that best matches what their neighbours sing. In 1997 and 1998, 35-40% of new territory occupants sang two dialects upon arrival in April, and then over the course of days to several weeks, discarded one dialect from their repertoire. Fourteen of 16 (88%) kept as their adult song the dialect that matched the dialect sung by the majority of their neighbours. No male added a new dialect to his repertoire after arrival, nor did males alter their retained dialect to more closely resemble their neighbours' songs. New arrivals that overproduced dialects upon arrival were significantly more likely to match their neighbours' dialect than males that did not overproduce upon arrival. In a playback experiment, males in the overproduction stage engaged in matched countersinging to the dialect played to them. These observations and the experiment support the selective attrition hypothesis: males visit and memorize a variety of dialects, probably in their hatching-year summer, overproduce dialects upon arrival the next spring, and then selectively retain the one dialect that matches the local song culture. Vocal plasticity late in life is not the result of a late sensitive phase for song memorization, but rather results from behavioural selection operating on a pre-existing repertoire of song dialects. Copyright 2000 The Association for the Study of Animal Behaviour.     

Population genetic structure and vocal dialects in an amazon parrot

The relationship between cultural and genetic evolution was examined in the yellow-naped amazon Amazona auropalliata. This species has previously been shown to have regional dialects defined by large shifts in the acoustic structure of its learned contact call. Mitochondrial DNA sequence variation from a 680 base pair segment of the first domain of the control region was assayed in 41 samples collected from two neighbouring dialects in Costa Rica. The relationship of genetic variation to vocal variation was examined using haplotype analysis, genetic distance analysis, a maximum-likelihood estimator of migration rates and phylogenetic reconstructions. All analyses indicated a high degree of gene flow and, thus, individual dispersal across dialect boundaries. Calls sampled from sound libraries suggested that temporally stable contact call dialects occur throughout the range of the yellow-naped amazon, while the presence of similar dialects in the sister species Amazona ochrocephala suggests that the propensity to form dialects is ancestral in this clade. These results indicate that genes and culture are not closely associated in the yellow-naped amazon. Rather, they suggest that regional diversity in vocalizations is maintained by selective pressures that promote social learning and allow individual repertoires to conform to local call types.     

Songbird: a unique animal model for studying the molecular basis of disorders of vocal development and communication

Like humans, songbirds are one of the few animal groups that learn vocalization. Vocal learning requires coordination of auditory input and vocal output using auditory feedback to guide one’s own vocalizations during a specific developmental stage known as the critical period. Songbirds are good animal models for understand the neural basis of vocal learning, a complex form of imitation, because they have many parallels to humans with regard to the features of vocal behavior and neural circuits dedicated to vocal learning. In this review, we will summarize the behavioral, neural, and genetic traits of birdsong. We will also discuss how studies of birdsong can help us understand how the development of neural circuits for vocal learning and production is driven by sensory input (auditory information) and motor output (vocalization).     

The social organization of resident-type killer whales (Orcinus orca) in Avacha Gulf,Northwest Pacific,as revealed through association patterns and acoustic similarity

Northeast Pacific resident-type killer whales (Orcinus orca) are known to form stable associations based on kinship between maternal relatives (matrilines) with a system of vocal dialects thought to reflect kinship relationships. We analyzed association patterns and acoustic similarity to study the social organization of killer whales in Avacha Gulf (Kamchatka, Russia), in the Northwest Pacific. The resident-type killer whales of Avacha Gulf formed temporally stable units that included maternal relatives with no dispersal observed. Acoustically, the killer whale community of Avacha Gulf was characterized by a system of dialects comparable to the communities of Northeast Pacific resident-type killer whales. Different units rarely associated with each other and these associations were nonrandom. Associations at different spatial levels did not always coincide with each other and with the patterns of acoustic similarity. Associations between units could change quickly irrespective of kinship relationships. The vocal dialect of a unit, which is more stable than the association patterns between units, might better reflect the overall kinship relationships. The stability and frequency of associations between units depended on the number of mature males in a unit, which could contribute to differences in the speed of change in vocal dialects and association patterns.     

The Response of Corn Buntings to Playback of Dialects

The response to playback of three different dialects by 10 territorial male corn buntings was investigated; the dialects played were own dialect, the dialect of a neighbouring population (NEAR) and a dialect from 40 km away (FAR). A significant effect of dialects was found for two measures of response, latency and singing rate. Response strength varies in the pattern OWN > NEAR > FAR for these measures. This pattern of response would not maintain the observed homogeneity of dialect populations. The results are similar to those obtained by experiments on other dialect species.     

Dialects of an invasive songbird are preserved in its invaded but not native source range

Biological invasions are not only events with substantial environmental and socioeconomic impacts but are also interesting natural experiments, allowing the study of phenomena such as the cultural evolution of bird song following introduction. We took an excellent opportunity to compare the distribution of dialects of the yellowhammer Emberiza citrinella, a small Eurasian passerine, in its native source region (Great Britain) and invaded range (New Zealand) more than hundred years after relocation. Recent field recordings (including those provided by volunteers within a citizen science project) were complemented by those from archives, each assigned to appropriate dialect by visual inspection of a sonogram, and the resulting spatial patterns of dialect distribution were interpreted using historical data on the yellowhammer invasion. The two countries differ markedly in the composition and distribution of dialects. New Zealand populations sing a greater number of different dialects, seven in total, five of which were not detected in the current British population, but have been reported by previous studies from the continental Europe. Two identified localities of capture (Brighton, Sussex, UK) and release (Dunedin, Otago, NZ) differ even more strikingly, having no dialects in common. The largely sedentary nature of yellowhammers allows for two mutually exclusive explanations for European dialects being detected in New Zealand but not in Great Britain: 1) the corresponding song types have emerged de novo in New Zealand, through convergent cultural evolution; 2) the dialects have disappeared from Great Britain, while being preserved in New Zealand. Indirect evidence from the widespread occurrence of these dialects in continental Europe and the reported stability of yellowhammer song, supports the latter explanation. We suggest that the yellowhammer dialect system is an avian equivalent of a phenomenon already noted in human languages, in which ancient words or structures are retained in expatriate communities.     

Born to sing! Song development in a singing primate

In animal vocal communication, the development of adult-like vocalization is fundamental to interact appropriately with conspecifics. However, the factors that guide ontogenetic changes in the acoustic features remain poorly understood. In contrast with a historical view of nonhuman primate vocal production as substantially innate, recent research suggests that inheritance and physiological modification can only explain some of the developmental changes in call structure during growth. A particular case of acoustic communication is the indris’ singing behavior, a peculiar case among Strepsirrhine primates. Thanks to a decade of intense data collection, this work provides the first long-term quantitative analysis on song development in a singing primate. To understand the ontogeny of such a complex vocal output, we investigated juvenile and sub-adult indris’ vocal behavior, and we found that young individuals started participating in the chorus years earlier than previously reported. Our results indicated that spectro-temporal song parameters underwent essential changes during growth. In particular, the age and sex of the emitter influenced the indris’ vocal activity. We found that frequency parameters showed consistent changes across the sexes, but the temporal features showed different developmental trajectories for males and females. Given the low level of morphological sexual dimorphism and the marked differences in vocal behavior, we hypothesize that factors like social influences and auditory feedback may affect songs’ features, resulting in high vocal flexibility in juvenile indris. This trait may be pivotal in a species that engages in choruses with rapid vocal turn-taking.     

Dialects in southern Rocky Mountain pikas, Ochotona princeps (Lagomorpha)

This work quantifies the geographic variation (dialects) in the vocalizations of southern Rocky Mountain pikas and presents data on the vocal responses of pikas to playback of recorded vocalizations of two dialects. Pika vocalizations were tape-recorded in twenty-six locations in Wyoming, Colorado, Utah and New Mexico. Two dialects (based on duration of note and frequency of fundamental) were found in short calls. One dialect was north of the Colorado River (dialect A), and the other was south of the Colorado River (dialect B). There was seasonal variation in the incidence of vocalizations with a peak of songs in late spring and a peak of short calls in late summer. Results of this study indicate that acoustic characteristics of vocalizations could be a useful taxonomic tool in the genus Ochotona.     

Threatened Corals Provide Underexplored Microbial Habitats

Contemporary in-depth sequencing of environmental samples has provided novel insights into microbial community structures, revealing that their diversity had been previously underestimated. Communities in marine environments are commonly composed of a few dominant taxa and a high number of taxonomically diverse, low-abundance organisms. However, studying the roles and genomic information of these “rare” organisms remains challenging, because little is known about their ecological niches and the environmental conditions to which they respond. Given the current threat to coral reef ecosystems, we investigated the potential of corals to provide highly specialized habitats for bacterial taxa including those that are rarely detected or absent in surrounding reef waters. The analysis of more than 350,000 small subunit ribosomal RNA (16S rRNA) sequence tags and almost 2,000 nearly full-length 16S rRNA gene sequences revealed that rare seawater biosphere members are highly abundant or even dominant in diverse Caribbean corals. Closely related corals (in the same genus/family) harbored similar bacterial communities. At higher taxonomic levels, however, the similarities of these communities did not correlate with the phylogenetic relationships among corals, opening novel questions about the evolutionary stability of coral-microbial associations. Large proportions of OTUs (28.7–49.1%) were unique to the coral species of origin. Analysis of the most dominant ribotypes suggests that many uncovered bacterial taxa exist in coral habitats and await future exploration. Our results indicate that coral species, and by extension other animal hosts, act as specialized habitats of otherwise rare microbes in marine ecosystems. Here, deep sequencing provided insights into coral microbiota at an unparalleled resolution and revealed that corals harbor many bacterial taxa previously not known. Given that two of the coral species investigated are listed as threatened under the U.S. Endangered Species Act, our results add an important microbial diversity-based perspective to the significance of conserving coral reefs.     

Birdsong: From behaviour to brain

Although vocal communication is wide-spread in animal kingdom, the use of learned (in contrast to innate) vocalization is very rare. We can find it only in few animal taxa: human, bats, whales and dolphins, elephants, parrots, hummingbirds, and songbirds. There are several parallels between human and songbird perception and production of vocal signals. Hence, many studies take interest in songbird singing for investigating the neural bases of learning and memory. Brain circuits controlling song learning and maintenance consist of two pathways — a vocal motor pathway responsible for production of learned vocalizations and anterior forebrain pathway responsible for learning and modifying the vocalizations. This review provides an overview of the song organization, its behavioural traits, and neural regulations. The recently expanding area of molecular mapping of the behaviour-driven gene expression in brain represents one of the modern approaches to the study the function of vocal and auditory areas for song learning and maintenance in birds.     

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.     

SONG INHERITANCE AND MATING IN A SONGBIRD WITH LOCAL DIALECTS

ABSTRACT

In this paper we document the pattern of geographic variation in song of the Corn Bunting in a marked population in Sussex. Song variation is best described as a system of local dialects with three song types in each dialect. We examine the inheritance of dialects from father to son; sons sing the same dialect as their nearest neighbour, rather than inheriting the dialect of the father. Therefore songs seem to be learned after dispersal. We also compare the dialects of mates and fathers of females: our results suggest that females do not rely on dialects when pairing. These results are discussed in the context of the current controversy surrounding other species with dialects and hypotheses relating dialects to the genetic structure of populations.