Song Type Matching Research Articles

Song type and song type matching are important for joint territorial defense in a duetting songbird.

Birds have a diverse acoustic communication system, with species-specific repertoires facilitating more complex behaviors in terms of both within- and between-pair communications. Certain song types are produced for specific functions, such as aggressive encounters. In addition, song matching behaviors, whereby neighboring individuals match song types, can be used in aggressive interactions as a sophisticated acoustic behavior. In this study, we examined the functions of song types, in a duet context, of male yellow-breasted boubous (Laniarius atroflavus), an Afromontane bush-shrike with a vocal sexual dimorphism. We aimed at assessing whether, structurally, certain song types elicited a heightened reaction than others and also whether song matching affected response behavior. A dual speaker playback procedure was performed for 18 pairs of boubous, each pair being exposed to duets with three different male song types. We found differences in response toward the different duet types but these differences resulted from the amount at which males matched different song types. Pairs responded stronger when a focal male matched the playback type, and matching was significantly more often found in cases where the rarest type of male song was used. We found no sex differences in terms of response strength to playback type. Our results indicate a two-level way of coding aggression toward intruding pairs. The yellow-breasted boubous utilize their repertoires, linking matching with structure in order to show aggression in terms of territory defense and sexual conflict. This study also confirms joint territorial defense as a main function of duets in this species.

Constraints on song type matching in a songbird

In an eastern population of song sparrows (Melospiza melodia), song type matching occurs at above chance levels but does not signal aggressiveness. One explanation for the apparent ineffectiveness of matching as a signal is that the occurrence of matching is constrained by internal rules for ordering the production of song types. This constraint hypothesis is tested here in an experiment in which the singing of territorial male song sparrows is monitored in the field in real time, and subjects are confronted with playback of one of their song types either immediately after switching away from that type (short-delay) or after having cycled through much of their repertoire since last singing that type (long-delay). Matching was not significantly more likely in the long-delay treatment than in the short-delay treatment. The probability of matching did, however, depend significantly on prior bout length: the longer was a singer’s last bout of a song type, the less likely the singer was to match it. There was also a suggestive effect of frequency of usage: males were more likely to match a song type the more frequently they normally sang that type, though this result was not significant after correcting for multiple comparisons. Thus, internal rules on how songs are sequenced exert constraints on the occurrence of song type matching, and such constraints can help to explain the apparent ineffectiveness of matching as a signal in this study population. Research on song type matching in songbirds has largely focused on the signal function of matching, especially on the hypothesis that matching serves as an aggressive signal directed at the matched individual. In some songbirds, however, such as our study population of eastern song sparrows, predictions of the aggressive signaling hypothesis are not supported. Here, we show that the probability that song sparrows match song playback is strongly influenced by internal rules governing the sequencing of song type production. Specifically, the probability that song sparrows will match a particular song type is inversely related to the length of their prior bout of that song type. This result demonstrates how internal syntactical rules governing song type sequencing can constrain the signal function of song type matching.

Song type matching and vocal performance in territorial signalling by male swamp sparrows

In songbird species with repertoires of multiple songs, individuals in territorial interactions can engage in song type matching, in which one bird responds to another using the same song type. Song type matching is thought to be associated with aggressive intent, although empirical support for this hypothesis is mixed. Here we test the alternative hypothesis that males selectively use song type matching, depending on singing ability, to optimize their relative performance in a communication network. We recorded the responses of male swamp sparrows, Melospiza georgiana, to playback trials in which they heard stimulus songs of higher or lower vocal performance relative to their own version of those songs. We predicted that, if males use song type matching to influence the perceptions of conspecifics outside the interacting dyad, males would (1) match stimulus songs that they themselves could perform better and (2) respond with a different song type to stimulus songs that they could not perform as well. We found that males song-type matched more often than expected by chance across trials, but contrary to our expectations, they were at least as likely to match to playback of higher-performance songs as to playback of lower-performance songs. As in previous studies, we also found that males sang with higher vocal performance in response to playback than when singing spontaneously, and that they did not preferentially respond with their highest-performance song type as a countersinging strategy. Our results support the idea that in swamp sparrows, song type matching functions primarily within the dyad rather than to broadcast superior performance ability to other conspecifics in the communication network.

The role of signature whistle matching in bottlenose dolphins, Tursiops truncatus

The addressing of individuals with learned signals is inherent to human social interactions. It allows individuals to solicit the attention of a particular social companion or to direct information towards an intended recipient. The ability to address individual conspecifics with learned signals is not limited to humans, however. In songbirds, the selective addressing of individuals is facilitated by song type matching but is very much a signal of aggressive intent. The matching of learned signals is also observed in bottlenose dolphins, which will match one another's highly individualized signature whistle. Copying in dolphins occurs between close associates, which suggests that it is an affiliative signal. It could, however, also serve to manage aggression. We investigated the valence of signature whistle matching by performing interactive playback experiments. We waited until an animal produced its signature whistle and then either played back a synthetic version of its own whistle (match) or a different signature whistle (control). A total of 110 playback experiments were conducted with seven different animals from two managed groups of dolphins. The responses to the playback treatments were significantly different. Animals produced a consistent vocal response to being vocally matched, by returning the match, with no associated signal of aggression and did not respond to control playbacks in the same way. There was also an optimum time interval (<1 s) in which a match was most successful in eliciting a vocal response. Our results show that signature whistle matching is an affiliative signal that allows bottlenose dolphins to address social companions. Furthermore, these matching exchanges are driven by temporal associations, which appear to be essential in allowing animals to direct signals to particular individuals in large communication networks.

Singing onstage: female and male common nightingales eavesdrop on song type matching

In bird communication, listening individuals may obtain information on the quality and motivation of a male not only from solo-singing, but also from song interactions and listeners base their future decisions in territorial and mating contexts on such public information. Eavesdropping on male interactions may thus have a strong influence on sexual selection. In singing interactions, temporal coordination (e.g. overlapping vs. alternating) of two singers as well as structural interaction patterns (e.g. song type matching or repertoire matching) have been described, but the latter is far less studied. By conducting dual-speaker playback experiments with common nightingales Luscinia megarhynchos, we simulated an interaction where one singer was repeatedly song–type matching his counterpart. Playbacks were broadcast to male and female nightingales, and their approach behaviour and singing responses (in the case of male focals) were analysed. We found that both, males and females, spent more time with the matched bird, whereas males additionally sang more songs towards the matching bird. This can be taken as strong hint that eavesdropping occurs in nightingale communication and that listening to male vocal contests might be an important strategy for both sexes to adjust their behavioural output. With regard to the function of song matching, we assume that song-matching is not an aggressive signal per se in nightingales. We rather conclude that vocal leaders within an interaction, here the matched bird, may elicit stronger responses in conspecifics than vocal followers, here the matching bird.

A test of a hierarchical signalling model in song sparrows

Hierarchical signalling may be a common adaptation for aggressive signalling. In this strategy an animal progresses through a series of discretely different signals of escalating level of threat before eventually proceeding to physical aggression. A model of such hierarchical aggressive signalling has been proposed for song sparrows, Melospiza melodia , in which a core part of the sequence is: song type match → soft song → attack. The model predicts that song type matching is a strong predictor of soft song, but only a weak predictor of attack. We used a two-part playback design to test these predictions, with an initial edge playback from just off the subject's territory using a song type that the subject could match, followed by a centre playback from a speaker placed well within the territory. Each male was tested twice with this design. We found that matching the edge playback did not predict soft song production at the centre. A second strong threat, wing waving, was actually negatively associated with matching. Matching the edge playback also was not associated with physical measures of aggression such as approach and latency to approach. Thus, this particular model of hierarchical aggressive signalling was not supported for our study population. Song type matching in our study population may have some function not associated with aggressive signalling to the matched individual, or no function at all.

Song type matching is an honest early threat signal in a hierarchical animal communication system

Aggressive encounters between animals often involve significant amounts of signalling before or in lieu of physical fights. When, as is often the case, these apparent threat signals are neither inherently costly nor inherently indicative of fighting ability, we should ask whether they are in fact honest signals, i.e. do they predict that escalation is imminent? While signalling theories have indicated that such 'conventional' threat signals can honestly predict escalation, attempts to gather supporting empirical evidence have mostly failed. For example, recent studies in songbirds of song type matching (replying to an opponent's song with the same song type he has just sung) have failed to confirm that it predicts an eventual attack by the signaller. In the present study of song sparrows (Melospiza melodia), we tested the hypothesis that song type matching is an early threat signal in a hierarchical signalling system. We used an improved model-playback design that simulated an escalating intrusion onto the subject's territory: the simulated opponent first sang in hiding from the boundary before moving to the centre of the territory, where he revealed himself and continued to sing. We found that type matching beginning in the boundary phase and continuing into the escalation phase, or beginning immediately after the escalation, reliably predicted both subsequent escalated signalling (soft songs and wing waves) and subsequent attack on the model, supporting the hypothesis that type matching is a reliable early threat signal.

Song-type sharing and matching in a bird with very large song repertoires, the tropical mockingbird

Summary Song-type matching, a behaviour of some songbirds in which one individual replies to another’s song with a matching song type, has been studied primarily in birds that have small to moderately sized song repertoires (<15 song types) and that share only a few song types with neighbours. Few previous studies have examined song-type matching in species with very large song repertoires, in which birds can share larger numbers of songs with neighbours and matching particular song types might be more challenging. Here we describe frequent and rapid song-type matching in a population of tropical mockingbirds, Mimus gilvus. Males had repertoire sizes of about 133 distinct song types on average which were delivered with high versatility. Territorial neighbours shared significantly more song types than did nonneighbours, and neighbouring males matched each other’s songs frequently and often with surprising speed. Overlapping of songs occurred at approximately chance levels. Song-type matching in these birds could indicate more than just aggressive intentions, which is the presumed function of this behaviour in species with smaller repertoires. In tropical mockingbirds, rapidly matching the songs of neighbours could provide information to listeners about a singer’s experience or abilities.

Testing the function of song-matching in birds: responses of eastern male song sparrows Melospiza melodia to partial song-matching

AbstractSong-matching has been hypothesized to be a signal of aggressive intentions whereby matching an opponent signals that the singer is likely to attack. Theory predicts that an aggressive signal should impose a cost that enforces the signal's reliability. A receiver-dependent cost imposed by the matched bird's aggressive retaliation has been proposed for song-matching. We tested for such a cost for partial song-matching in an eastern population of song sparrows where males lack the shared song types necessary for song type matching, but can perform partial song-matching using shared song segments. We tested aggressive response, as measured by average distance to a playback speaker, to partial-matching songs and non-matching songs. We predicted a stronger aggressive response to partial-matching songs, as has been shown for whole song-matching in western song sparrow populations. The birds in our study responded no differently to partial-matching and non-matching songs. Neither the distance to the playback speaker nor singing responses differed between playback treatments. Our results do not support a receiver-dependent cost to partial song-matching, as would be expected if partial-matching is a direct threat. Instead, we suggest that partial song-matching functions as a signal of attention.

The social interaction role of song in song sparrows: implications for signal design

Many territorial songbirds use singing as an interactive social signal to reduce inter-neighbor aggression. Communication theory predicts that territorial songbirds may use repertoires of signals to indicate graded levels of aggressive motivation. This theory is supported in song sparrows, a species that uses several different song-based signals such as song-type matching to escalate or de-escalate aggression during counter-singing interactions. However, birds cannot type match if they do not share the song type their rival is singing, raising the question of how they might signal aggression instead. We present evidence for two alternative signaling strategies that non-sharing neighbors could use to communicate aggressive motivation. In the first case, a bird may ‘similarity match’ a rival’s song by singing the most similar song in his repertoire, even if he cannot type match. Another solution would be for neighbors to agree to treat specific pairs of non-similar types as matches by convention. The conventional match is potentially a new class of signal that territorial neighbors may use along with type and similarity matching to maintain a repertoire of aggressive motivation signals.

Bird song as a signal of aggressive intent

A central question in animal communication research concerns the reliability of animal signals. The question is particularly relevant to aggressive communication, where there often may be advantages to signaling an exaggerated likelihood of attack. We tested whether aggressive signals are indeed reliable signals of attack in song sparrows (Melospiza melodia). We elicited aggressive signaling using a 1-min playback on a male’s territory, recorded the behavior of the male for 5 min, and then gave him the opportunity to attack a taxidermic mount of a song sparrow associated with further playback. Twenty subjects attacked the mount and 75 did not. Distance to the speaker was a significant predictor of attack for both the initial recording period and the 1 min before attack. For the initial recording period, none of the measures of singing behavior that we made was a significant predictor of attack, including song-type matching, type-switching frequency, and song rate. For the 1-min period immediately before attack, only the number of low amplitude “soft songs” was a significant predictor of attack. Although most aggressive signals contained little information on attack likelihood, as some models suggest should be the case, the unreliability of these signals was not caused by convergence of individuals on a single signaling strategy, as those models argue should occur.

Three vocalization types in the blue tit Cyanistes caeruleus: a test of the different signal-value hypothesis

Many songbird species use a repertoire of different song types in close-range interactions. In male blue tits, Cyanistes caeruleus, this includes songs with and without trill as well as scolding-like vocalizations. We here investigate using playback experiments whether these vocalization types are used at different stages during aggressive interactions, which may be reflected in differential responses of receivers. We predict that territory owning receivers will vary their strength of response with the vocalization type of a simulated intruder and that an aggressive territorial response may include song type matching, i.e. the use of the same vocalization type as the intruder. Supporting the different-signal value hypothesis, scolding-like playback elicited a stronger approach response of focal males than playback of songs with or without trill. There was no difference in song rate nor do songs without trill elicit a different strength of response than songs with trill. Males did not differ significantly in the amount of song type matching between the treatments but males that landed on the loudspeaker with playback of either songs without trill or scolding-like vocalizations did not match playback songs at all. This suggests a trade-off between approach and song type matching where song type matching is superfluous during very close approaches. Our results may suggest that in the blue tit threat display may be graded from songs with or without trill to scolding-like vocalizations and eventual attack of an intruder.

Song type matching, song type switching and eavesdropping in male great tits

Eavesdropping involves the extraction of information from signalling interactions by individuals not directly involved. Such behaviour has been conclusively demonstrated by experiments that present songbirds with simulated singing interactions in which the roles of interactants were varied by changing the timing of songs. We examined the phenomenon of song type matching by presenting male great tits, Parus major, with simulated interactions in which one interactant switched song type such that it matched (or not) that sung by the opponent. Subjects responded to simulated intrusion by previously heard interactants by singing significantly shorter songs in response to males that switched (i.e. used two song types), regardless of whether or not matching occurred, compared with those that used one. Subjects also showed a significantly lower level of approach behaviour to males whose opponents had switched song types but not matched. Male great tits are therefore capable of extracting different kinds of information by eavesdropping on interactions between others and using that information when deciding how to respond to subsequent intrusion. These results confirm and expand our knowledge on the potential of eavesdropping to provide accurate information on the likely strengths and weaknesses of potential rivals.

Countersinging as a signal of aggression in a territorial songbird

Neighbouring territorial songbirds often interact through countersinging, where birds sing in response to the singing of neighbours such that their song bouts are temporally related. Complex forms of countersinging such as song type matching or song overlapping appear to be correlated with aggressiveness and readiness to escalate confrontations. Less attention has been paid to the importance of simpler forms of countersinging, where matched song types are not used and where individual songs do not temporally overlap. I examined countersinging behaviour in male Carolina wrens, Thryothorus ludovicianus, which countersing regularly. Why they countersing and how countersinging is perceived by neighbours is unknown. By comparing singing behaviour before and after simulated intrusions, I determined that subjects countersing with their neighbours more readily when highly aroused. Comparing responses to countersinging and noncountersinging playbacks showed that countersinging elicited more aggressive responses than did noncountersinging. Carolina wrens appear to exchange aggressive signals regularly through countersinging. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.

Latent song type memories are accessible through auditory stimulation in a hand-reared songbird

The production of learned vocalizations such as in birdsong is often used to judge whether stimuli had been memorized upon their presentation. However, failures in the imitation of certain song patterns may also reflect impaired development of motor programmes or impaired memory retrieval rather than failures in stimulus memorization during auditory acquisition. To study this issue, we confronted adult hand-reared nightingales, Luscinia megarhynchos, with interactive playback experiments and used vocal matching as a behavioural tool to investigate their song type memories. Vocal matching is a common pattern-specific response that songbirds use in territorial countersinging. We distinguished two forms of pattern-specific matching: (1) song type matching (i.e. a bird replied with the same song type as the stimulus song), and (2) song group matching (i.e. the bird replied with a different song type which was, however, sequentially associated with the playback song presented earlier, i.e. during the tutoring). Some subjects used both song type and song group matching in response to song types they had not imitated from the tutor programme prior to the playback experiments. Our results indicate that nightingales store more song types in their sensory phase than they spontaneously recall from memory as adults. That is, memories of song types that were not performed in overt behaviour could be activated by vocal interactions, here induced by the interactive playback. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

SONG SHARING BY YELLOW WARBLERS DIFFERS BETWEEN TWO MODES OF SINGING: IMPLICATIONS FOR SONG FUNCTION

Abstract I investigated the pattern of song sharing for the two singing modes (Type I and Type II) of Yellow Warblers (Dendroica petechia). There is indirect evidence that males use Type I singing to attract females, and Type II singing to interact with other males, but how males use these singing modes for these functions is unknown. One way in which males might use Type II singing to interact with neighboring males is through the use of “shared songs:” males might preferentially sing songs they share with neighboring males to engage in song type matching or repertoire matching. I tested the prediction that Yellow Warblers should share more of their Type II songs with neighbors compared to non-neighbors, but that there should be no such relationship for Type I songs. I found that males in a Pennsylvania population shared significantly more of their Type II song repertoire with neighbors than with non-neighbors, and that sharing between males declined with distance between their territories. There was no ...

Is song-type matching a conventional signal of aggressive intentions?

Song-type matching is a singing strategy found in some oscine songbirds with repertoires of song types and at least partial sharing of song types between males. Males reply to the song of a rival male by subsequently singing the same song type. For type matching to serve as an effective long-distance threat signal, it must be backed up by some probability of aggressive approach and impose some type of cost on senders that minimizes the temptation to bluff. Western subspecies of the song sparrow exhibit moderate levels of song-type sharing between adjacent males and sometimes type match in response to playback of song types they possess in their repertoires. Interactive playback experiments were used in order to examine the subsequent behaviour of type-matching birds and to quantify the responses of focal birds to type-matching versus non-matching stimuli. Birds that chose to type match the playback of a shared song type subsequently approached the speaker much more aggressively than birds that did not type match. Moreover, birds approached a type-matching stimulus much more aggressively than a non-matching stimulus. These results and consideration of alternatives suggest that type matching in song sparrows is a conventional signal in which honesty is maintained by a receiver retaliation cost against bluffers.

Song-type matching between neighbouring song sparrows

In our study population, neighbouring song sparrows typically share two or more of their 6–10 song types. In an earlier experiment, we found that established neighbours typically reply to playback of neighbour-shared song with a different song they share with that neighbour (‘repertoire matching’), rather than with the same song (‘type matching’) or with a nonshared song. In the present experiment, we considered the hypothesis that type matching is a threat or warning signal (Krebs et al. 1981, Animal Behaviour, 29, 918–923). We tested the specific prediction that a bird is more likely to type-match early in the breeding season when territory boundaries are new and still unstable, and more likely to repertoire-match later in the season, once those boundaries have become well established. Birds were played a shared song of a new neighbour once early (April) and again late (June) in the breeding season. As predicted, early in the season birds usually type-matched the playback (73% of the trials) but late in the season they type-matched only rarely (18%); birds never replied (early or late) with a nonshared song type.

Responses of song sparrows to song-type matching via interactive playback

Responses of song sparrows to song-type matching via interactive playback

Responses of song sparrows to song-type matching via interactive playback

The aggressive and singing responses of ten territorial male song sparrows, Melospiza melodia, to sustained song-type matching via interactive playback were examined. This auditory stimulus, which involves both synchronous switching and song-type matching, was hypothesized to be a strong aggressive threat. Responses were compared to five other trial types in which the switching pattern and song-type similarity were independently varied. The six trial types were organized into a factorial design with three switching levels (no switching, synchronized switching, and rapid unsynchronized switching) and two matching levels (shared song-types and unshared song-types). The aggressive response of the birds, a composite index of the correlated behaviors of singing rate, perch change rate, and time spent close to the speaker, showed significant main effects of both the switching and the matching factors, with no interaction effect. The response was highest for the shared/ unsynchronized switching trial and lowest for the unshared/no switching trial. Since the synchronous switching trials produced aggressive responses intermediate between the no switching and rapid unsynchronized switching trials, our results corroborate earlier studies showing that switching rate, song-type diversity and song similarity are the key determinants of aggressive approach. However, the switching rate of the focal birds during playback was not correlated with the other response variables and showed a very different pattern from the aggressive response. Switching rate increased during unshared/synchronized trials and decreased during shared/ synchronized (i.e., song-type matching) trials. The tendency of the birds to refrain from switching when they were song-type matched by playback led to long bouts of matched-type countersinging. These results suggest that song-type matching locks two countersinging birds into a new level of interaction in which information other than aggressive motivation is exchanged.