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Vocal mimicry in songbirds
Abstract
Baylis (1982, Acoustic Communication in Birds, Academic Press) decried the serious lack of experimental verification for the various hypotheses proposed to explain vocal mimicry in songbirds. With few exceptions, our understanding of the function and acquisition of this fascinating behaviour seems to have scarcely progressed. We examine the proposed functional explanations and supporting evidence, and summarize advances made since Baylis's (1982) review. We conclude that there is no compelling evidence to support any of the functional hypotheses but, rather, that almost all of the data concerning song mimicry are consistent with the learning mistakes hypothesis, whereby birds learn simple and common sounds, frequently using them in inappropriate contexts. Additionally, many apparently mimicked sounds are calls, not songs, which themselves may not be learned by the models. It is plausible that many examples of call mimicry are, in fact, due to evolutionary convergence.
... Vocal mimicry, where one species vocally copies the sounds of another, occurs among 15-20% of avian species [1]. While potential functions for this phenomenon have received extensive speculation, there is a lack of empirical data supporting proposed explanations [2,3]. Vocal mimicry has been described in both interspecific [4][5][6] and intraspecific contexts [7], suggesting multifaceted functions across species [3,8]. ...
... Vocal mimicry has been described in both interspecific [4][5][6] and intraspecific contexts [7], suggesting multifaceted functions across species [3,8]. Functional explanations for mimicry include threat avoidance, sexual selection, social affiliation, brood parasitism [2], and kleptoparasitism [6]. A mimetic signaling system is composed of the model (species being mimicked), mimic (species imitating the model), and audience (receiver of the signal) [9,10]. ...
... Another key consideration is that humans might be "predators." Human observers were present during all surveys in this study with no effort to conceal themselves from jays; though these suburban jays were habituated to humans, humans cannot be ruled out as the target of a mimicked signal [2]. Previous studies on this population of jays have documented individual variation in degrees of explorative and risk-taking behaviors [24,27,32,63]. ...
Avian vocal mimicry has been described in a variety of contexts, suggesting its function is multifaceted within and across species; however, basic empirical data describing mimetic signal prevalence and context are lacking for numerous species. We examined the occurrence and context of mimicked Red-shouldered Hawk (Buteo lineatus) calls over a 12-month period in a population of 49 individually color-marked Steller’s Jays (Cyanocitta stelleri). We documented mimicry of Red-shouldered Hawk calls in 14 of 49 (28.6%) jays during this 12-month period. We also reviewed the occurrence of the behavior in historic observation data. Hawk mimicry occurred more often during the early breeding season when jays were within home territories, their mates were present, and aggression was absent. Younger, larger, and bolder jays were most likely to perform imitations. These results suggest jays individually vary in mimetic propensity, and individuals’ proclivity for mimicry may be influenced by social and ecological contexts, physical characteristics, and personality traits.
... One hypothesis developed exclusively to explain avian vocal mimicry is that it functions to attract mates (Baylis, 1982;Dobkin, 1979;Kelley et al., 2008), but rarely has this hypothesis been tested formally (Dalziell et al., 2015;Kelley et al., 2008). The mate attraction hypothesis attempts to explain why the males of several species of oscine passerine, from disparate families, routinely incorporate imitations of multiple heterospecific sounds into their complex vocal displays (e.g. common starlings, Sturnus vulgaris, Hindmarsh, 1984; black-browed reed warblers, Acrocephalus bistrigiceps, Hamao & Eda-Fujiwara, 2004; northern mockingbirds, Mimus polyglottos, Gammon & Altizer, 2011;Albert's lyrebirds, Menura alberti, Putland et al., 2006). ...
... One hypothesis developed exclusively to explain avian vocal mimicry is that it functions to attract mates (Baylis, 1982;Dobkin, 1979;Kelley et al., 2008), but rarely has this hypothesis been tested formally (Dalziell et al., 2015;Kelley et al., 2008). The mate attraction hypothesis attempts to explain why the males of several species of oscine passerine, from disparate families, routinely incorporate imitations of multiple heterospecific sounds into their complex vocal displays (e.g. common starlings, Sturnus vulgaris, Hindmarsh, 1984; black-browed reed warblers, Acrocephalus bistrigiceps, Hamao & Eda-Fujiwara, 2004; northern mockingbirds, Mimus polyglottos, Gammon & Altizer, 2011;Albert's lyrebirds, Menura alberti, Putland et al., 2006). ...
... Dowsett-Lemaire, 1979;Howard, 1974). Observations such as these have led to the suggestion that vocal mimicry evolves as a by-product of selection for large repertoires (Baylis, 1982;Hindmarsh, 1986;Howard, 1974;Kelley et al., 2008), as larger vocal repertoires are commonly correlated with male mating success in many nonmimicking species (reviewed in Catchpole & Slater, 2008). In this by-product hypothesis, repertoires of mimetic vocalizations are either functionless mistakes or have the same function as repertories of species-specific song types (Dalziell et al., 2015). ...
Mimicry has long been a focus of research, but little is known about how and why many species of bird incorporate imitations of heterospecific sounds into their vocal displays. Crucial to understanding mimetic song is determining what sounds are mimicked and in what contexts such mimicry is produced. The superb lyrebird, Menura novaehollandiae, is a large oscine passerine with a lek-like mating system. Both sexes are accurate and versatile vocal mimics of the vocalizations of other species, but little is known about how males deploy their repertoire of mimicked sounds across contexts. Using extended focal watches, we recorded adult males displaying during the breeding season. We found that males mimicked heterospecific songs and nonalarm calls during ‘recital’ displays usually performed while they were perched and visually inconspicuous. In contrast, during visually conspicuous ‘dance’ displays, commonly performed on display mounds, males only mimicked heterospecific alarm calls. While much rarer than recital displays, dance displays were associated with the final stages of mate choice preceding copulation. These results provide the first evidence of any species varying its repertoire of mimicked sounds with different sexual contexts. Previous work suggests that mimicry in dance displays functions deceptively to manipulate the antipredator responses of females during the final stages of courtship. However, the structure and context of recital mimicry closely resembles the sexual advertisement song performed by nonmimicking songbirds. Given the importance of mimicry in the acoustic ecology of lyrebirds, our results suggest that with recital song males advertise the quality of their mimicry as it likely benefits both male and female offspring. Our finding that male superb lyrebirds mimic functionally distinct heterospecific vocalizations during different modes of courtship suggests that the evolution and maintenance of avian vocal displays are more complex than previously thought.
... It is estimated that 15-20% of songbirds worldwide could be considered as "vocal mimics" (Baylis 1982;Dalziell et al. 2015;Kelley et al. 2008), with vocal mimicry differing Figure 2. Song development and images of songbirds commonly studied with regard to late song (S2) learning. (A) As juvenile (<90 d of age) zebra finches mature, their songs become increasingly similar to those of their tutor. ...
... It is estimated that 15-20% of songbirds worldwide could be considered as "vocal mimics" (Baylis 1982;Dalziell et al. 2015;Kelley et al. 2008), with vocal mimicry differing from canonical song learning in that it is characterized by the imitation of sounds created by other species as well as anthropogenic sounds (Dalziell et al. 2015;Goller and Shizuka 2018). 5 For example, lyrebirds are virtuoso mimics that are able to reproduce construction noises, car sirens, and human voices; streaked bowerbirds have been observed to imitate dogs barking and trees being chopped and crashing to the ground; and magpies have been found to imitate human speech. ...
... However, the same cautions noted above about adult song learning should be applied to mimicry, along with an additional caveat. Acoustic similarities across species can arise in the absence of learning because many innate, unlearned vocalizations (e.g., various calls) are acoustically similar across species ("convergence"; Dalziell et al. 2015;Kelley et al. 2008). Consequently, while the acoustic properties and functionalities could be sufficiently similar to qualify vocalizations as mimicry, vocal similarities across species should not be related to L2 speech acquisition (or any other form of vocal learning) without demonstration of learning (i.e., the extent to which experiences lead to vocal similarities between mimics and heterospecifics). ...
Comparisons between the communication systems of humans and animals are instrumental in contextualizing speech and language into an evolutionary and biological framework and for illuminating mechanisms of human communication. As a complement to previous work that compares developmental vocal learning and use among humans and songbirds, in this article we highlight phenomena associated with vocal learning subsequent to the development of primary vocalizations (i.e., the primary language (L1) in humans and the primary song (S1) in songbirds). By framing avian “second-song” (S2) learning and use within the human second-language (L2) context, we lay the groundwork for a scientifically-rich dialogue between disciplines. We begin by summarizing basic birdsong research, focusing on how songs are learned and on constraints on learning. We then consider commonalities in vocal learning across humans and birds, in particular the timing and neural mechanisms of learning, variability of input, and variability of outcomes. For S2 and L2 learning outcomes, we address the respective roles of age, entrenchment, and social interactions. We proceed to orient current and future birdsong inquiry around foundational features of human bilingualism: L1 effects on the L2, L1 attrition, and L1<–>L2 switching. Throughout, we highlight characteristics that are shared across species as well as the need for caution in interpreting birdsong research. Thus, from multiple instructive perspectives, our interdisciplinary dialogue sheds light on biological and experiential principles of L2 acquisition that are informed by birdsong research, and leverages well-studied characteristics of bilingualism in order to clarify, contextualize, and further explore S2 learning and use in songbirds.
... Birds during the breeding season are subject to pressure from nest predation (Martin 1995;Lima 2009;Ibáñez-Álamo et al. 2015) and have evolved antipredator strategies (Caro 2005;Fontaine & Martin 2006;Lima 2009;Morosinotto et al. 2010;Zub et al. 2017 predators or take advantage of human settlements as shelters (Møller 2010;Roper et al. 2010;Liang et al. 2013). When encountering predators, many birds avoid being preyed on through active nest defense (Montgomerie & Weatherhead 1988;Krams et al. 2014;Burtka & Grindstaff 2015), or use sound signals to keep predators away (Kelley et al. 2008;Suzuki 2011;Hetrick & Sieving 2012;Gill & Bierema 2013;Krams et al. 2014;Zub et al. 2017). ...
... Sound mimicry has been reported in various animal species (Jourdain 1929;Chisholm 1932;Rails et al. 1985;Poole et al. 2005;Dalziell et al. 2015;Goller & Shizuka 2018;Riegert & Jůzlová 2018). There are many explanations for why birds exhibit sound mimicry (Robinson 1991;Payne et al. 1998;Chu 2001;Goodale & Kotagama 2006;Coleman et al. 2007;Kelley et al. 2008;Krams et al. 2014;York & Davies 2017;Zub et al. 2017;Jiang et al. 2021), and an important one is acoustic Batesian mimicry, that is, bird mimicking the sound of a poisonous or inedible dangerous species to scare off other predators (Sibley 1955;Rowe et al. 1986;Owings et al. 2002;Kelley et al. 2008;Krams et al. 2014;Zub et al. 2017;Møller et al. 2021a). For instance, incubation female tits of Paridae emitted the hissing call to make predators mistake for a snake (Sibley 1955;Perrins 1979;Rowe et al. 1986;Cramp & Perrins 1994;Broughton 2005Broughton , 2012Krams et al. 2014;Zub et al. 2017;Dutour et al. 2020;Møller et al. 2021aMøller et al. , 2021b. ...
... Sound mimicry has been reported in various animal species (Jourdain 1929;Chisholm 1932;Rails et al. 1985;Poole et al. 2005;Dalziell et al. 2015;Goller & Shizuka 2018;Riegert & Jůzlová 2018). There are many explanations for why birds exhibit sound mimicry (Robinson 1991;Payne et al. 1998;Chu 2001;Goodale & Kotagama 2006;Coleman et al. 2007;Kelley et al. 2008;Krams et al. 2014;York & Davies 2017;Zub et al. 2017;Jiang et al. 2021), and an important one is acoustic Batesian mimicry, that is, bird mimicking the sound of a poisonous or inedible dangerous species to scare off other predators (Sibley 1955;Rowe et al. 1986;Owings et al. 2002;Kelley et al. 2008;Krams et al. 2014;Zub et al. 2017;Møller et al. 2021a). For instance, incubation female tits of Paridae emitted the hissing call to make predators mistake for a snake (Sibley 1955;Perrins 1979;Rowe et al. 1986;Cramp & Perrins 1994;Broughton 2005Broughton , 2012Krams et al. 2014;Zub et al. 2017;Dutour et al. 2020;Møller et al. 2021aMøller et al. , 2021b. ...
Breeding tits in the family Paridae let out a hissing call when encountering nest predators, which is thought to be acoustic Batesian mimicry. The antipredator effect of the hissing call of Paridae has only been confirmed in several studies. To identify whether the hissing call of Japanese tits (Parus minor) affects the feeding behavior of the nest predator Swinhoe’s striped squirrel (Tamiops swinhoei), we played back white noise, the call of Oriental turtle doves (Streptopelia orientalis), and the hissing call of Japanese tits to squirrels. The squirrels responded differently to the three types of sounds played back. The proportion of squirrels that still fed while the hissing call of tits being played (26.1%) was significantly lower than that when white noise (91.3%) and the call of doves (85.7%) being played. The alert time of feeding squirrels to the hissing call of tits was also significantly longer than that to white noise and the call of doves. Our study suggests that the hissing call of tits can change the feeding behavior of the nest predator squirrel, which may reduce nest predation in cavity birds.
Please find the paper via link below:
https://www.tandfonline.com/eprint/CFMWKJ5QSQWAB3XAQAPF/full?target=10.1080/03949370.2021.1989053
... Vocal mimicry refers to the ability of copy sounds produced by other species (Kroodsma & Baylis 1982) and it has a widespread occurrence among birds, especially the oscine passerines (Baylis 1982). Although its function is still not well understood, Kelley et al. (2008) proposes two explanations for heterospecific vocal copying. It can help either avoiding competitors and predators (interspecific communication) or signaling to mates in a sexual context (intraspecific communication) (Kelley et al. 2008). ...
... Although its function is still not well understood, Kelley et al. (2008) proposes two explanations for heterospecific vocal copying. It can help either avoiding competitors and predators (interspecific communication) or signaling to mates in a sexual context (intraspecific communication) (Kelley et al. 2008). The study of vocal mimicry is important since it is related to social and ecological contexts (Hindmarsh 1984), and it evolved through natural and sexual selection to serve as mediator of several aspects of bird's life. ...
... Vocal mimicry could occur by learning or convergence (Kelley et al. 2008). In learning processes, individuals may include heterospecific vocal signals in a sensitive phase of its vocal development (Beecher & Brenowitz 2005). ...
Vocal mimicry is the ability of some bird species to copy heterospecific vocalizations in order to establish deceptive or non-deceptive interactions between an emitter and a receiver. This kind of vocal behavior is well documented in several species of New World Blackbirds (Icteridae family), but not in Scarlet-headed Blackbird ( Amblyramphus holosericeus ). Here we report the first event of vocal mimicry of this species, where a single individual imitated the vocal signals of Smooth-billed Ani ( Crotophaga ani ; Cuculiformes, Cuculidae). We argue that such behavior could have a deceptive role, increasing the predation avoidance and foraging efficiency of A. holosericeus by luring heterospecific individuals to form a mixed-flock.
... While vocal mimicry has arisen repeatedly within the songbird clade (60), the underlying evolutionary mechanisms remain unknown. Vocal mimicry tends to be exhibited by songbirds that are continuous singers with large repertoires instead of being limited to particular habitats, geographical regions, or mating systems (71,72). Recent genome sequencing studies have revealed that interspecific hybridization is more prevalent than previously speculated and can contribute to introgression and speciation. ...
... Recent genome sequencing studies have revealed that interspecific hybridization is more prevalent than previously speculated and can contribute to introgression and speciation. Our investigation found that F 1 hybrids between ZFs and CFs exhibited altered learning capacities, enabling them to acquire larger syllable repertoires and learn genetically unrelated heterospecific songs, which are foundational traits for vocal mimicry (60,72). Our findings suggest that interspecies hybridization could shape the modified learning capacity for species-specific learning constraints, allowing vocal mimicry during speciation in songbird species. ...
Learned behavior, a fundamental adaptive trait in fluctuating environments, is shaped by species-specific constraints. This phenomenon is evident in songbirds, which acquire their species-specific songs through vocal learning. To explore the neurogenetic mechanisms underlying species-specific song learning, we generated F 1 hybrid songbirds by crossing Taeniopygia guttata with Aidemosyne modesta . These F 1 hybrids demonstrate expanded learning capacities, adeptly mimicking songs from both parental species and other heterospecific songs more extensively than their parental counterparts. Despite the conserved size of brain regions and neuron numbers in the neural circuits for song learning and production, single-cell transcriptomics reveals distinctive transcriptional characteristics in the F 1 hybrids, especially in vocal-motor projection neurons. These neurons exhibit enrichment for nonadditively expressed genes, particularly those related to ion channel activity and cell adhesion, which are associated with the degree of song learning among F 1 individuals. Our findings provide insights into the emergence of altered learning capabilities through hybridization, linked to cell type–specific transcriptional changes.
... Despite their overall species-specific and -diagnostic nature, many bird calls and songs show strong resemblance to that of other species (Goller and Shizuka 2018). However, such resemblance does not always contain information which could be utilized by the receiver (Garamszegi et al. 2007;Kelly et al. 2008). In other cases, interspecific mimicry may have functions adapted to specific purposes; accordingly, Dalziell et al. (2015) defined interspecific vocal resemblance as vocal mimicry, when the receivers change their behaviour and it confers a selective advantage to the mimetic senders. ...
... For example, in mixed-species foraging flocks, senders may manipulate other species with mimetic sounds, e.g., with calls mimicking predators or the alarm calls used by heterospecifics toward predators (Chu 2001;Goodale and Kotagama 2006a;Flower et al. 2012;Goodale et al. 2014). Vocal mimicry may also function in avoiding nest predation and in various intraspecific contexts, including increasing sexually-selected song repertoires if females prefer such repertoires (Kelly et al. 2008), or deceiving the other sex (Dalziell et al. 2021). ...
Mimicry is a widespread phenomenon whereby predatory or parasitic individuals can access unsuspecting prey or hosts for the former’s benefit. For example, brood parasitic common cuckoos (Cuculus canorus) evolved several adaptations to trick hosts, including host-mimetic eggs, a barred chest plumage resembling the predatory Eurasian sparrowhawk (Accipiter nisus), and the female cuckoos’ bubbling calls considered as highly similar to this raptor’s calls. The sparrowhawk-like call mimicry is thought to threaten hosts while female cuckoos lay their eggs, although the similarity is restricted to the call’s fundamental frequency and not to its harmonics. However, these calls are also used in conspecific contexts, for example for mate attraction. If vocal mimicry is highly adapted toward the heterospecific function, it might cause reduced effectiveness in conspecific communication. We played cuckoo bubbling and sparrowhawk calls to territorial male cuckoos to test whether conspecific receivers process the mimetic calls accurately. All male cuckoos approached the speaker when female cuckoo calls were played, but rarely (7%) approached it when sparrowhawk or green woodpecker (Picus viridis; control) calls were played. When we excised the harmonic overtones from the sparrowhawk stimulus files, making these calls structurally more similar to the pure-tone female cuckoo calls, nearly half (43%) of the cuckoo males approached the speaker. Consequently, the difference in calls’ harmonic structure may explain one component of the inaccurate state of this acoustic mimicry. This imperfect mimicry by female cuckoos’ bubbling call to sparrowhawk call may ensure the multipurpose functions of this vocalization, including both intra- and interspecific contexts.
Significance statement
Common cuckoos are obligate brood parasites, laying their eggs into other species’ nests. During laying, female cuckoos utter sparrowhawk-like vocalizations (bubbling calls), to threaten hosts and to evade their defenses. However, they also use this same call to communicate with other female and male cuckoos. If the bubbling call mimics closely sparrowhawks’ calls, cuckoos may also recognize and respond to the sparrowhawk call, the call of a predator, as a cuckoo call. We used playback experiments to show that cuckoos distinguished between bubbling and sparrowhawk calls in nearly all cases. When we manipulated sparrowhawk calls to be more similar acoustically to bubbling calls by deleting overtones, recognition errors increased from 7 to 43%. We conclude that mimicry of sparrowhawk calls by female cuckoo calls is imperfect, which allows it to function in cuckoo-cuckoo communication effectively.
... Birdsong is thus a textbook example of a trait whose specific characteristics depend on the social environment, and nearly all hypotheses for the evolution of avian vocal learning are based on some form of social selection (Nowicki and Searcy 2014). However, while VPL per se is generally considered to produce optimal vocal behavior, there is much less agreement as to whether copying heterospecific vocalizations constitutes optimal vocal behavior (Kelley et al. 2008;Dalziell et al. 2015). Whether it does or not hinges primarily on the effect it has on interspecific aggressive interactions, as interspecific mating is assumed to affect fitness negatively (Mayr 1963). ...
... One view of mixed singing is that it is an example of where the gambit fails: a cognitive mechanism (vocal learning) yields a suboptimal behavior (mixed singing). Indeed, mixed singing is often described as a consequence of "misdirected learning" or a "learning mistake" (Kelley et al. 2008). Others have suggested that mixed singing allows individuals to better match their competitive social environment, thus implicitly supporting the validity of the behavioral gambit ). ...
Most animals exist in some type of social environment. The composition of this environment can impact diverse traits and behaviors, and is increasingly recognized as an important modulator of ecological and evolutionary processes. In this thesis, I examine the interplay between spatial and vocal behavior of male Wood Warblers and three different elements of the social environment: conspecific males, conspecific females, and closelyrelated heterospecifics. In Chapter 2, I investigate three hypotheses for conspecific attraction in male Wood Warblers (Phylloscopus sibilatrix): the habitat location cues hypothesis, the habitat quality cues hypothesis, and the female preference hypothesis. The habitat location cues hypothesis posits that the presence of conspecifics provides social information that indicates the location of potentially suitable habitat, and is thus useful during the search phase of habitat selection. The habitat quality cues hypothesis suggests that conspecific presence provides social information that the local habitat is suitable, and is thus useful during the assessment phase of habitat selection. The female preference hypothesis proposes that males are attracted to settle near conspecifics because females prefer to mate with males in aggregations. My colleagues and I used a combination of a two-year playback experiment, spatial point process models and mate choice models to test the above hypotheses. The results showed that spatial variation in habitat quality was a better predictor of male settlement patterns than proximity to simulated conspecifics, and that aggregated males were not more successful in attracting females. Taken together, the results are most consistent with the habitat location cues hypothesis. In Chapter 3, I explore the relationship between the within-season movements of male birds and mate searching. I suggest that mate searching may be a conceptual framework that can unify temporary movements associated with polyterritoriality and extra-territorial forays as well as permanent movements associated with breeding dispersal. I test four predictions derived from this framework by analyzing the relationship between emigration decisions of male Wood Warblers, ecological conditions in the current territory and mating potential in the current territory. Male choices to emigrate were strongly related to cues that mating potential in the current territory was low, as predicted by the mate searching hypothesis. In Chapter 4, I examine how mixed singing in Wood Warblers affects their ability to co-occur with their locally more abundant sister species, the Western Bonelli’s Warbler (“Bonelli’s Warbler,” P. bonelli). It has been hypothesized that an increase in interspecific acoustic similarity (e.g., via mixed singing) might facilitate co-occurrence via either an increase in competitor recognition (promoting interspecific territoriality) or reduced aggression (due to enhanced neighbor recognition). Alternatively, it has also been suggested that interspecific asymmetries in aggression (which could result from an asymmetry in acoustic similarity) cause competitive exclusion of the less aggressive species. To determine which if any of these scenarios might be occurring between Wood and Bonelli’s Warblers, I conducted a song playback experiment, calculated levels of interspecific territory overlap and determined patterns of co-occurrence at the study site level. The results were not consistent with any of the hypotheses tested, suggesting that mixed singing in Wood Warblers neither helps nor hinders co-occurrence with Bonelli’s Warblers. By considering the multi-faceted nature of the social environment, this thesis brings together diverse topics for a more comprehensive understanding of social influences on the breeding behavior of migratory songbirds. The social environment of most species has and continues to be altered by human-induced global change. Thus, it remains an ongoing and important task to try to understand the behavioral, ecological and evolutionary consequences of these changes.
... Sound mimicry is a relatively frequent behaviour in birds (Hindmarsh 1986, Kelley et al. 2008). There are many evolutionary hypotheses regarding the possible function of mimicry including the deception of other birds, avoiding heterospecific competition, individual identification, or mate attraction. ...
... However, most of these theories currently have little backing or have been definitively rejected. It is likely that this behaviour is related simply to mistakes during song-learning processes (Hindmarsh 1984(Hindmarsh , 1986Kelley et al. 2008). ...
... Similarly, when burrowing owls (Athene cunicularia) are scared, they produce hisses that resemble a rattlesnake's rattle (Rowe et al. 1986). A key review of this topic argued that most reported cases of vocal mimicry lacked solid experimental evidence, and that vocal mimicry requires a specific learning process to adopt model features (Kelley et al. 2008). This restrictive definition, however, favors one particular mechanism underlying the origin of mimicry while disregarding evolutionary convergence (Dalziell and Welbergen 2016). ...
... It is debatable whether vocal mimicry requires learning in order to evolve (Kelley et al. 2008;Dalziell et al. 2015). Vocal learning is not a likely mechanism for the evolution of hisses in birds since birds would be required to be exposed to this sound and subsequently learn it. ...
Hole-nesting tits belonging to the family Paridae produce a hissing display that resembles the exhalatory hiss of a snake. When a predatory animal enters the nest hole of a tit, tits often hiss vigorously, while lunging their head forward and shaking their wings and tail, until the intruder retreats. We assessed the acoustic similarity between such hiss calls from six species of tits, snake hisses and tit syllables used in alarm vocalizations, as well as white noise as a control. Tit hiss calls showed a high degree of similarity with snake hisses from three different snake families. Tit hisses had lower similarity to syllable alarm calls, suggesting convergence of tit hisses in their spectral structure. Hiss calls would only be effective in protecting nest boxes if nest predators responded to these calls. In order to test this hypothesis, we trained individual Swinhoe’s striped squirrels Tamiops swinhoei hainanus, a common predator of egg and nestling tits, to feed at feeders in proximity to nest boxes. We compared the aversive response of squirrels to tit’s hiss calls and white noise, presented in random order. Squirrels showed a higher degree of avoidance of feeders when hiss calls were played back than when white noise was presented. In conclusion, our study suggests that hole-nesting birds have evolved convergent snake-like hiss calls, and that predators avoid to prey on the contents of nest boxes from which snake-like hisses emerge.
... Vocal mimicry has also been studied (Dalziell et al. 2015;Dalziell and Welbergen 2016), although to a much lesser degree. In birds, different functional explanations for vocal mimicry have been suggested, which fall into two categories: intraspecific communication (sexual context or social affiliation) and interspecific communication (avoidance of threats or competitors) (Kelley et al. 2008). In the second case, vocal mimicry is known to occur during predator-prey interactions (Dalziell et al. 2015), and such heterospecific mimicry can take on two main functional forms. ...
... For instance, it has been suggested that Neomorphus ground cuckoos mimic peccary tooth clacking to deter predators such as mustelids or small felids (Amaral et al. 2017). Because of the clear selective advantage to mimic other species to deter competitors and predators (Kelley et al. 2008), ones may question to what extent this behavior is frequent in nature. ...
After publication of this paper, the authors determined an error in the article title.
... Vocal mimicry has also been studied (Dalziell et al. 2015;Dalziell and Welbergen 2016), although to a much lesser degree. In birds, different functional explanations for vocal mimicry have been suggested, which fall into two categories: intraspecific communication (sexual context or social affiliation) and interspecific communication (avoidance of threats or competitors) (Kelley et al. 2008). In the second case, vocal mimicry is known to occur during predator-prey interactions (Dalziell et al. 2015), and such heterospecific mimicry can take on two main functional forms. ...
... For instance, it has been suggested that Neomorphus ground cuckoos mimic peccary tooth clacking to deter predators such as mustelids or small felids (Amaral et al. 2017). Because of the clear selective advantage to mimic other species to deter competitors and predators (Kelley et al. 2008), ones may question to what extent this behavior is frequent in nature. ...
Batesian mimicry refers to a harmless species protecting itself from predators by mimicking a harmful species. A case of acoustic Batesian mimicry has been proposed in the naturalist literature: it is suspected that birds called like a snake when disturbed in their cavities to deter mammalian predators or repel competitors. To evaluate this hypothesis, we first test the assumption that the hissing sound produced by adult females of a wild cavity-nesting species – the blue tit (Cyanistes caeruleus) – is acoustically similar to the hisses of three wild sympatric snake species. Then, we tested one prediction of this hypothesis which is that the receiver of the signal should react similarly to the snake and bird hisses. To do so, we used, hiss-naïve individuals, without any past experience with predators: the house mouse (Mus musculus domesticus), representing a model of a possible nest competitor. We quantified mouse responses to blue tit and snake hisses and two non-hiss sounds (other blue tit vocalizations and human voices). Our results show that snake hisses and blue tit hisses are structurally more similar to each other than to other blue tit vocalizations and that both hisses provoke comparable levels of anxiety behavior in mice. Taken together, these results are compatible with the hypothesis that blue tits have evolved to mimic the sound of snakes, i.e., the Batesian mimicry hypothesis. We also note however that our results also agree with another hypothesis, suggesting that mechanisms underlying the production and perception of hisses are conserved across vertebrates. Further research is needed to disentangle these two hypotheses.
Significance statement
Mimicry is a fascinating illustration of the principles of evolution in communication. In the case of Batesian mimicry, species evolve to resemble other species as a mean of deterring harmful receivers. While visual mimicry has been thoroughly investigated across a wide range of species, vocal mimicry remains less studied. In the present study, we compared the acoustic similarity of the hissing sound produced by female blue tits, a cavity-nesting species, to the hisses of three snake species. Then, we exposed mice, a model of a possible cavity competitor, to bird and snake hisses. We showed that snake and blue tit hisses are acoustically similar and provoke comparable anxiety behaviors in mice. These results are compatible with the hypothesis that blue tits utilize an innate fear response to hisses in mammals, a result that may explain why blue tit hisses have been linked to increased survival by other authors. Furthermore, the results also suggest a conserved function of, and response to, hiss vocalizations across vertebrates.
... Imitating sounds from different species or anthropogenic sources, or allospecific vocal imitation, allows birds to add more vocal complexity to their vocal repertoire (13). This enhanced vocal variation can function to deter predators by reproducing allospecific alarm calls when disturbed at the nest, as in spotted bowerbirds (Ptilonorhynchus maculatus) (14), to imitate the vocalizations of host species during brood parasitism (cuckoos) (15) and to create complex songs to attract mates as a form of sexual selection in European starlings (Sturnus vulgaris) (16). ...
Vocal production learning is a widespread and remarkable phenomenon. However, the underlying mechanisms of allospecific vocal imitation are poorly understood. Parrots and corvids are well known for their imitation abilities, but imitation accuracy has not yet been studied across species in a comparative context. We compared imitation accuracy between nine parrot species and
European starlings based on imitation of monophonic and multiphonic sounds, produced by the Star Wars droid R2-D2. Our results show that starlings were better at imitating multiphonic sounds than parrots. However, no difference in imitation accuracy was found between parrots and starlings
when imitating monophonic sounds. The differences in imitating accuracy are likely based on a physiological difference in syrinx anatomy, rather than on perceptual or cognitive differences between starlings and parrots. Between our nine tested parrot species, we found that parrots with larger brains (e.g., African greys and amazon parrots) were less accurate at imitating monophonic
sounds than smaller brained budgerigars and cockatiels. The use of citizen science in our study shows the great potential this has to expand data collection beyond traditional studies. These findings contribute to a deeper understanding of the evolution of communication complexity in vocal learners.
... Group members of all ages and sex interact frequently in a diverse range of contexts [48], such as provisioning young [49,50], antipredator behaviour [51,52] and social bonding through play [53,54]. Vocally, magpies display high communicative flexibility, including a lifelong capacity for learning mimicry [55]. Their vocal system encompasses a range of vocalization types, including a discrete and combinatorial repertoire [21,56] and evidence for urgency coding in alarm calling [52,57]. ...
It has recently become clear that some language-specific traits previously thought to be unique to humans (such as the capacity to combine sounds) are widespread in the animal kingdom. Despite the increase in studies documenting the presence of call combinations in non-human animals, factors promoting this vocal trait are unclear. One leading hypothesis proposes that communicative complexity co-evolved with social complexity owing to the need to transmit a diversity of information to a wider range of social partners. The Western Australian magpie (Gymnorhina tibicen dorsalis) provides a unique model to investigate this proposed link because it is a group-living, vocal learning species that is capable of multi-level combinatoriality (independently produced calls contain vocal segments and comprise combinations). Here, we compare variations in the production of call combinations across magpie groups ranging in size from 2 to 11 birds. We found that callers in larger groups give call combinations: (i) in greater diversity and (ii) more frequently than callers in smaller groups. Significantly, these observations support the hypothesis that combinatorial complexity may be related to social complexity in an open-ended vocal learner, providing an important step in understanding the role that sociality may have played in the development of vocal combinatorial complexity.
This article is part of the theme issue ‘The power of sound: unravelling how acoustic communication shapes group dynamics’.
... Males often produce elaborate and complex vocalizations, such as songs or calls, to advertise their fitness, quality, and availability to potential mates. These signals may convey information about the male's genetic quality, health, territory ownership, or resources, helping to attract females and engage in successful reproductive encounters (Fröhlich et al. 2019;Blumstein et al. 2012;Kelley et al. 2008). ...
... For instance, in passerine birds, song complexity (repertoire size) depends not only on genetic factors, but also on the social and ontogenetic context (Nordby et al. 1999). In fact, a high density of conspecifics ), a high species richness (Kelley et al. 2008, Grant & Grant 2010) and a great abundance of resources during development (MacDonald et al. 2006) may promote the diversity of individual repertoires. Some studies have identified bird song complexity to be an honest signal of individual quality, with individual variation in song traits advertising male condition (Rowe & Houle 1996, Buchanan & Catchpole 1997. ...
Understanding the influence of intrinsic (genetic and morphological) and extrinsic (geographical, environmental and social) factors on the performance and spatial differentiation of sexual signals, such as bird song, can help identify behavioural indicators of individual quality, habitat degradation and social environment. We used the Iberian Bluethroat Luscinia svecica azuricollis , a migratory bird that breeds in fragmented landscapes dominated by shrublands, as a case study to: (1) assess how a set of acoustic indicators of song performance are driven by intrinsic and extrinsic factors; and (2) contrast deterministic (adaptations to the environmental context and morphological constraints) vs. stochastic (differentiation by geographical isolation) explanations for song differentiation patterns. We explored acoustic indicators of song performance (spectral, temporal and song complexity) in relation to parameters related to genetic structure, body size, habitat type, habitat quality (assessed through a spatially explicit modelling approach) and social context (population abundance and songbird community composition). Then, we explored the contribution of genetic, geographical and environmental dissimilarity to song diversification across space. Our results highlight an association of song spectral variables with genetic structure and a significant connection between song complexity and duration with habitat quality. We found no relationship between social features and acoustic variables, or between song differentiation and genetic or geographical distances. There was, however, a correlation between song differentiation and environmental dissimilarity. We recommend the consideration of song complexity as an indicator of habitat quality.
... In southern Africa, juvenile bushveld lizards (Heliobolus lugubris) reduce the risk of predation by mimicking a sympatric venomous beetle, the two-spotted ground beetle (Anthia thoracica) (Huey & Pianka 1977). However, unlike visual mimicry, which has been extensively studied, acoustic mimicry has received much less attention (Payne et al. 1998;Barber & Conner 2007;Kelley et al. 2008;Aubret & Mangin 2014;Flower et al. 2014;Brejcha 2019;Gammon & Corsiglia 2019;Vaughan et al. 2019;Allf et al. 2021;Ancillotto et al. 2022). ...
Mimicry is widespread in the animal kingdom, with sound/or acoustic mimicry remaining less studied than visual mimicry. Some incubating female birds in cavity nests emit a hissing call when encountering nest predators, which sounds like a snake hiss and serves to scare off predators; this is considered a form of acoustic
Batesian mimicry. Similarly, for nearly defenseless bird nestlings, using a hissing call to scare off predators can improve their survival; however, few studies have reported nestlings making hissing calls. In this study, we report on the hissing calls
of nestlings of the open-nesting zitting cisticola (Cisticola juncidis) and compare their hissing calls with those of other animals, such as birds and snakes. The results showed that the hissing calls of C. juncidis nestlings closely approximate the sounds of snakes. This study is the first report of sounds that mimic snakes made by the nestlings of any open-nesting passerine bird species.
... It is a well-known phenomenon in many organisms (Edmunds and Golding 1999). Even though mimicry is often imprecise, it exemplifies the mechanism of natural selection (Edmunds and Golding 1999) and is a quite frequently observed evolutionary strategy in the animal kingdom (Kelley et al. 2008;Moore and Hassall 2016). It allows either to protect an organism against potential predation (Maran 2017) or in the case of predators, to pretend to be another non-threatening organism. ...
Adaptive mimicry in animals is a well-known phenomenon. Here, we propose that a similarly adaptive strategy in humans is using kin terms for people who are not closely genetically related. Irrespective of the initiator attributing a kin term to a non-kin, we call this kin term mimicry (KTM). The emergence of human sociality and language allowed not only easy kin recognition, but also led to strong positive emotions related to such kin names as “mother,” “father,” “brother,” “sister,” “aunt” or “uncle.” Although the phenomenon of using kin terms of genetically unrelated people is well known in the social sciences, here we discuss it in the light of evolution. We notice this is an evolutionary adaptive cooperation strategy, which allows us to predict in which ecological or social circumstances it will be more prevalent. We postulate specific testable factors that affect the prevalence of kin mimicry. We also discuss who is more likely to be an initiator of calling non-kin a fictive kin, and who benefits from such behavior. The KTM hypothesis postulates that an individual or social group initiating or bestowing kin terms usually receives more benefits (economic and/or psychological support) from such mimicry.
... There is now good evidence that the recital mimicry of Albert's lyrebirds is a cultural construct (Backhouse et al., 2022), in contrast to some traditional views of avian vocal mimicry as simply a passive sampling of the environment (Hindmarsh, 1984;Kelley et al., 2008). Specifically, there is evidence that individual Albert's lyrebirds are influenced by other lyrebirds in both what to mimic (this study) and how to organize their mimicry (Backhouse et al., 2022). ...
Aim
Conservation has recently shifted to include behavioural or cultural diversity, adding substantial value to conservation efforts. Habitat loss and fragmentation can deplete diversity in learnt behaviours such as bird song by reducing the availability of song tutors, yet these impacts are poorly understood. Vocal mimicry may be particularly sensitive to habitat loss and fragmentation through the resulting reduction in both heterospecific models and conspecific tutors. Here we examine the relationship between habitat availability and both mimetic repertoire size and song composition in male Albert's lyrebirds (Menura alberti), a near‐threatened species renowned for its remarkable mimetic abilities.
Location
Eastern Australia.
Methods
We calculated repertoire size and composition from recordings of male Albert's lyrebirds from throughout the species' range. We estimated patch size and local habitat availability using a species distribution model and remotely sensed vegetation types. We assessed the local model species assemblage through species distribution models and automated acoustic detectors.
Results
Individual males in smaller habitat patches, or in areas with a lower proportion of suitable habitat, mimicked fewer model species and fewer vocalization types. However, they mimicked comparatively more vocalizations from each model species than individuals in larger patches or with more intact habitats. All model species were likely to occur in most study sites, suggesting that repertoires are not driven by the availability of model species.
Main Conclusions
Our results suggest that mimetic repertoire sizes are influenced by habitat availability through the number of lyrebird tutors. Further, individuals in disturbed habitats may partially compensate for mimicking fewer species by mimicking more vocalizations from each species. This study supports the hypothesis that cultural diversity may be impoverished by habitat loss and fragmentation in a similar way to genetic diversity. Variation in song diversity may therefore indicate population health and highlight populations in particular need of conservation action.
... A distinction sometimes made between vocal learning (the ability to learn sounds from conspecifics) and vocal mimicry (the ability to also learn sounds from heterospecifics or the environment; Kelley et al., 2008) could point to the relevance of timbre in other species. Just like possessors of absolute pitch identify the key of a piece more quickly if it is played on their primary instrument (Marvin & Brinkman, 2000), many animals may have difficulty parsing constituent frequencies of complex sounds with which they are not familiar. ...
... Although mimicry is usually related to appearance similarity, other forms of sensory mimicry also exist (Maran 2017;Font 2019). Sound mimicry, for instance, can be used to manipulate the behavior of other species (Kelley et al. 2008). Phainopeplas (Phainopepla nitens) mimic the sounds of some predatory birds to startle or distract the attacker (Chu 2001); thick-billed euphonias (Euphonia laniirostris) mimic yellow-green vireos (Vireo avoviridis) to send out alarm calls (Morton 1976); and fork-tailed drongos (Dicrurus adsimilis) issue false mock alerts to steal food from other animals (Flower 2011). ...
Imperfect Batesian mimicry is common in nature. Female common cuckoos (Cuculus canorus), for instance, seem to be imperfect mimics of hawks (Accipiter spp.) in both appearance and call. However, only few experiments have confirmed that female cuckoos can effectively mimic sparrowhawk calls. To test the effectiveness of female common cuckoos mimicking the call of hawks, we performed a playback experiment on two host bird species, namely the Oriental magpie-robin (Copsychus saularis) and white wagtail (Motacilla alba), and two potential host bird species, the crested myna (Acridotheres cristatellus) and Eurasian hoopoe (Upupa epops), during the non-breeding season in Hainan island, China. We found that while there are significant differences in the likelihood that different species respond to playback call types, they do not differ in how
they respond to the different calls, and that overall, the birds are more likely to respond to female cuckoo and hawk calls than to dove or male cuckoo calls, and with no significant difference between hawk and female cuckoo. Our results show that although female common cuckoos mimic the call of sparrowhawks imperfectly, they can mislead birds into displaying anti-predatory behavior. This study provides further evidence to support the recently proposed hypothesis that hawk mimicry in female cuckoo calls can not only fool their hosts, but also the non-host species.
... A mimic needs to resemble a heterospecific model closely enough to be mistaken by potential receivers as the model. These relations are often difficult to completely However, there has been little consensus on the function of such vocal mimicry, likely because of an overly strong conditional focus on vocal learning [2][3][4][5][6][7] . Consequently, the investigative framework of bird vocal mimicry differed from other fields and thus perhaps caused some oversight of its adaptive function(s) 2,5 . ...
During courtship, male lyrebirds create acoustic illusions of a flock of birds fending off a predator. These realistic illusions fool the imitated species to engage in mobbing, but intriguingly lyrebirds produce them only preceding or during copulation.
... Existem também características inatas que apresentam grande flexibilidade, como o canto dos pássaros. De acordo com Kelley et al. (2008), o estorninho (Sturnus vulgaris) pode mimetizar o canto de inúmeras aves, possuindo uma vocalização sonora com características flexíveis. Este mecanismo o permite transmitir os cantos miméticos para várias gerações, mas as mesmas vocalizações não são necessariamente encontradas em toda a espécie. ...
Um aspecto inerente à vida social está no fato dela ser regida em suas diferentes esferas por regras de convivência. Contudo, não é qualquer forma de interação social que pode ser colocada dentro do escopo da moralidade. O ponto central deste trabalho é encontrar um princípio de distinção entre as exigências que regem o comportamento moral daquelas presentes em outras formas de interação social. Indicarei no presente texto a possibilidade de uma abordagem evolucionista para esta questão. Defenderei que exigências morais possuem uma base emotiva e em que sentido este comportamento pode ser considerado inato. Em outras palavras, argumentarei em favor de que juízos morais são respostas emocionais circunscritas por emoções socialmente relevantes com base em mecanismos psicobiológicos de sociabilidade existentes devido à relação entre o ambiente e a estrutura natural de mamíferos sociais.
Palavras-chave: Moralidade. Naturalismo. Evolucionismo. Inatismo. Emoções.
... Other species are "open-ended learners"; canaries add some new material to their songs each breeding season, so that a bird's song changes from year to year (Nottebohm and Nottebohm, 1978). Still other species, such as mockingbirds (Mimus polyglottus), are mimics, and can reproduce sounds they hear almost immediately (Kelley et al., 2008). Critical period learners preferentially memorize songs with species-specific acoustic characteristics during an early critical phase of development, demonstrating that birds have genetically determined species-specific sensory predispositions (Marler and Peters, 1988). ...
Young songbirds draw the source material for their learned songs from parents, peers, and unrelated adults, as well as from innovation. These learned songs are used for intraspecific communication, and have well-documented roles for such functions as territory maintenance and mate attraction. The songs of wild populations differ, forming local “dialects” that may shift over time, suggesting that cultural evolution is at work. Recent work has focused on the mechanisms responsible for the cultural evolution of bird songs within a population, including drift, learning biases (such as conformity and rare-form copying), and selection (including sexual selection). In many songs or song repertoires, variability is partitioned, with some songs or song segments being stable and consistent, while others vary within the population and across time, and still others undergo population-wide transitions over time. This review explores the different mechanisms that shape the cultural evolution of songs in wild populations, with specific reference to a long-term investigation of a single population of philopatric Savannah sparrows. Males learn a single four-segment song during their 1st year and sing the same song thereafter. Within this song, the buzz segment is a population marker, and may be stable for decades – variant forms occur but eventually disappear. In contrast, the middle segment is highly variable both within the population and over time; changes in relative prevalence of different forms may be due to cultural drift or a rare-form learning bias. Within the introductory segment, a high note cluster was replaced by a click train between 1982 and 2010, following an S-shaped trajectory characteristic of both selective sweeps in population genetics and the replacement of one form by another in human language. In the case of the Savannah sparrows, this replacement may have been due to sexual selection. In subsequent generations, the number of clicks within trains increased, a form of cultural directional selection. In contrast to the narrowing of a trait's range during directional selection in genetic systems, variation in the number of clicks in a train increased as the mean value shifted because improvisation during song learning allowed the range of the trait to expand. Thus, in the single short song of the Savannah sparrow, at least four different mechanisms appear to contribute to three different types of cultural evolutionary outcomes. In the future, it will be import to explore the conditions that favor the application of specific (and perhaps conditional) learning rules, and studies such as the ongoing song seeding experiment in the Kent Island Savannah sparrow population will help in understanding the mechanisms that promote or repress changes in a population's song.
... Although this species occurs in a nearby forest block about 10 km away, the Serra das Cabras (22°54'02''S; 46°49'08''W), where I sound recorded individuals for comparison, the fact that I found only one individual with White-browed Warbler morphology in Serra dos Cocais suggests that its more direct competitors for territorial resources might be the locally abundant Flavescent Warbler. The absence of conspecifics might in turn favor interspecific vocal mimicry (Kelley et al. 2008). Notably, White-browed Warblers often sing in duets (Batistela and Müller 2019), a behavior believed to favor cooperative territorial defense by pairs. ...
Most birds, including songbirds, produce distinct, species-specific songs and calls. Here, I report on an individual bird of the Neotropical warbler genus Myiothlypis that produced vocalizations typical of two congeneric species. The “bilingual” bird, observed in the Serra dos Cocais region of São Paulo state, Brazil, appeared visually to be a White-browed Warbler (Myiothlypis leucoblephara) but was documented emitting songs and calls of that species and of Flavescent Warbler (Myiothlypis flaveola). Two possible explanations, not mutually exclusive, are raised and discussed, i.e., (i) hybridization between the two species, previously undocumented, and (ii) vocal imitation of both species assimilated into its vocal repertoire.
... Vocal mimicry can include con-specifics, other species or even man-made sounds. Many hypotheses have been made on the functions of vocal mimicry including suggestions that they may be involved in sexual selection by acting as an indicator of fitness, help brood parasites, or protect against predation, but strong support is lacking for any function (Kelley et al 2008). Many birds, especially those that nest in cavities, are known to produce a snakelike hissing sound that may help deter predators at close range (Marler & Hans 2004). ...
Avian vocalizations can have intra-specific and inter-specific functions such as communication alarm, resource location, pair-bond maintenance, territory defense, and mate attraction. Majority of studies have focused on the diurnal vocalization of birds. Very little research has been done on nocturnal vocalization behavior of birds such as francolins in Cameroon. For this reason, this study was aimed at assessing the importance of francolin vocalization in local time indication to the inhabitants of Mamfe municipality. The data collection method of this study comprised of random spot sampling of the francolin number, recording vocalizations in the dawn and dusk, and visiting the francolin nesting sites. Surveys were conducted 5 days per week, from Monday to Friday for a period of one month. In the dawn, call recording started 7:00am and ended 5:00pm, while in the dusk it started 7:00 pm and ended 6:00am. This study revealed a significant association between francolin number and the day-period, χ 2 = 19.219 df=6 P=0.004. Vocalization time and frequency showed a significant link, χ 2 = 6.834 df=8 P<0.05. Similar results were obtained from the association of bird number and vocalization frequency, χ 2 = 21.294 df=4 P=0.000. The bird number was proportionate to call frequency and intensity, 5 birds and above generated a call frequency of 64.79%. The day-period and bird number associated significantly, χ 2 = 51.278 df=44 P<0.05. Additionally, cropland vegetation showed a significant correlation on bird number, r = 0.244 P<0.05. Furthermore, the bird group-size witnessed an influence on the call location, with more calls from cropland (70.42%) than the forest vegetation (29.58%). The consistent vocalization frequency during the early hours of the morning period is useful to the local inhabitants of the municipality. Almost all the local crop-farmers interviewed acknowledged that the francolin vocalization were time-specific, hence, reminding them upon the preparation of early morning farming engagements. Moreover, it is believed in most part of Cameroon, especially in remote communities that the francolin vocalizations help to wake up local farmers from sleep during the early of the day. However, the declining population of this bird species raises many questions on its conservation.
... Birds often transmit information through sounds, but their calls consume more energy than visual and chemical signals; therefore, they use calls to transmit a large amount of information quickly and efficiently only when it is absolutely needed (Catchpole & Slater 2003). Batesian vocal mimicry is common in birds; birds can mimic the sounds of a poisonous, inedible, and dangerous species, thus gaining safety benefits (Sibley 1955;Kelly et al. 2008;Krams et al. 2014;Zub et al. 2017). Some birds will send out predator-like calls to scare off other predators when they are in danger. ...
Mimicry is widespread in the animal kingdom. Parasitic cuckoos can reduce the risk of their offspring being rejected by employing morphological and egg mimicry. Female common cuckoos (Cuculus canorus) can deceive their hosts by mimicking sparrowhawk (Accipiter nisus) calls, thus improving brood parasitism success. However, few experiments have confirmed the hypothesis that female cuckoos can successfully mimic sparrowhawk calls. We used two populations of wild free-range chickens (Gallus gallus domesticus), which are not cuckoo hosts, to study the effects of four different types of bird calls on their anti-predatory behavior. Results showed that both female cuckoo and sparrowhawk calls elicited vigilance and escape responses from chickens, while the chickens did not respond to either male common cuckoo or Oriental turtle dove (Streptopelia orientalis) calls. This suggests that female cuckoo calls can not only deceive their hosts, but also successfully deceive their non-host birds. Our study further confirms the accuracy with which female cuckoos can mimic sparrowhawk calls.
... About 15-20% of songbird species mimic the vocalizations of other species, commonly including their alarm calls (Marshall 1950;Baylis 1982;Kelley et al. 2008;Dalziell et al. 2015). Several species from at least 15 passerine families mimic heterospecific alarm calls (Table 12.1), and they can be given alone or in combination with nonmimetic vocalizations (Goodale and Kotagama 2006;Flower 2011;Wheatcroft and Price 2013;Igic and Magrath 2014;Dalziell and Welbergen 2016). ...
Many birds and mammals give alarm calls when they detect predators or other threats, and these calls have been used as classic models for understanding signal design. Here we consider signal design and usage, and how individuals acquire and use information from the alarm calls of other species. Alarm calls often encode detailed information on danger, such as the type of predator, its current behavior, size, or proximity. Alarm calls are sometimes very similar among species or can share generic acoustic features, and both help to explain recognition of heterospecific alarms. However, alarm calls can vary greatly among species, and taxonomically widespread eavesdropping also requires learning the association between calls and danger. Once heterospecifics eavesdrop on alarm calls, there is potentially selection on callers to modify their alarm calls or usage. If callers benefit from eavesdroppers’ responses to their alarm calls, they may be selected to enhance signal efficacy, leading to interspecific communication and mutual benefit. Alternatively, callers can be selected to manipulate eavesdroppers, using deceptive signaling, including mimicry, causing the eavesdropper to suffer a cost. If callers suffer a cost from eavesdroppers’ responses, their signaling can be modified to make eavesdropping harder, leading to cue denial. Overall, alarm signals provide an insight into the evolution of signal design, and the complex flow of information within and among species in natural communities.
... Thus, instead of being an 'aggressive' signal, i.e. purely an expression of emotion, it is possible that the broadband trill contains information that warns of a potential hazard, i.e. the signaller will pose a threat if provoked. Moreover, phenomena such as mimicry (Kelley et al. 2008;Schachner et al. 2009) shown by the European starling (West et al. 1983), the mynah bird (Archawaranon 2005), and some species of parrot (Cruickshank et al. 1993) could be explained by a unified mechanism of sensory perception, the premise being that vocal mimicry of sounds is a similar process to the proposed 'frequency-mimicking' of environmental frequencies. This is particularly apposite, as there is currently no evidence that species which mimic human language understand the semantic meaning of the words they utter. ...
Here, I outline the idea of a unified hypothesis of sensory perception, developed from the theoretical vibrational mechanism of olfaction, which can be applied across all sensory modalities. I propose that all sensory perception is based upon the detection of mechanical forces at a cellular level, and the subsequent mechanotransduction of the signal via the nervous system. Thus, I argue that the sensory modalities found in the animal kingdom may all be viewed as being mechanoreceptory, rather than being discrete neurophysiological systems which evolved independently of each other. I go on to argue that this idea could potentially explain language evolution, with birdsong being an example of a more simple form of non-Saussurean language that employs ‘frequency-mimicking’ to produce a vocal signal which describes acoustic, chemical and electromagnetic vibrational frequencies detected within in the environment. I also give examples of how this hypothesis could potentially explain phenomena such as vocal mimicry in animals, as well as the human perception of musicality and the occurrence of synaesthesia; a condition found in humans, where the stimulation of one sensory modality results in the stimulation of another. For example, auditory stimuli are detected and are heard as an acoustic signal, as well as being perceived as colour by the visual system.
... Learning song features from heterospecifics has been demonstrated experimentally in several other songbird species that do not typically do so in the wild, such as song sparrows (Melospiza melodia), swamp sparrows (Melospiza georgiana), white-crowned sparrows (Zonotrichia leucophrys), zebra finches (Taenopygia guttata) and Bengalese finches (Lonchura striata) (Marler and Peters 1977;Clayton 1989;Marler 1997;Soha and Marler 2000;Kelley et al. 2008). A particularly similar result to the present study was found by Clayton (1989) in zebra finches, which when tutored with phrase-repeating Bengalese finches learned to repeat phrases, although not to the extent that Bengalese finches do. ...
We analyse data from a cross-fostering experiment in which house finches were fostered by canary parents. Some individuals received canary song input, while others received no input, after a period of masking noise. We compare audio recordings of songs by these individuals to each other and to species-typical house finch and canary songs. Canary-tutored house finches learn to trill as part of their song. Since trills are not present in typical house finch song, naturally occurring song patterns underestimate what a species is capable of learning and producing. These results highlight a potential avenue for the origin of novel syntax in songbirds.
... However, there is little experimental evidence that songbirds mimic in functionally important ways. In some species, mimicked call types are used in inappropriate contexts (Kelley et al. 2008). ...
I investigated the vocal repertoire of Blue Jays using observational and experimental methods.
... Some birds have also evolved acoustic Batesian mimicry that simulates the sound of a toxic, inedible, or more dangerous species so as to gain security benefits (Gaul, 1952;Sibley, 1955;Klump and Shalter, 1984;Apel and Weise, 1986;Rowe et al., 1986;Owings et al., 2002;Kelly et al., 2008;Zub et al., 2017). When a female bird like a great tit (Parus major) senses the presence of a predator, the bird stretches its wings forward and down rapidly in a curve, raises and extends its tail, and gives a spontaneous hissing call (Perrins, 1979;Cramp and Perrins, 1994) that leads to its misidentification as a snake by the predator, which is then discouraged from approaching (Cox, 1930;Sibley, 1955;Rowe et al., 1986;Perrins, 1979;Krams et al., 2014). ...
Nest predation often leads to breeding failure and is an important component of natural selection that affects the
evolution of nest defense behavior in birds. Many tit species give a hissing call as nest defense, but there are few
studies of interspecific variation in hissing calls, and whether these are related to nest predation and nesting
success. In this study, we compared the hissing calls of five tit species including cinereous tits (Parus cinereus),
marsh tits (Poecile palustris), varied tits (Sittiparus varius), willow tits (Poecile montanus), and coal tits (Periparus
ater) in Saihanba National Forest Park in Hebei and Xianrendong National Nature Reserve in Liaoning. In
Saihanba of Hebei, the proportion of cinereous, willow, and coal tit individuals giving a hissing call differed
significantly but the rate of nest predation was similar. It was also true for the three tit species (cinereous, varied,
and marsh tits) in Xianrendong of Liaoning. Cinereous and varied tits showed no differences in clutch size, date
of the first egg, nest predation and nesting success between individuals that gave and those that did not give a
hissing call. These results indicate that for tit species that breed in nest boxes distributed within the same area,
there is interspecific variation in hissing calls but this variation is not significantly correlated with nest predation
risk.
... This does not seem to be the case here, because there were no other signs of aggressive interactions, and overlapping occurred between individuals from the same social unit that we would expect to also engage in cooperative caring of calves. Instead, these vocal exchanges could function to affirm the shared unit and/or clan membership of the whales involved (Schulz et al. 2008), in a similar manner as affiliative signals in birds (Kelley et al. 2008). Rapidly and synchronously matching a shared coda type effectively signals a shared repertoire and hence probable social affiliation (Schulz et al. 2008). ...
Among large variations in size, habitat use, trophic niche, and social systems of toothed whales, one species—the sperm whale—stands out as an animal of extremes. The world’s largest biological sonar operated by the largest brain on Earth shapes much of sperm whales’ lives as efficient predators, exploiting massive biological resources at great depths. They are nomads with home ranges spanning thousands of kilometers horizontally and more than a kilometer vertically. These three-dimensional movements and extremely low reproductive rates place a premium on cooperative calf care, making it central to the tight matrilineal social units of female sperm whales in tropical and subtropical waters. The social units themselves are elements of sympatric cultural clans with distinctive behaviors and vocal dialects. Males leave their maternal units in their teens, gradually moving to higher latitudes and becoming less social until, when very much larger than the females, they make periodic forays to warmer waters for mating. New technology is beginning to give us insight into the behaviors of this extraordinary animal, but its long life span means that long-term studies using simple methods are still immensely valuable.
... Much like the superb lyre-bird of Australia, the mockingbird species is an exceptional mimic who is capable of reproducing various species as well as complex and "unnatural" human-made machines such as chainsaws or cell phones. While mating and defense of territory appear to be clear functional reasons for this behaviour, the exact range of explanations remains an open area of research, with debates on the extent to which the behaviour results from learning or from evolutionary convergence (Kelley et al. 2008). The fact that mimids themselves integrate both machine and biological sources points to sonic mimicry as a well-articulated entry point into examining emergent intelligences in environments that integrate both biological and technological agents. ...
... Unlike humans, the vocal range of the black-capped chickadee does not appear to change during development nor differ between the sexes (Ficken, Ficken & Witkin, 1978). In addition, although black-capped chickadees are vocal learners (Nowicki, 1989), chickadees do not copy the vocalizations of other species or environmental sounds, an ability known as vocal mimicry (Kelley et al., 2008). Vocal mimicry might be important in octave equivalence perception for species that are vocal mimics (even if, like chickadees, they do not have individually differing vocal ranges), since mimicking environmental or biological sounds could require imitating sounds that occur outside of one's own vocal range. ...
Octave equivalence describes the perceived similarity of notes separated by an octave or a doubling in frequency. In humans, octave equivalence perception is used in vocal learning, enabling young children to approximate adult sounds where the pitch lies outside of their vocal range. This makes sense because the octave is also the first harmonic of any tonal sound including the human voice. We hypothesized that non-human animals may also need octave equivalence perception in vocal mimicry, the copying of other species or environmental sounds, to approximate sounds where the pitch lies outside their vocal range. Thus, in the current study, we tested budgerigars ( Melopsittacus undulatus ), a vocal mimicking species, for octave equivalence perception. Budgerigars were trained and tested in a go/no-go operant task previously verified in humans. Budgerigars did not show evidence of octave equivalence perception. This result suggests that vocal-mimicking does not necessarily facilitate or presuppose octave equivalence perception.
... Pasteur (1982), for example, rejected vocal mimicry as a form of mimicry because it is learned. However, vocal mimicry is not necessarily learned (Kelley et al. 2008). Burrowing owls (Athene cunicularia) imitate the sounds produced by rattlesnakes without having ever encountered a rattlesnake and without the need to learn those sounds from other burrowing owls. ...
Despite decades of study, mimicry continues to inspire and challenge evolutionary biologists. This essay aims to assess recent conceptual frameworks for the study of mimicry and to examine the links between mimicry and related phenomena. Mimicry is defined here as similarity in appearance and/or behavior between a mimic and a model that provides a selective advantage to the mimic because it affects the behavior of a receiver causing it to misidentify the mimic, and that evolved (or is maintained by selection) because of those effects. Mimics copy cues or signals that are already in use as part of a stable communication system, but offer misleading information to receivers. Mimicry overlaps, both conceptually and evolutionarily, with camouflage and perceptual exploitation but the overlap is only partial, which may create some confusion. Certain types of camouflage (e.g. masquerade) conform to the definition of mimicry, while others (e.g. background matching) are not considered mimicry because they prevent detection rather than recognition of the camouflaged animal. Mimicry, on the other hand, works by exploiting peculiarities of the receiver at higher stages of sensory processing involving recognition and classification of stimuli. Perceptual exploitation models of trait evolution are also closely related to mimicry, and sensory traps in particular may act as a precursor for true mimicry to evolve. The common thread through these diverse phenomena is deception of a receiver by a mimic. Thus receiver deception (i.e. perceptual error) emerges as a key characteristic of mimicry shared with some types of camouflage and perceptual exploitation.
... Passeriformes (BAYLIS, 1982). Kelley et al. (2008) propõem que a mimecria pode afastar competidores e ameaças, sinalizar intenções para parceiros ou atrair outras espécies, relacionando-se com contextos sociais e ecológicos (HINDMARSH, 1984), e evoluiu por meio de seleção natural e sexual (GOODALE & KOTAGAMA, 2006 ...
Introdução: Os peixes apresentam a maior diversidade entre os vertebrados,
sendo um grupo de suma importância nas análises de toxicidade ambiental, pois
exibem ampla distribuição geográfica, podendo encontrá-los em diferentes
ambientes, e ocupando diversos níveis tróficos da cadeia alimentar. Deste modo,
são considerados como bons bioindicadores da qualidade ambiental (MELA, 2004).
De acordo com Jesus e Carvalho (2008), o sistema imune dos peixes é bem
desenvolvido, e atua frente à contaminação ambiental, por isso, diversos
parâmetros imunológicos podem ser potencialmente empregados como
biomarcadores, como a presença dos centros de melanomacrófagos. Os centros de
melanomacrófagos são encontrados em vários vertebrados não mamíferos, como
répteis, anfíbios e peixes; nos quais, constituindo em agregados de células e
fragmentos semelhantes aos macrófagos, derivados de células fagocitadas,
principalmente eritrócitos e pigmentos como melanina, hemosiderina, ceróides e
lipofuscina; e localizados no tecido reticuloendotelial de órgãos hemolinfopoiéticos,
como fígado, baço e rim (MELA, 2004; PASSANTINO et al., 2014).
Objetivo: O presente trabalho consiste em descrever algumas estruturas
histológicas do tecido hepático, do peixe teleósteo neotropical Steindachnerina
notonota, espécie detritívora.
This handbook lays out the science behind how animals think, remember, create, calculate, and remember. It provides concise overviews on major areas of study such as animal communication and language, memory and recall, social cognition, social learning and teaching, numerical and quantitative abilities, as well as innovation and problem solving. The chapters also explore more nuanced topics in greater detail, showing how the research was conducted and how it can be used for further study. The authors range from academics working in renowned university departments to those from research institutions and practitioners in zoos. The volume encompasses a wide variety of species, ensuring the breadth of the field is explored.
We perceive color everywhere and on everything that we encounter in daily life. Color science has progressed to the point where a great deal is known about the mechanics, evolution, and development of color vision, but less is known about the relation between color vision and psychology. However, color psychology is now a burgeoning, exciting area and this Handbook provides comprehensive coverage of emerging theory and research. Top scholars in the field provide rigorous overviews of work on color categorization, color symbolism and association, color preference, reciprocal relations between color perception and psychological functioning, and variations and deficiencies in color perception. The Handbook of Color Psychology seeks to facilitate cross-fertilization among researchers, both within and across disciplines and areas of research, and is an essential resource for anyone interested in color psychology in both theoretical and applied areas of study.
Vocal mimicry can develop either through imitation of heterospecific models (primary mimicry) or through imitation of conspecifics already producing mimetic song (secondary mimicry). Distinguishing primary versus secondary mimicry is important from ecological, evolutionary, and neurobiological perspectives. We outline four empirical strategies for researchers to detect the usage of secondary mimicry: (1) model selection strategy (heterospecific model commonly mimicked but rare or absent locally), (2) usage frequency strategy (syllable types commonly mimicked but rarely used by the model), (3) acoustic structure strategy (acoustic divergence in how a syllable type gets produced by mimics versus models), and (4) syntax strategy (consistent variation between mimic and model in the ordering of syllable types). We then use these strategies to produce evidence for secondary mimicry in northern mockingbirds ( Mimus polyglottos ), focusing mostly on the mimicked songs of northern cardinals ( Cardinalis cardinalis ) and tufted titmice ( Baeolophus bicolor ). As further evidence of the mechanisms by which secondary mimicry might occur, we also demonstrate that mockingbirds match countersing much more frequently in response to conspecifics versus heterospecifics. Deeper questions about the precise extent of primary versus secondary mimicry in mockingbirds and other mimicking species still need answers.
Vocalisations play a key role in the communication behaviour of many vertebrates. Vocal production requires extremely precise motor control, which is executed by superfast vocal muscles that can operate at cycle frequencies over 100 Hz and up to 250 Hz. The mechanical performance of these muscles has been quantified with isometric performance and the workloop technique, but due to methodological limitations we lack a key muscle property characterising muscle performance, the force-velocity (FV) relationship. Here we quantify the FV relationship in zebra finch superfast syringeal muscles using the isovelocity technique and test if the maximal shortening velocity is different between males and females. We show that syringeal muscles exhibit high maximal shortening velocities of 25 L0 s−1 at 30°C. Using Q10-based extrapolation, we estimate they can reach 37-42 L0 s−1 on average at body temperature, exceeding other vocal and non-avian skeletal muscles. The increased speed does not adequately compensate for reduced force, which results in low power output. This further highlights the importance of high frequency operation in these muscles. Furthermore, we show that isometric properties positively correlate with maximal shortening velocities. While male and female muscles differ in isometric force development rates, maximal shortening velocity is not sex dependent. We also show that cyclical methods to measure force-length properties used in laryngeal studies give the same result as conventional stepwise methodologies, suggesting either approach is appropriate. We argue that vocal behaviour may be affected by the high thermal dependence of superfast vocal muscle performance.
Birdsong provides a fascinating system to study both behavioral and neural plasticity. Oscine songbirds learn to sing, exhibiting behavioral plasticity both during and after the song-learning process. As a bird learns, its song progresses from a plastic and highly variable vocalization into a more stereotyped, crystallized song. However, even after crystallization, song plasticity can occur: some species' songs become more stereotyped over time, whereas other species can incorporate new song elements. Alongside the changes in song, songbirds' brains are also plastic. Both song and neural connections change with the seasons in many species, and new neurons can be added to the song system throughout life. In this review, we highlight important research on behavioral and neural plasticity at multiple timescales, from song development in juveniles to lifelong modifications of learned song.
Studies of the acoustic structure of song in young birds have proven valuable at helping us understand song development, but nearly all existing studies have been performed on non-mimicking songbirds. We conducted a cross-sectional field study of song development in a prominent vocal mimic, the northern mockingbird, by comparing the fall songs of hatch-year vs. after-hatch-year birds. Although sample sizes of hatch-year birds were small, the data suggest a developmental trajectory in which both song stereotypy and the frequency of vocal mimicry increase with age. Thus, the acoustic structure of fall song may provide a reliable indicator of a bird’s age and performance.
Vocal learning is an ability that has only evolved in a handful of taxa. Songbirds learn their songs, and some species have flexible learning in which they not only incorporate species-specific sounds, but heterospecific and/or environmental sounds as well. The functions of vocal mimicry are still unknown for many species and studying mimicry can teach us about the variation within the song learning process. In this thesis, I focused on five hypotheses on how mimicry could function in sexual selection. The repertoire size hypothesis suggests that selection for larger repertoire sizes allows mimicry to occur because imitation can increase repertoire size. The permissive learning hypothesis states that heightened song complexity requires a relaxed song template, which may allow passive use of mimicry. The learning and performance hypothesis suggests that learning ability and song or performance quality are honest signals of a singer’s quality and that listeners may focus on mimicry to assess individuals. The fourth and fifth hypotheses, which have received very little attention, are the structural function and acoustic function hypotheses, which suggest that mimicry has an as-yet-unknown structural or acoustic role in song, respectively. In these cases, mimetic accuracy does not matter; rather imitations and species-specific vocalizations are used in different ways. I explored these hypotheses using European starling (Sturnus vulgaris) song. Instead of testing the evolutionary functions of mimicry directly, I concentrated on the structural mechanics of mimicry in song. This approach allowed me to indirectly test whether mimetic and nonmimetic song components have the same functional effect. Chapter I is an overview of the more than 300 songbird species that are vocal mimics and shows that mimicry evolved repeatedly throughout the evolution of the songbird clade. The next three chapters are a detailed case study of the vocal mimicry of European starlings. In chapters II through IV, I use a combination of structural and acoustic analyses to emphasize the ways in which mimicry functions in starling song. I show that mimicry is treated differently from species-specific sounds, although in subtle, structural ways, and it remains unclear how important the inclusion of mimicry is to listeners. Advisor: Daizaburo Shizuka
Vocal mimicry is taxonomically widespread among birds, but little is known about mimicry of non-avian models. Prior studies show preferential imitation of avian models whose sounds are acoustically similar to the non-imitative songs of the vocal mimic. Based on these studies and anecdotes about frog imitations by northern mockingbirds (Mimus polyglottos), we hypothesized which anuran models would be most likely to get imitated by mockingbirds across their geographic range. We tested our hypothesis using >40 hours of archived mockingbird recordings. Our results showed that mockingbirds imitated at least 12 anuran species, and calls were disproportionately mimicked when they contained dominant frequencies within the vocal range of the mockingbird (750-7000 Hz). Mockingbirds also frequently modified model anuran sounds by leaving out formants and/or truncating call duration. Our results represent the most comprehensive survey for any mimicking species of the imitation of anurans.
Ecogeographic analyses have recovered common environmental trends with respect to morphology; however discrepancies among trends exist. Hypothesized reasons for these divergences vary, but most relate a taxon's morphology to its ecological niche. Morphology is known to diverge when species co‐occur with competitors or predators and when species occur across different habitats and environments. A less understood divergence from ecogeographic trends is niche fixation, wherein species become locked into particular niches due to their community interactions or foraging ecology. A form of niche fixation has been hypothesized in the theory of Interspecies Social Dominance Mimicry (ISDM), in which mimics maintain relatively constant size ratios with models to perpetuate their mimicry. If true, mimics should display variation and trends in tandem with their models. Here, I use mass as a proxy for body size and examine ecogeographic trends in two sets of woodpeckers (Picidae): a Nearctic group which has been reported to interact via ISDM, and a Neotropical group which, based on similar appearances and overlapping distributions, is a potential ISDM system. I found ecogeographic trends suggestive of differential evolutionary responses, and I found evidence against niche fixation in the Nearctic clade. The Neotropic clade showed limited evidence for tandem size evolution between models and mimics, but inconsistencies in the size ratios between mimic and model populations. Here, I discuss the implications of observing divergent ecogeographic trends within mimicry systems, with specific emphasis on how environment, ecology, and community interactions guide evolution.
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Mimetic songs of superb lyrebirds, Menura novaehollandiae, were investigated to evaluate the effects of population and age class on model selection and mimetic accuracy. Two geographically isolated populations with similar habitat and sympatric avian species mimicked the same vocalizations from almost identical species of avian models and failed to mimic the same suite of potential models. Mimetic song had a similar structure at the two sites: diversity of song items and performance rate were not significantly different. However, the populations differed in the frequency some models were repeated in a bout of song. We compared the acoustic structure of lyrebird copies to the physically challenging song of the eastern whipbird, Psophodes olivaceus, and the complex contact call of the yellow-tailed black cockatoo, Calyptorhynchus funereus. Lyrebirds could not match the duration of the sustained monotone note of the whipbird nor the demanding frequency bandwidth of the explosive whipcrack. There was a significant positive correlation between whipcrack bandwidth and diversity of mimetic items which suggests consistent individual differences in mimetic performance. Contact calls of cockatoos and lyrebird copies were also distinguishable but less so than with the whipcrack. Subadults made much poorer copies of these models than did the adult lyrebirds and had fewer identifiable heterospecific song items suggesting that costs are associated with the development of mimetic song. Together, these findings are consistent with a female choice hypothesis where females prefer males that mimic more accurately and have a greater diversity of mimetic items, but experimental verification is needed.
To date, song research has focused primarily on the interactions of conspecifics. However, frequent interactions of songbirds with heterospecifics may necessitate adequate communication outside the species boundary. In this study, we focus on heterospecific communication behaviour of two small sympatric congeneric passerines, great and blue tits (Parus major and Parus caeruleus), which breed in overlapping territories and compete for food and nesting cavities. By means of a first playback experiment, we show that (1) heterospecific matching (imitating songs of the other species) is a strategy frequently used by great tits but not by blue tits, (2) both blue tit trilled and untrilled song can be accurately matched by great tits and that (3) almost half of the great tits in our study population match at least one blue tit song across all studied breeding stages, indicating that this heterospecific matching behaviour is a common feature in this population. A second playback experiment showed that these great tit imitations of blue tit songs do not function in intraspecific communication between male great tits. Hence, these heterospecific imitations appear to be designed for interspecific communication with blue tits. These findings suggest a strong heterospecific influence on the vocal learning process, repertoire composition and repertoire use in great tits and provide a possible mechanism that can drive song convergence in songbirds.
Although heterospecific vocal imitation is well documented in passerines, the evolutionary correlates of this phenomenon are poorly known. Here, we studied interspecific variation in vocal mimicry in a comparative study of 241 European songbirds. We tested whether vocal mimicry is a mode of repertoire acquisition or whether it resulted from imperfect song learning. We also investigated the effect of the degree of contact with the vocal environment (with species having larger ranges, abundance, or being long lived having a higher degree of mimicry) and a possible link with cognitive capacity (an overall larger brain in species with mimicry). Finally, we determined the potential evolutionary role of vocal mimicry in different interspecific contexts, predicting that mimicry may affect the intensity of brood parasitism, predation, or degree of hybridization. While controlling for research effort and phylogenetic relationships among taxa, we found that effect sizes for intersong interval, brain size, breeding dispersal, abundance, age-dependent expression of repertoires, and predation risk reached a level that may indicate evolutionary importance. Vocal mimicry seems to be a consequence of song continuity rather than song complexity, may partially have some cognitive component but may also be dependent on the vocal environment, and may attract the attention of predators. However, estimates of sexual selection and interspecific contacts due to brood parasitism and hybridization varied independently of vocal mimicry. Therefore, mimicry may have no function in female choice for complex songs and may be weakly selected via interspecific associations. These findings provide little evidence for vocal mimicry having evolved to serve important functions in most birds. Copyright 2007, Oxford University Press.
It is suggested that characters which develop through mate preference confer handicaps on the selected individuals in their survival. These handicaps are of use to the selecting sex since they test the quality of the mate. The size of characters selected in this way serve as marks of quality. The understanding that a handicap, which tests for quality, can evolve as a consequence of its advantage to the individual, may provide an explanation for many puzzling evolutionary problems. Such an interpretation may provide an alternative to other hypotheses which assumed complicated selective mechanisms, such as group selection or kin selection, which do not act directly on the individual.
The budgerigar, a small species of parrot, can learn new vocalizations throughout life and is therefore widely used as a model system for studying various aspects of vocal learning. It is not known, however, why parrots imitate sounds. To test the hypothesis that vocal imitation in budgerigars is related to pair bonding, we recorded approximately 100 contact calls from each of nine male and nine female adult budgerigars that were unfamiliar with one another and then placed them into pairs. We sampled their contact call repertoire weekly and conducted twice-weekly behavioural observation sessions. We compared contact calls by sonagram cross-correlation and classified them by means of a hierarchical clustering algorithm. This analysis showed that all pairs developed a shared call within an average of 2.1 weeks. Further analysis revealed that eight of the nine male budgerigars imitated the contact calls of their assigned mates, while none of the females imitated the calls of their males. We conclude that contact call imitation in adult budgerigars probably contributes to pair bond formation and maintenance. Prior studies on budgerigars were limited by the lack of a behavioural paradigm to elicit vocal imitation reliably. Our study remedies this and thereby serves as a foundation for future studies on vocal learning in adult animals. Copyright 2000 The Association for the Study of Animal Behaviour.
Phainopeplas (Phainopepla nitens) utter contact calls, loud distress screams, and 37 other distinguishable vocalizations when captured, including imitations of at least 12 species. In southern California, Phainopeplas captured in the desert and coastal woodlands imitated species from both regions, suggesting that individuals occupy both habitats during the year and have an extended period of learning that spans the period of time when they move between regions. There was no significant difference in the number of calls imitated based on sex, male age, or habitat. A high percentage of Phainopeplas in both desert and coastal woodlands imitated Red-tailed Hawks (Buteo jamaicensis) and Northern Flickers (Colaptes auratus), whereas the use of other species' calls varied with habitat. Phainopeplas did not simply imitate the calls of the most abundant species or those that were most vocal.
Bird song is an acoustic ornament. That is, bird song is a conspicuous, elaborate trait with no apparent survival value. Thus, along with long tails and showy plumage, bird song has been extensively studied as a model of avian sexual selection. There has now accumulated much experimental evidence, from both field and laboratory studies, that song functions to attract mates and to repel competitors from territories (Kroodsma and Byers, 1991; Searcy and Andersson, 1986). One of the most conspicuous and elaborate aspects of bird song is its extreme complexity and variety. Individuals of many species of birds sing multiple variants of their species-typical songs; that is, they possess song repertoires. Large song repertoires are the acoustic analogue of a peacock’s tail. Because songs are so showy and seem so redundant, much research has been devoted to describing song repertoires and patterns of singing behavior. Similarly, many researchers have hypothesized ways in which sexual selection may favor birds that have larger song repertoires. The purposes of this paper are to (1) review the distribution of song repertoires in passerine birds and (2) review the numerous hypotheses that have been proposed to account for the evolution of song repertoires.
We document cases of Eastern Towhees (Pipilo erythrophthalmus) using mimicked alarm calls from three presumptive models [Blue Jay (Cyanocitta cristata), Brown Thrasher (Toxostoma rufum), and American Robin (Turdus migratorius)]. In four instances, male towhees employed heterospecific calls without substitution in their own call repertoires. Three birds (New Jersey, New York) used jay-like calls mixed with 'Chewink' calls in the same bouts of calling. One bird (New York) increased the frequency of its mimicked call during intense reactions to disturbance (high rate of calling). A Texas towhee employed jay-like and Chewink calls separately in different contexts. In another case, sequences of robin-like alarm calls were used by a towhee to form unusual, distinctive song-types during bouts of singing. These observations suggest that some aspects of towhee alarm call repertoires may be influenced by auditory learning, and that mimicked alarm calls also can be incorporated into song repertoires.
AI3STRACT.--Male Satin Bowerbirds (Ptilonorhynchus violaceus) court females at specialized structures called bowers. Courtship includes a complex pattern of vocalizations in which a broad-band, mechanical-sounding song is followed by interspecific mimicry. We studied the effect of male courtship displays on male mating success in Satin Bowerbirds. Data from 2 years of field research showed low between-male differences in mechanical components of courtship song and high variability between males in mimetic singing. Older males sang longer and higher-quality bouts of mimicry than did younger males. In one year, courtship song features were correlated with male mating success. The results suggest that female Satin Bowerbirds use male courtship vocalizations in their mate-choice decisions. We discuss hypotheses about assessment of male age and dominance from courtship vocalizations and suggest that these songs have evolved as a result of selection for male display characteristics that provide females with information about the relative quality of prospective mates. Re- MALE Satin Bowerbirds (Ptilonorhynchus vio-laceus) build specialized structures called bow-ers that are used as sites for courting females and for mating (Vellenga 1970, Donaghey 1981, Borgia 1985). Females raise their young unas-sisted by males, and males do not associate with females after mating. Males decorate their bowers with a variety of natural objects and attempt to steal decorations and destroy the bowers of other males.
A series of playback experiments was carried out to determine whether territorial male song sparrows could discriminate between their own species song, and the same song produced by a white-crowned sparrow. In two out of three measures of response, the males did not discriminate between model and mimic song. In constrast, most males showed no response to control white-crowned sparrow song, although two individuals showed a strong interspecific response. Other examples of interspecific aggression were also detected during the experiments. The results are discussed in relation to recent studies on interspecific song learning and the competition hypothesis of vocal mimicry in songbirds.
The results of a study of starling vocal mimicry are summarised and discussed in relation to various possible functional explanations of mimicry. Only one, a hypothesis based on sexual selection, is not rejected outright and even this was seen to have problems. A dif ferent approach yielded a causal hypothesis based on mistakes made during song learning. This causal hypothesis is consistent with all known features of starling mimicry, and can readily be extended to other species, but is probably not consistent with any of the candidate functional hypotheses, including the one based on sexual selection. It is tentatively concluded that there is no additional functional explanation of starling vocal mimicry.
Examined the extent song repertoires and singing behaviour of Fringilla coelebs evolved as a means by which resident birds deceive intruders into overestimating the density of residents, making the area appear less suitable for settlement. The chaffinches did not show a significant tendency to change song posts synchronously any more than would be expected by chance. About 90% of song type/song post changes were asynchronous. Half of the birds did not repeat their song types with equal frequency, nor did they distribute their singing effort evenly over all the song posts. The degree of similarity between song types in the same repertoire and the degree of similarity between song types from different individuals were not significantly different. No correlation between song rate and repertoire size was found, though seasonal biases strongly restricted this facet of the investigation. It is concluded that the evolution of repertoires and singing behaviour in chaffinches seems unlikely to have occurred in conformity with the Beau Geste hypothesis.-from Authors
Animal sound production has proved a very useful model for studies on vertebrate brain function, especially as the means exist for producing unbiased records of the behaviour. Birds are particularly suitable for this type of study. The midbrain seems to be very important in the production of vocalizations. However, the exact role of the midbrain structures involved, once thought to be understood, has recently been questioned.
Unrecognized different definitions for the same term can produce confusion among workers in a field. A review of over 80 definitions of bird song shows little agreement as to what defines bird song or differentiates it from calls. Defining criteria have included structural (e.g. duration), delivery (e.g. rhythmic production), physiological (e.g. hormonal control), developmental (e.g. learning), functional (e.g. territoriality), affecftive (e.g. musicality), and taxonomic (e.g. restriction to passerines) attributes of song. Each criterion has been rejected by some authors. Song definitions often are qualified with exceptions and include such qualifters as "largely arbitrary", "unclear", "not very precise", etc. Song concepts have changed over time and will continue to do so. A single song definition that covers all extant song concepts is not possible. The various song concepts serve different purposes and will be most useful if kept distinct and appropriately labeled.
Previous studies of Sturnus vulgaris song have shown that two basic categories, one composed of simple and loud songs (whistles) the other of long quiet and complex songs (warbles) can be recognized in the repertoires of all males. It is suggested that the starling possesses two type of "templates' in its species-specific song which are reflected in its mimicries with quite different degrees of selectivity. These two categories of mimicries may have evolved for functional reasons that are linked to the corresponding functions of the species-specific songs themselves. -from Authors
A high frequency of rapid predator approach to broadcast fear screams supports the predator attraction hypothesis in explaining the function of screaming. A high incidence of screaming in prey species that are relatively large in relation to their main predators and live in densely vegetated habitats is concordant with this view. Fear screaming is thus a nonaltruistic phenomenon and is not maintained through kin selection. -from Author
In many species, mating preferences are acquired by sexual imprinting. This process may lead to a preference for a partner that is slightly novel. An asymmetrical preference for novel partners might provide a mechanism driving evolutionary change in the characteristics used in mate choice. -from Authors
Bird song is one of the most remarkable and impressive sounds in the natural world, and has inspired not only students of natural history, but also great writers, poets and composers. Extensively updated from the first edition, the main thrust of this book is to suggest that the two main functions of song are attracting a mate and defending territory. It shows how this evolutionary pressure has led to the amazing variety and complexity we see in the songs of different species throughout the world. Writing primarily for students and researchers in animal behavior, the authors review over 1000 scientific papers and reveal how scientists are beginning to unravel and understand how and why birds communicate with the elaborate vocalizations we call song. Highly illustrated throughout and written in straightforward language, Bird Song also holds appeal for amateur ornithologists with some knowledge of biology.
Using playback experiments, I tested whether distress calls by phainopeplas attract heterospecifics and elicit mobbing of a predator decoy. Phainopeplas use two types of distress calls: loud scream calls and mimicry of other species' vocalisations. Screams and imitations together attracted significantly more heterospecifics than in the absence of distress calls. When broadcast alone, scream calls were more effective at eliciting heterospecific approach and mobbing behaviour than were imitations. Birds were significantly more likely to mob the predator decoy during broadcast of screams and imitations than during broadcast of screams with digitally scrambled imitations, even though there was no significant difference between treatments in the number of birds initially approaching. This suggests that precise mimicry does not play a key role in attracting heterospecifics but may elicit increased mobbing once they have arrived. Mimicry did not appear to be directed at the species whose calls were imitated; only 4 of the 19 species responding to distress calls were model (mimicked) species, and birds mobbed the predator decoy regardless of whether imitations of their own calls were used in playback trials.
Resumen. Al ser capturada, Phainopepla nitens emite llamadas de contacto, fuertes gritos de angustia, y otras 37 vocalizaciones diferentes, incluyendo imitaciones de al menos 12 especies. En el sur de California, individuos de P. nitens capturados en el desierto y en bosques costeros imitaron especies de aves de ambas regiones, sugiriendo que los individuos ocupan ambos ambientes a lo largo del año y que tienen un período de aprendizaje que abarca el tiempo en que se mueven entre regiones. No hubo diferencias significativas en el número de llamadas imitadas considerando sexo de los individuos, edad de los machos, o ambiente. Un alto porcentaje de P. nitens, tanto en el desierto como en los bosques costeros, imitó a Buteo jamaicensis y Colaptes auratus, mientras que el uso de llamadas de otras especies varió con el ambiente. P. nitens no imitó simplemente las llamadas de las especies más abundantes o de aquellas que vocalizaron más.
A distinction is made between fitness-enhancing aspects of a trait and selective forces that result in its optimization. Any functional explanation conceived to account for the occurrence of mobbing behavior must explain the benefits both for the initiator and for the birds joining it. Nine teleonomic hypotheses are proposed that permit predictions about the behavior of the prey and/or the predator in terms of mobbing or its subsequent effects on the behavior of both parties. Predictions of different hypotheses refer to different aspects of mobbing when prey and predator are considered concurrently. Only 2 hypotheses lead to contrasting predictions (i.e., to "strong inference tests"). The weakness of the teleonomic method is that it does not enable determination of when the list of possible functions of a behavior is exhausted. (Germany summary) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
I briefly discuss the major current hypotheses which have been put forward to explain the apparently redundant song repertoires of many oscine birds: individual recognition; sexual selection; matched countersinging; and habituation. I then propose an alternative idea, that song repertoires in some species have evolved in the context of density assessment. In the great tit, non-territorial birds use the song of residents as a cue in assessing density, and I suggest that repertoires are used by resident birds to increase the apparent density of singing residents, and hence decrease the apparent suitability of the area to new birds. I explore some implications of the idea and list some predictions.
This paper presents the first extensive evidence of vocal imitations of African birds by a Palaearctic migrant, the Marsh Warbler Acrocephalus palustris . Nearly 30 individual tape recorded repertoires have been analysed, most of them from Belgium; imitations of each identified species were compared to models by spectrographic analysis. A list of 113 African species (33 non‐passerines, 80 passerines) was thus established (Appendix), which, added to the list of 99 European species, gives a total imitative range of 212 species. The low‐pitched voices of many non‐passerines exclude them from imitation.
Vocal imitations of some rather local species in East Africa provide information on the localization of the autumn and winter quarters of A. palustris . In particular, the frequency of imitations of such species as Vinaceous Dove Streptopelia vinacea , Boran Cisticola Cisticola bodessa and Red‐pate Cisticola C. ruficeps lends support to the idea of the existence of autumn quarters in northeastern Africa.
Individual repertoires contain an average of 76.2 different imitated species (extremes 63–84), the number of African species (average 45.0) exceeding that of European species (average 31.2). About a fifth of the complete song remains unidentified and probably corresponds to imitations of African birds whose voices have not yet been recorded. The most recurrent imitations are those of noticeably noisy species, widespread in Africa. A. palustris appears not to be selective in its repertoire. Imitations of different species can, to some extent, be combined and alternated into original motifs.
Circumstantial evidence indicates that the young A. palustris are still learning song motifs when on their way to their winter quarters and probably stop learning soon after their arrival there, most of them in January, at the age of 6–7 months. There is a temporal separation between the sensitive phase and the motor phase of song learning.
No conclusion as to the possible functions of the imitative element of the song can be drawn at present.
Four hypotheses were tested for explaining interspecific mimicry observed in African Cossypha robin-chats. (1) The five robin species imitate similar models. (2) Natal Robin imitations reflect the acoustic environment within their habitat. (3) Natal Robins imitate competitor species. (4) Natal Robins imitate predators and brood parasites. The study included analysis of extensive collections of sound recording of these five species, as well as recordings of the Natal Robin Cossypha natalensis obtained in the field. The robin species mimicked different species groups, in accordance with their acoustic environment. This also applied to different Natal Robin populations. Only hypothesis (2) was confirmed, the others being refuted. It appears that bird species with simple calls have a greater probability of being mimicked. Our results were consistent with Hartshorne's prediction that song versatility increases with song duration.
Vier Hypothesen zur Erklärung interspezifischer Mimikry bei afrikanischen Rötel der Gattung Cossypha wurden getestet: (1) Die fünf untersuchten Arten imitieren ähnliche Modelle. (2) Natalrötel imitieren das akustische Umfeld ihres Habitats. (3) Natalrötel imitieren konkurrierende Arten. (4) Natalrötel imitieren Prädatoren und Brutparasiten. Dazu wurden zahlreiche im Feld aufgenommene Tonaufnahmen der fünf Rötelarten analysiert. Die Arten imitierten verschiedene Artengruppen, welche das jeweilige akustische Umfeld widerspiegeln. Dies gilt auch für unterschiedliche Populationen. Nur Hypothese (2) konnte unterstützt werden, die restlichen Hypothesen wurden verworfen. Vogelarten mit einfachen Rufen scheinen mit größerer Wahrscheinlichkeit imitiert zu werden. Unsere Ergebnisse sind in Einklang mit Hartshornes These, dass die Vielseitigkeit des Gesanges mit der Länge des Gesanges zunimmt.
Great Spotted Cuckoo nestlings were shown, after some days in the nest, to have begging calls that differed depending on whether they were being reared by Magpies or Carrion Crows. They also produced calls of a pitch and repetition rate that implied a high level of hunger.
We conducted interactive playback experiments on foraging flocks of orange-fronted conures, Aratinga canicularis, using loud contact calls that had been recorded at sites ranging from 0 to 30 km from the playback site. Responses were scored on the basis of the proximity of approach to the speaker, the number of different vocalizations produced by the responding flock, and the duration of respondent vocal interactions with the playbacks. Overall response strength decreased significantly as distance between playback and recording sites was increased up to 9 km, and remained at a steady low level for greater distances. As 9 km is the upper limit of conure home ranges measured in this study site, this nonlinear effect of response with distance suggests that response strength is partly determined by familiarity with calls of local birds. An additional and independent amount of the variation in response strength was explained by the structural similarity between respondent and stimulus calls. This correlation could be caused by a preference to interact with known stimulus birds whose calls have converged during prior associations. However, our data suggest that responding birds subtly changed their call structure during longer trials to more closely match the stimulus call. If subsequently verified as a common phenomenon, this finding could provide an important explanation for the remarkable imitative abilities of parrots.
Vocal mimicry by the Black-browed Reed Warbler Acrocephalus bistrigiceps was investigated. To identify mimicry objectively, we measured similarities between the sounds of models and those of Warblers by means of Principal Component Analysis (PCA) using a set of acoustic parameters. Of the sounds suspected of being mimicry according to visual inspection of sonagrams, only 57% were identifiable as mimicry according to PCA. Previous studies have not included quantitative criteria for assessing vocal mimicry, and our results suggest that judgements might not be reliable in the absence of objective criteria. Male Warblers incorporated the mimetic sounds into their songs, and each male mimicked 2–5 species. We found no evidence that females preferred males with large mimetic repertoires. This suggests that vocal mimicry has not evolved in response to selection by females in this species, although our analysis did not reveal entire mimetic repertoires in the Warbler songs.
Burrowing owls nest and roost in ground squirrel burrows, a refuge frequently used by rattlesnakes. When cornered, burrowing owls produce a vocal hiss that has been suggested to mimic a rattlesnake's rattle. To test this hypothesis, we conducted an experiment using two populations of Douglas ground squirrels that differ in their evolutionary histories with rattlesnakes. Both squirrel populations were sympatric with burrowing owls. Squirrels from a population subjected to natural selection by rattlesnakes treated the owl hiss as cautiously as they did the rattle, and responded with greater caution to the rattle and hiss than to two control sounds. Squirrels from a rattlesnake-free area, however, were less systematic in differentiating among the rattle, the hiss, and the control treatments. Such variation between ground-squirrel populations provides evidence that the burrowing owl's defensive hiss currently functions as an acoustic Batesian mimic of a rattlesnake's rattle.
The functions of vocal mimicry were studied in the Chorister Robin Cossypha dichroa. Vocalizations of the mimic and its models were monitored throughout the year. Sound playback experiments documented responses of the mimic to vocalizations of conspecifics and other species. Vocal matching by C. dichroa appears to function as a mechanism for advertising and establishing species identity. Results suggest that C. dichroa song constitutes a potential form of acoustical interference in the vocal communications of other species. Complementary relationships are suggested among complex song, generalized food habits, and interspecific interference or aggression.
Die Funktionen des Spottens wurden am afrikanischen Spottrötel Cossypha dichroa untersucht.
Häufigkeit und Art der Lautäußerungen änderten sich im Verlauf des Jahres. Gesangsschwerpunkte lagen in der Brutzeit, als auch die Reviere am stärksten verteidigt wurden.
Die Intensität der Reaktionen von C. dichroa auf vorgespielte Gesänge war je nach Gesangsform verschieden.
Vorgespielte Gesänge anderer Vögel der gleichen Gegend, die normaler-weise nicht von C. dichroa imitiert werden, brachten keine Reaktionen. C. dichroa schien manchmal auf die Gesänge von Artgenossen und von anderen Gattungen mit ähnlichen Lautäußerungen zu antworten.
Weitere Experimente mit vorgespielten Gesängen ergaben, daß die Vögel auf artfremden Gesang dann spottend antworteten, wenn dieser Gesang schon von einem Artgenossen vorgetragen worden war. Das Spotten scheint zur Revieranzeige und zum Gattungserkennen wichtig.
Die Ergebnisse stützen die Hypothese, daß der Gesang von C. dichroa eine potentielle Form akustischer Einmischung in die Kommunikation anderer Gattungen darstellt. Das kann bei der Nahrungssuche und bei verschiedenen Formen zwischenartlicher Konkurrenz eine Rolle spielen.
At least 44 different song types were recorded in a population of Coal Tits at Klaebu in central Norway. Each male sang up to 14 different types. In testing the Beau Geste hypothesis the following predictions were made: (1) Territorial males tend to change song type when moving from one song post to another. (2) The tendency to change song type when moving from one song post to another increases with the distance between the song posts. (3) Territory holders prefer inconspicuous song posts that reduce the chances of being instantly detected by possible intruders and prospectors. However, none of these predictions were confirmed by the data analyses. The singing behaviour of the Coal Tit does therefore not support the Beau Geste hypothesis.In einer Population der Tannenmeise bei Klaebu, Mittelnorwegen, wurden mindestens 44 unterschiedliche Gesangstypen registriert. Einzelne Mnnchen sangen bis zu 14 Typen. Um die Beau-Geste-Hypothese (ein Snger tuscht durch verschiedenen Gesangstypen die Anwesenheit mehrerer Individuen vor) zu testen, wurden folgende Annahmen geprft: (1) Territoriale Mnnchen neigen dazu, ihren Gesangstyp zu ndern, wenn sie die Singwarte wechseln. (2) Die Tendenz, zwischen Gesangstypen zu wechseln, ist bei Mnnchen am grten, die whrend einer Gesangsphase mehr als eine Singwarte benutzen. (3) Territoriale Mnnchen bentzen unauffllige Singwarten, um nicht so schnell von mglichen Eindringlingen oder reviersuchenden Artgenossen entdeckt zu werden. Die Analyse der Daten ergab jedoch fr keine dieser Annahmen eine Besttigung. Somit untersttzt das Verhalten singender Tannenmeisen die Hypothese nicht.
Contact calls are used to maintain cohesion and coordinate movements in social animals. The amount and type of identity information provided by contact calls are linked to social organization. Socially stable species often converge on shared group-specific contact calls. In socially fluid species, contact calls tend to be individually distinctive; evidence indicates that such calls are important for mediating individual-specific interactions. Dolphins, for example, will mimic the individually distinctive contact calls of other individuals while socializing. We examined contact calls in another fission–fusion species, the orange-fronted parakeet. Free-living and temporarily captive nonbreeding pairs as well as free-living breeding pairs were recorded. In all contexts, pairs produced multiple (up to nine) discrete contact call types, but like dolphins, typically favoured one to two individually specific variants per bird. The number of dominant variants produced and their evenness of use varied with context. Captive pairs produced the fewest dominants, using them with high evenness. Free-living nonbreeding pairs produced more dominants, and showed similarly high evenness. Breeding pairs varied widely in the number of dominants produced and their evenness of use, showing both the highest and lowest values of each. Latent acoustic measures revealed greater structural variation within and among dominants for free-living compared to captive pairs, presumably reflecting the increased opportunity for social interaction available in the wild. Across contexts, calls could be accurately assigned to pair using acoustic measures; however, within-pair call clustering was not greater than that between pairs. Pairs' calls were distinctive, but in a way that preserved individual variation.
Song repertoires in the red-winged blackbird (Agelaius phoeniceus) were studied to test the hypothesis that song repertoires have evolved to mimic high density. Results were consistent with predictions of this hypothesis. (1) Song types within a repertoire were as variable as those sung by different males. (2) Males often switched song type when they switched perch. (3) Males with large repertoires sang at faster rates than those with small repertoires, but repertoire size did not affect bout length or bout rate. (4) Rate of habituation was a function of repertoire size. (5) Empty territories occupied by speakers broadcasting song repertoires were more successfully defended than those occupied by speakers broadcasting single song types. These results are also consistent with the hypothesis that song repertoires function to signal the status of the singer.
Little is known about how vocal mimicry affects the behaviour of members of other species. Such effects might, however, be especially likely in mixed-species flocks in which birds of some species directly benefit from the behaviour of members of other species. In mixed-species flocks in Sri Lanka, the greater racket-tailed drongo, Dicrurus paradiseus, mimics the songs and contact calls of other flock participants. We hypothesized that this mimicry attracts other species, as drongos are well known to increase their foraging efficiency in association with other species. Consistent with the predictions of this hypothesis, we recorded the most mimicked vocalizations during the rare occasions in which drongos were outside of flocks. In addition, we performed a playback experiment, which showed that taped drongo vocalizations that included song mimicry were more than twice as attractive to birds of other species as were taped vocalizations that lacked mimicry. We suggest that mimicry is a way in which drongos manage the behaviour of flockmates in what appears to be overall a mutualistic relationship.
The sexual responsiveness of female canaries, Serinus canaria, to six different types of male song phrases extracted from natural song was tested. Copulation solicitation displays were used as an index of female sexual response. Playbacks were performed several days before and during egg laying (a period of natural sexual responsiveness of the females to song). Female canaries were especially responsive to particular short phrases whose essential features were abrupt frequency fall and short silences. This differential responsiveness occurred whatever the serial position (beginning, middle or end) of the phrase in the song and its serial relationship to other different conspecific phrases as well as the general song context (conspecific or heterospecific phrases). Influences such as early experience or ‘sensory bias’ that may lead to a particular sexual sensitivity of female canaries to these types of song phrases are discussed.
Starlings imitate a variety of avian species and have a repertoire of about 15-20 distinct imitations. They also imitate a few sounds other than those of wild birds. The calls of abundant species, calls that are simple in frequency structure and calls that show little amplitude modulation are preferentially imitated. There are local dialects of mimicked sounds. These results are discussed in relation to possible functional explanations of vocal mimicry. Explanations which involve the deceit of other birds are rejected. It is concluded that the understanding of vocal mimicry is probably not distinct from the understanding of the rest of the song.
What are the relative roles of imitation, improvisation and invention in the development of large song repertoires in species of the songbird family Mimidae? This question was addressed in a laboratory study of the vocal development of young grey catbirds, Dumetella carolinensiscollected from western Massachusetts. Two groups heard a repeated 10-s, tape-tutored segment of catbird song, two other groups heard a repeated 16-min segment and a fifth group heard no tape-tutored songs. One male selected for study from each group developed a large repertoire of seemingly normal songs, and wild males responded strongly to songs of the male that had heard no tape-tutored song. Relying little on precise imitation and largely on improvising or inventing, each male developed a highly unique repertoire. A geographical survey of catbird song revealed little to no evidence of song sharing or microgeographical variation, which is consistent with the idea that imitation plays a relatively minor role in song development. Perhaps simultaneous selection for large repertoires and reduced geographical variation has led to such an emphasis on song individuality and non-imitative developmental processes.
Brood-parasitic village indigobirds, Vidua chalybeata, were bred in captivity and foster-reared by their normal host, red-billed firefinch, Lagonosticta senegala, or by an experimental foster species, Bengalese finch, Lonchura striata. Male indigobirds reared by Bengalese finches developed the songs of Bengalese finches, and males reared by firefinches developed songs of firefinches. Males copied their foster father only when they had lived with him long after independence (45 days post-fledging), while males separated normally at independence (22-24 days post-fledging) copied songs of other individuals and not songs of their foster father. Males reared by Bengalese finches showed no preference to learn firefinch song over songs of the experimental foster species or other control finch species even when they had lived with firefinches as companions from the time of fledging to independence. Males copied several song themes, acquired the same number of mimicry songs, and acquired their songs at the same age, whether reared by Bengalese finches or by firefinches. When they lived with other indigobirds, the male indigobirds copied mimicry songs of male indigobirds that mimicked the same foster species. We predicted mimicry-song specificity and repertoire size in experimental indigobirds from a hypothesis of an early developmental period when young indigobirds focus their attention on their foster parents, and a later period when they direct their attention to other birds with similar songs. The predictions, based on field observations of wild birds, were that (1) males reared by a novel foster species other than the normal host would learn the song of that foster species, and (2) males that left their foster parents at the normal time of independence would copy the songs of other individuals, including other adult indigobirds that mimicked the same foster species. Begging calls of young indigobirds did not mimic the calls of young firefinches. Indigobirds reared alone, or with young of the normal host or of the experimental foster species, all developed begging calls in adult song that resembled their own begging as nestlings and fledglings, and only males that heard other adult indigobirds with firefinch-mimicry begging developed firefinch begging in their song. The incorporation of the innate begging calls as well as the learned begging calls into adult song, and the modification of the song themes of their individual song models, suggest that song development involves processes in addition to copying the songs of their own foster species and of older adult male indigobirds with songs like their own foster parents. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.
Males of certain hummingbird species such as Anna's hummingbirds (Calypte anna) learn their song during postnatal development. Here we report that male Anna's hummingbirds and male Amazilia hummingbirds (Amazilia amazilia), two singing hummingbird species, possess forebrain areas that are similar in morphological appearance, location, and connectivity to the song control areas RA (nucleus robustus archistriatalis), HVC (nucleus hyperstriatalis ventrale, pars caudale, or higher vocal center), and LMAN (lateral part of nucleus mangnocellularis anterioris) of oscine passerines (songbirds). The vocal control areas of songbirds are further defined by the expression of androgen receptors. Similarly, the singing hummingbird species express androgen receptors in the LMAN-like area and in the HVC-like area. The hummingbird RA projects to the medullary syringeal motonucleus nXIIts (nucleus hypoglossus pars tracheosyringealis) and the respiratory premotonucleus RAm (nucleus retroambigualis). The HVC-, RA-, and LMAN-like areas are rudimentary in adult male ruby-throated hummingbirds (Archilochus colubris) and Allen's hummingbirds (Selasphorus sasin) and not distinguishable in female hummingbirds, none of which sing. Vocal-area-like forebrain areas (delineated by the cytoarchitecture or androgen receptor expression) were not found in vocal nonlearning swifts and suboscines, the taxonomic sister groups of hummingbirds and songbirds, respectively.