JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected].
Song is a fundamental component of territory defense and mate attraction in birds, and androgens ... more Song is a fundamental component of territory defense and mate attraction in birds, and androgens (like testosterone) are known to play a key role in controlling it. However, little is known about how differences in testosterone levels between males translate into inter-individual song variation. Indeed, testosterone could affect both the motivation to sing and the structure of song itself. Here,
Why some bird species have evolved elaborate song repertoires has puzzled biologists for a long t... more Why some bird species have evolved elaborate song repertoires has puzzled biologists for a long time. According to the antiexhaustion hypothesis avian song type repertoires have evolved because switching between different songs, involving different patterns of muscle contractions, causes less exhaustion in the singer and thus allows a higher song rate to be maintained. Although it is a classic explanation referred to in many textbooks, this hypothesis is still the subject of debate. We investigated the antiexhaustion idea in the chaffinch, Fringilla coelebs, a species in which males may have only one song type or a repertoire of up to six types. We analysed the song delivery rates of 101 male chaffinches, taking into account various seasonal, ecological and social variables. We found that males with a repertoire of several song types did not sing at a higher rate than males with only one song type, even though single song type males produced longer songs on average. Also, repertoire birds singing at high rates did not switch song types more often. These findings indicate that song type switching is not necessary for the maintenance of high song rates in this species. We conclude that preventing motor fatigue was not important in the evolution of chaffinch song type repertoires. Thus other factors, such as direct sexual selection of repertoire size or the use of song type repertoires for vocal interactions, are much more likely to explain why many bird species have evolved a repertoire of several song types. Ó
Keywords: female song preference mate choice operant conditioning signal degradation song amplitu... more Keywords: female song preference mate choice operant conditioning signal degradation song amplitude Taeniopygia guttata zebra finch
In cities with intense low-frequency traffic noise, birds have been observed to sing louder and a... more In cities with intense low-frequency traffic noise, birds have been observed to sing louder and at a higher pitch. Several studies argue that higher song pitch is an adaptation to reduce masking from noise, and it has even been suggested that the song divergence between urban and nonurban songs might lead to reproductive isolation. Here we present models of signal transmission to compare the benefits of raised song amplitude and song pitch in terms of sound transmission. We chose two bird species that sing with higher pitch in urban areas, the great tit (Parus major) and the blackbird (Turdus merula). For both species, we calculated communication distances in response to different levels of urban noise and in their natural forest habitats. We found that an increase in vocal pitch increased communication distance only marginally. In contrast, vocal amplitude adjustments had a strong and significantly larger effect. Our results indicate that frequency changes of urban songs are not very effective in mitigating masking from traffic noise. Increased song pitch might not be an adaptation to reduce signal masking but a physiological side effect of singing at high amplitudes or an epiphenomenon of urbanization that is not related to signal transmission.
When animals colonize cities they often have to adapt their physiology, life history and behaviou... more When animals colonize cities they often have to adapt their physiology, life history and behaviour to the novel environment. Songbirds rely on acoustic communication for reproduction, and recent studies indicate that songs vary between urban and nonurban habitats. In cities, birds sing louder or use higher frequencies compared to their conspecifics in forests. These habitat-specific differences in song have been interpreted as an adaptation of the city birds to mitigate acoustic masking by low-frequency traffic noise. We compared the songs of blackbirds, Turdus merula, from the city centre of Vienna and the Vienna Woods and found that forest birds sang at lower frequencies and with longer intervals between songs. This difference in song pitch might reflect an adaptation to urban ambient noise. However, the song divergence could also be the result of more intense vocal interaction in the more densely populated city areas or a side-effect of physiological adaptation to urban habitats. We emphasize the need for experimental studies in blackbirds, but also in other species, to clarify a possible causal link between urban acoustics and song characteristics of city birds.
Acoustic signals attenuate with the distance over which they travel, but a vocalizing animal migh... more Acoustic signals attenuate with the distance over which they travel, but a vocalizing animal might maintain signal transmission by increasing vocal amplitude when addressing a distant receiver. Such behaviour is well known in humans as speakers vary vocal amplitude with changing distance from an audience, a phenomenon that has been interpreted as resulting from our higher cognitive abilities. However, whether nonhuman animals are capable of this form of vocal adjustment appears to be unknown. We investigated whether birds are also able to regulate the amplitude of their vocal signals depending on receiver distance. Male zebra finches, Taeniopygia guttata, increased their song amplitude with increasing distance to addressed females, indicating that songbirds, like humans, respond to differences in communication distance and that they adjust vocal amplitude accordingly. Our findings show that animal communication is flexible in a previously unsuspected way, and that human speech and bird song share a basic mechanism for ensuring signal transmission. We suggest that this behaviour can be accounted for by simple proximate mechanisms rather than by the cognitive abilities that have been thought necessary in humans.
Collective signalling in animals has fascinated biologists for a long time. A recent study on Aus... more Collective signalling in animals has fascinated biologists for a long time. A recent study on Australian songbirds sheds new light on the function of highly coordinated avian duets.
Several recent studies have tested the hypothesis that song quality in adult birds may reflect ea... more Several recent studies have tested the hypothesis that song quality in adult birds may reflect early developmental conditions, specifically nutritional stress during the nestling period. Whilst all of these earlier studies found apparent links between early nutritional stress and song quality, their results disagree as to which aspects of song learning or production were affected. In this study, we attempted
... Similarly, blue monkeys (Cercopithecus mitis) and pygmy marmosets (Cebuella pygmaea) produce ... more ... Similarly, blue monkeys (Cercopithecus mitis) and pygmy marmosets (Cebuella pygmaea) produce calls with dominant frequencies coinciding with typical low‐amplitude regions in the ... Interestingly enough, the simple acoustic structure of large‐billed leaf‐warbler songs is ...
Primates acquire knowledge about relationships of third parties and group structure by monitoring... more Primates acquire knowledge about relationships of third parties and group structure by monitoring their conspecifics. We show that Barbary macaques (Macaca sylvanus) utter specific vocalizations while monitoring interactions of other group members. As they did not direct other behaviours to the interacting group members, we provisionally termed these vocalizations 'vocal comments'. We investigated the acoustic properties of these comments and the social contexts in which they occurred. Most adult males and females of two studied groups produced low-amplitude calls when observing close contact interactions of other group members. The acoustic features of these calls varied with characteristics of the commented situation. Our results suggest that such calls might not be directed towards the agents of the commented situation, but towards other group members. The vocal comments may signal the caller's awareness of the observed interaction and possibly attract the attention of others to the situation.
Several recent studies have tested the hypothesis that song quality in adult birds may reflect ea... more Several recent studies have tested the hypothesis that song quality in adult birds may reflect early developmental conditions, specifically nutritional stress during the nestling period. Whilst all of these earlier studies found apparent links between early nutritional stress and song quality, their results disagree as to which aspects of song learning or production were affected. In this study, we attempted to reconcile these apparently inconsistent results. Our study also provides the first assessment of song amplitude in relation to early developmental stress and as a potential cue to male quality. We used an experimental manipulation in which the seeds on which the birds were reared were mixed with husks, making them more difficult for the parents to obtain. Compared with controls, such chicks were lighter at fledging; they were thereafter placed on a normal diet and had caught up by 100 days. We show that nutritional stress during the first 30 days of life reduced the birds' accuracy of song syntax learning, resulting in poorer copies of tutor songs. Our experimental manipulations did not lead to significant changes in song amplitude, song duration or repertoire size. Thus, individual differences observed in song performance features probably reflect differences in current condition or motivation rather than past condition.
Many animal signals are performed in a highly redundant manner as in some bird species where male... more Many animal signals are performed in a highly redundant manner as in some bird species where males sing several renditions of one song type before switching to another. However, differences in signal redundancy between contexts and between individuals are only poorly understood. We found that chaffinches (Fringilla coelebs) in noisier areas (i.e., close to waterfalls and torrents) sang longer bouts of the same song type before switching to a new type, suggesting that they use increased serial redundancy to get the message across in noisy conditions. This is the first evidence of a noise-dependent adjustment of signal redundancy in a songbird. In addition, we found that song types with faster trills were sung in shorter bouts suggesting that the performance of highly redundant song series is probably limited by motor constraints. Thus, in noisy environments, serial redundancy in bird song may reflect a trade-off between successful signal transmission and preventing motor fatigue.
Keywords: acoustic communication Acrocephalus schoenobaenus birdsong directional communication se... more Keywords: acoustic communication Acrocephalus schoenobaenus birdsong directional communication sedge warbler sound radiation vocal directionality
Why some bird species have evolved elaborate song repertoires has puzzled biologists for a long t... more Why some bird species have evolved elaborate song repertoires has puzzled biologists for a long time. According to the antiexhaustion hypothesis avian song type repertoires have evolved because switching between different songs, involving different patterns of muscle contractions, causes less exhaustion in the singer and thus allows a higher song rate to be maintained. Although it is a classic explanation referred to in many textbooks, this hypothesis is still the subject of debate. We investigated the antiexhaustion idea in the chaffinch, Fringilla coelebs, a species in which males may have only one song type or a repertoire of up to six types. We analysed the song delivery rates of 101 male chaffinches, taking into account various seasonal, ecological and social variables. We found that males with a repertoire of several song types did not sing at a higher rate than males with only one song type, even though single song type males produced longer songs on average. Also, repertoire birds singing at high rates did not switch song types more often. These findings indicate that song type switching is not necessary for the maintenance of high song rates in this species. We conclude that preventing motor fatigue was not important in the evolution of chaffinch song type repertoires. Thus other factors, such as direct sexual selection of repertoire size or the use of song type repertoires for vocal interactions, are much more likely to explain why many bird species have evolved a repertoire of several song types. Ó
Keywords: acoustic adaptation acoustic communication ambient noise blackbird birdsong Turdus meru... more Keywords: acoustic adaptation acoustic communication ambient noise blackbird birdsong Turdus merula urban ecology urban habitat When animals colonize cities they often have to adapt their physiology, life history and behaviour to the novel environment. Songbirds rely on acoustic communication for reproduction, and recent studies indicate that songs vary between urban and nonurban habitats. In cities, birds sing louder or use higher frequencies compared to their conspecifics in forests. These habitat-specific differences in song have been interpreted as an adaptation of the city birds to mitigate acoustic masking by low-frequency traffic noise. We compared the songs of blackbirds, Turdus merula, from the city centre of Vienna and the Vienna Woods and found that forest birds sang at lower frequencies and with longer intervals between songs. This difference in song pitch might reflect an adaptation to urban ambient noise. However, the song divergence could also be the result of more intense vocal interaction in the more densely populated city areas or a side-effect of physiological adaptation to urban habitats. We emphasize the need for experimental studies in blackbirds, but also in other species, to clarify a possible causal link between urban acoustics and song characteristics of city birds. Ó
The evolution of mating signals is closely linked to sexual selection. Acoustic ornaments are oft... more The evolution of mating signals is closely linked to sexual selection. Acoustic ornaments are often used as secondary sexual traits that signal the quality of the signaller. Here we show that song performance reflects age and reproductive success in the rock sparrow (Petronia petronia). In an Alpine population in south-east France, we recorded the songs of males and assessed their genetic breeding success by microsatellite analysis. In addition to temporal and spectral song features, we also analysed for the first time whether the sound pressure level of bird song reflects reproductive success. Males with higher breeding success sang at a lower rate and with a higher maximum frequency. We found also that older males gained more extra-pair young and had a higher overall breeding success, although they also differed almost significantly by having a higher loss of paternity in their own nests. Older males could be distinguished from yearlings by singing at lower rate and higher amplitudes. Our findings suggest that song rate may be used as a signal of age and together with song pitch as a signal of reproductive success in this species. Alternatively, younger and less successful males might try to compensate their inferior status by increased song rates and lower pitch. Independent of age and quality, high-amplitude songs correlated with paternity loss in the own nest, suggesting that in this species song amplitude is not an indicator of male quality but high-intensity songs may be rather a response to unfaithful social mates.
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected].
Song is a fundamental component of territory defense and mate attraction in birds, and androgens ... more Song is a fundamental component of territory defense and mate attraction in birds, and androgens (like testosterone) are known to play a key role in controlling it. However, little is known about how differences in testosterone levels between males translate into inter-individual song variation. Indeed, testosterone could affect both the motivation to sing and the structure of song itself. Here,
Why some bird species have evolved elaborate song repertoires has puzzled biologists for a long t... more Why some bird species have evolved elaborate song repertoires has puzzled biologists for a long time. According to the antiexhaustion hypothesis avian song type repertoires have evolved because switching between different songs, involving different patterns of muscle contractions, causes less exhaustion in the singer and thus allows a higher song rate to be maintained. Although it is a classic explanation referred to in many textbooks, this hypothesis is still the subject of debate. We investigated the antiexhaustion idea in the chaffinch, Fringilla coelebs, a species in which males may have only one song type or a repertoire of up to six types. We analysed the song delivery rates of 101 male chaffinches, taking into account various seasonal, ecological and social variables. We found that males with a repertoire of several song types did not sing at a higher rate than males with only one song type, even though single song type males produced longer songs on average. Also, repertoire birds singing at high rates did not switch song types more often. These findings indicate that song type switching is not necessary for the maintenance of high song rates in this species. We conclude that preventing motor fatigue was not important in the evolution of chaffinch song type repertoires. Thus other factors, such as direct sexual selection of repertoire size or the use of song type repertoires for vocal interactions, are much more likely to explain why many bird species have evolved a repertoire of several song types. Ó
Keywords: female song preference mate choice operant conditioning signal degradation song amplitu... more Keywords: female song preference mate choice operant conditioning signal degradation song amplitude Taeniopygia guttata zebra finch
In cities with intense low-frequency traffic noise, birds have been observed to sing louder and a... more In cities with intense low-frequency traffic noise, birds have been observed to sing louder and at a higher pitch. Several studies argue that higher song pitch is an adaptation to reduce masking from noise, and it has even been suggested that the song divergence between urban and nonurban songs might lead to reproductive isolation. Here we present models of signal transmission to compare the benefits of raised song amplitude and song pitch in terms of sound transmission. We chose two bird species that sing with higher pitch in urban areas, the great tit (Parus major) and the blackbird (Turdus merula). For both species, we calculated communication distances in response to different levels of urban noise and in their natural forest habitats. We found that an increase in vocal pitch increased communication distance only marginally. In contrast, vocal amplitude adjustments had a strong and significantly larger effect. Our results indicate that frequency changes of urban songs are not very effective in mitigating masking from traffic noise. Increased song pitch might not be an adaptation to reduce signal masking but a physiological side effect of singing at high amplitudes or an epiphenomenon of urbanization that is not related to signal transmission.
When animals colonize cities they often have to adapt their physiology, life history and behaviou... more When animals colonize cities they often have to adapt their physiology, life history and behaviour to the novel environment. Songbirds rely on acoustic communication for reproduction, and recent studies indicate that songs vary between urban and nonurban habitats. In cities, birds sing louder or use higher frequencies compared to their conspecifics in forests. These habitat-specific differences in song have been interpreted as an adaptation of the city birds to mitigate acoustic masking by low-frequency traffic noise. We compared the songs of blackbirds, Turdus merula, from the city centre of Vienna and the Vienna Woods and found that forest birds sang at lower frequencies and with longer intervals between songs. This difference in song pitch might reflect an adaptation to urban ambient noise. However, the song divergence could also be the result of more intense vocal interaction in the more densely populated city areas or a side-effect of physiological adaptation to urban habitats. We emphasize the need for experimental studies in blackbirds, but also in other species, to clarify a possible causal link between urban acoustics and song characteristics of city birds.
Acoustic signals attenuate with the distance over which they travel, but a vocalizing animal migh... more Acoustic signals attenuate with the distance over which they travel, but a vocalizing animal might maintain signal transmission by increasing vocal amplitude when addressing a distant receiver. Such behaviour is well known in humans as speakers vary vocal amplitude with changing distance from an audience, a phenomenon that has been interpreted as resulting from our higher cognitive abilities. However, whether nonhuman animals are capable of this form of vocal adjustment appears to be unknown. We investigated whether birds are also able to regulate the amplitude of their vocal signals depending on receiver distance. Male zebra finches, Taeniopygia guttata, increased their song amplitude with increasing distance to addressed females, indicating that songbirds, like humans, respond to differences in communication distance and that they adjust vocal amplitude accordingly. Our findings show that animal communication is flexible in a previously unsuspected way, and that human speech and bird song share a basic mechanism for ensuring signal transmission. We suggest that this behaviour can be accounted for by simple proximate mechanisms rather than by the cognitive abilities that have been thought necessary in humans.
Collective signalling in animals has fascinated biologists for a long time. A recent study on Aus... more Collective signalling in animals has fascinated biologists for a long time. A recent study on Australian songbirds sheds new light on the function of highly coordinated avian duets.
Several recent studies have tested the hypothesis that song quality in adult birds may reflect ea... more Several recent studies have tested the hypothesis that song quality in adult birds may reflect early developmental conditions, specifically nutritional stress during the nestling period. Whilst all of these earlier studies found apparent links between early nutritional stress and song quality, their results disagree as to which aspects of song learning or production were affected. In this study, we attempted
... Similarly, blue monkeys (Cercopithecus mitis) and pygmy marmosets (Cebuella pygmaea) produce ... more ... Similarly, blue monkeys (Cercopithecus mitis) and pygmy marmosets (Cebuella pygmaea) produce calls with dominant frequencies coinciding with typical low‐amplitude regions in the ... Interestingly enough, the simple acoustic structure of large‐billed leaf‐warbler songs is ...
Primates acquire knowledge about relationships of third parties and group structure by monitoring... more Primates acquire knowledge about relationships of third parties and group structure by monitoring their conspecifics. We show that Barbary macaques (Macaca sylvanus) utter specific vocalizations while monitoring interactions of other group members. As they did not direct other behaviours to the interacting group members, we provisionally termed these vocalizations 'vocal comments'. We investigated the acoustic properties of these comments and the social contexts in which they occurred. Most adult males and females of two studied groups produced low-amplitude calls when observing close contact interactions of other group members. The acoustic features of these calls varied with characteristics of the commented situation. Our results suggest that such calls might not be directed towards the agents of the commented situation, but towards other group members. The vocal comments may signal the caller's awareness of the observed interaction and possibly attract the attention of others to the situation.
Several recent studies have tested the hypothesis that song quality in adult birds may reflect ea... more Several recent studies have tested the hypothesis that song quality in adult birds may reflect early developmental conditions, specifically nutritional stress during the nestling period. Whilst all of these earlier studies found apparent links between early nutritional stress and song quality, their results disagree as to which aspects of song learning or production were affected. In this study, we attempted to reconcile these apparently inconsistent results. Our study also provides the first assessment of song amplitude in relation to early developmental stress and as a potential cue to male quality. We used an experimental manipulation in which the seeds on which the birds were reared were mixed with husks, making them more difficult for the parents to obtain. Compared with controls, such chicks were lighter at fledging; they were thereafter placed on a normal diet and had caught up by 100 days. We show that nutritional stress during the first 30 days of life reduced the birds' accuracy of song syntax learning, resulting in poorer copies of tutor songs. Our experimental manipulations did not lead to significant changes in song amplitude, song duration or repertoire size. Thus, individual differences observed in song performance features probably reflect differences in current condition or motivation rather than past condition.
Many animal signals are performed in a highly redundant manner as in some bird species where male... more Many animal signals are performed in a highly redundant manner as in some bird species where males sing several renditions of one song type before switching to another. However, differences in signal redundancy between contexts and between individuals are only poorly understood. We found that chaffinches (Fringilla coelebs) in noisier areas (i.e., close to waterfalls and torrents) sang longer bouts of the same song type before switching to a new type, suggesting that they use increased serial redundancy to get the message across in noisy conditions. This is the first evidence of a noise-dependent adjustment of signal redundancy in a songbird. In addition, we found that song types with faster trills were sung in shorter bouts suggesting that the performance of highly redundant song series is probably limited by motor constraints. Thus, in noisy environments, serial redundancy in bird song may reflect a trade-off between successful signal transmission and preventing motor fatigue.
Keywords: acoustic communication Acrocephalus schoenobaenus birdsong directional communication se... more Keywords: acoustic communication Acrocephalus schoenobaenus birdsong directional communication sedge warbler sound radiation vocal directionality
Why some bird species have evolved elaborate song repertoires has puzzled biologists for a long t... more Why some bird species have evolved elaborate song repertoires has puzzled biologists for a long time. According to the antiexhaustion hypothesis avian song type repertoires have evolved because switching between different songs, involving different patterns of muscle contractions, causes less exhaustion in the singer and thus allows a higher song rate to be maintained. Although it is a classic explanation referred to in many textbooks, this hypothesis is still the subject of debate. We investigated the antiexhaustion idea in the chaffinch, Fringilla coelebs, a species in which males may have only one song type or a repertoire of up to six types. We analysed the song delivery rates of 101 male chaffinches, taking into account various seasonal, ecological and social variables. We found that males with a repertoire of several song types did not sing at a higher rate than males with only one song type, even though single song type males produced longer songs on average. Also, repertoire birds singing at high rates did not switch song types more often. These findings indicate that song type switching is not necessary for the maintenance of high song rates in this species. We conclude that preventing motor fatigue was not important in the evolution of chaffinch song type repertoires. Thus other factors, such as direct sexual selection of repertoire size or the use of song type repertoires for vocal interactions, are much more likely to explain why many bird species have evolved a repertoire of several song types. Ó
Keywords: acoustic adaptation acoustic communication ambient noise blackbird birdsong Turdus meru... more Keywords: acoustic adaptation acoustic communication ambient noise blackbird birdsong Turdus merula urban ecology urban habitat When animals colonize cities they often have to adapt their physiology, life history and behaviour to the novel environment. Songbirds rely on acoustic communication for reproduction, and recent studies indicate that songs vary between urban and nonurban habitats. In cities, birds sing louder or use higher frequencies compared to their conspecifics in forests. These habitat-specific differences in song have been interpreted as an adaptation of the city birds to mitigate acoustic masking by low-frequency traffic noise. We compared the songs of blackbirds, Turdus merula, from the city centre of Vienna and the Vienna Woods and found that forest birds sang at lower frequencies and with longer intervals between songs. This difference in song pitch might reflect an adaptation to urban ambient noise. However, the song divergence could also be the result of more intense vocal interaction in the more densely populated city areas or a side-effect of physiological adaptation to urban habitats. We emphasize the need for experimental studies in blackbirds, but also in other species, to clarify a possible causal link between urban acoustics and song characteristics of city birds. Ó
The evolution of mating signals is closely linked to sexual selection. Acoustic ornaments are oft... more The evolution of mating signals is closely linked to sexual selection. Acoustic ornaments are often used as secondary sexual traits that signal the quality of the signaller. Here we show that song performance reflects age and reproductive success in the rock sparrow (Petronia petronia). In an Alpine population in south-east France, we recorded the songs of males and assessed their genetic breeding success by microsatellite analysis. In addition to temporal and spectral song features, we also analysed for the first time whether the sound pressure level of bird song reflects reproductive success. Males with higher breeding success sang at a lower rate and with a higher maximum frequency. We found also that older males gained more extra-pair young and had a higher overall breeding success, although they also differed almost significantly by having a higher loss of paternity in their own nests. Older males could be distinguished from yearlings by singing at lower rate and higher amplitudes. Our findings suggest that song rate may be used as a signal of age and together with song pitch as a signal of reproductive success in this species. Alternatively, younger and less successful males might try to compensate their inferior status by increased song rates and lower pitch. Independent of age and quality, high-amplitude songs correlated with paternity loss in the own nest, suggesting that in this species song amplitude is not an indicator of male quality but high-intensity songs may be rather a response to unfaithful social mates.
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