Territorial Songbirds Research Articles

Interspecific avoidance of song overlap in tropical songbirds: species-specific responses to acoustically similar and different intruders

To ensure effective acoustic communication, signals should reach receivers in the least distorted form possible. Animals use various short- and long-term strategies to avoid signal degradation and masking. However, we still have an insufficient understanding of how animals’ vocal behaviour is impacted by the vocalisations of other animals in their acoustic communities. We experimentally examined how two tropical, sedentary, territorial songbirds in Western Uganda—the scaly-breasted illadopsis (Illadopsis albipectus) and the green-backed camaroptera (Camaroptera brachyura)—modify their singing behaviour after the simulated appearance of new, unfamiliar acoustic competitors, whose songs vary in similarity to those of the species studied. We found that scaly-breasted illadopsis sang significantly less during the playback of songs of acoustically similar species than of acoustically different species or silence and avoided song overlapping with acoustically similar species but not with acoustically different species. Green-backed camaroptera sang significantly more during the playback of both acoustically similar and different simulated intruders than during the control containing silence, and patterns of overlap with the songs of both the acoustically similar and different species were random. Our results show that even a single-point noise source present within a territory can modify a bird’s singing behaviour. The new sound may affect species differently, depending in part on the level of acoustic similarity with the species’ song. To mitigate the effect of song masking, different species may use different strategies, such as temporal avoidance or signal redundancy. Studies examining the adaptive abilities of species in natural and modified habitats are needed to predict the consequences of changes in acoustic community structure.Significance statementTo ensure effective communication, birds may use different strategies to avoid signal masking in common acoustic space, particularly in the complex acoustic environment of a tropical forest. While multiple studies have focused on responses to interference caused by anthropogenic noise, the effect of new individual species on the acoustic community structure has received little attention. We simulated intrusions by unfamiliar species with different levels of song similarity into the territories of two tropical songbird species. The appearance of new simulated acoustic intruders modified the birds’ singing behaviour, but the two study species responded differently. These results suggest that the level of acoustic similarity, as well as the species ecology, may affect the species response, which may be particularly important when predicting the effects of new species appearance as a result of changes in habitat and climate.

Eavesdropping on conspecific alarm calls links birds across territory borders into a population-wide information network

Animal communication, including the transmission of risk-related information, has long been recognized as occurring in a network, rather than being limited to signaller–receiver dyadic interactions. However, it is rare for studies on communication to explicitly incorporate a network approach and for network studies to focus on communication interactions and information transmission in nongrouping species. Consequently, the properties of communication networks and the extent to which risk-related information can spread through populations of territorial animals remain largely unexplored. Here, I examined the structure and spatial extent of eavesdropping networks by studying alarm calls in wood warblers, Phylloscopus sibilatrix, small, territorial songbirds inhabiting temperate European forests. Using a playback experiment, I first established the active space of wood warblers' alarm signals, that is, how the strength of antipredator responses to conspecific alarm calls varies as a function of distance between signallers and receivers. Next, I combined social network analysis and fine-scale, long-term data on wood warblers' territory distribution to delineate spatially explicit alarm call eavesdropping networks and to explore the potential for risk-related information transmission at the population level. Response strength of wood warblers to conspecific calls decreased with increasing distance to callers, suggesting distance-dependent eavesdropping. However, each year the majority of individuals occupied territories within the active space of alarm signals of multiple neighbours and could reach information from even more of them via indirect links. Moreover, the patterns of connections between individuals were generally similar across years, suggesting that basic network properties remain stable over time. This study shows that during the spring breeding season, individual birds are interlinked with conspecifics across territory borders into population-wide information webs, in which risk-related information can readily spread across large spatial scales. In turn, this highlights the social environment as an important dimension of individuals’ niches even in otherwise territorial animals.

The communicative value of complex singing in passerine birds

Birdsong is one of the most complex signals in the animal world, as it may consist of many different sounds grouped according to certain rules. Singing acts as a distant signal, indicating, e.g., the species and gender identity of the singer. However, territorial songbirds also use singing as an interactive social signal during territorial disputes, as well while interacting with female. In these contexts, males vary the type and timing of their songs to convey graded information about their motivational state, and those variations can play a role in communication. In this review, we considered how male songbirds vary their singing in territorial context. To study such variations, researchers usually simulated territorial intrusion by broadcasting conspecific singing in territories, including singing modified in a manner necessary for the researcher. For comparison, we considered briefly how singing vary in intersexual context. The author of the paper focuses on the role of singing complexity in communication. Therefore, not all known context-dependent changes in singing are considered, but only those related to “complexity”: the diversity of song/sound types and the transitional patterns of different song/sound types in the course of singing. Our review has shown that males change their singing when they detect environmental changes such as the appearance of a female or a competitor as follows: 1) song rate increases, 2) syllable rate increases, 3) song-type switching rate increases, 4) song-type diversity increases (i.e., the observed repertoire size), and 5) longer and more complex songs are predominantly used. In some species, the song bout organization may also change, but the data is still scarce. Typically, one or more, but not all the aforementioned acoustic behaviors have been found in a given song-bird species. All these behaviors (tactics) come down to a single strategy, namely: maximizing the acoustic diversity over a short period of time (e.g., several minutes), that is, increasing the number of different song and/or note types. The proximate causes of how the increased acoustic diversity work in the territorial competition context might lie in a sensory, or perceptual bias of the receiver. Namely, habituation should occur to repeated presentation of the same song type faster than to presentation of different song types. Therefore, by vocalizing more diversely, males more effectively influence the signal recipient’s behavior.

Local conspecific density does not influence reproductive output in a secondary cavity-nesting songbird

AbstractDensity dependence is a conceptual cornerstone of avian population biology and, in territorial songbirds, past research has emphasized interactions among food limitation, density, and reproduction. Documenting the importance of density effects is central to understanding how selective forces shape life histories and population dynamics. During the 2008–2011 breeding seasons, we nearly doubled overall conspecific breeding densities on study sites, and manipulated nest box spacing to increase local breeding densities (defined as the number of pairs breeding within 200 m of a pair’s nest) of a secondary cavity-nesting songbird, the Prothonotary Warbler (Protonotaria citrea). Our primary objective was to test for effects of food limitation, as mediated by conspecific local densities, on measures of productivity. We monitored breeding pairs and recorded the total number of fledglings produced along with several components of reproductive output (clutch size, hatching success, nestling survival, and probability of attempting a second brood), rates of nestling provisioning, and nestling body condition prior to fledging. We predicted that if the availability of food were affected by local densities, then one or more of these parameters measuring reproduction would be affected negatively. We did not detect an effect of local density on total reproductive output or its components despite our vast range of local densities (1–27 pairs; i.e. 0.16–2.23 pairs ha–1). Further, we also did not detect differences in nestling provisioning rates and nestling body condition relative to local density. By breeding in a productive ecosystem rich in food resources, these warblers appear to avoid reduced reproductive output when breeding in high densities. Whereas density-dependent food limitation may commonly reduce reproductive output in many species, the ecological circumstances underlying when it does not occur merit further investigation and may provide new insights into what is driving territoriality and what are the primary factors affecting individual fitness.

Development of Meaningful Vocal Signals in a Juvenile Territorial Songbird (Gymnorhina tibicen) and the Dilemma of Vocal Taboos Concerning Neighbours and Strangers.

Simple SummaryOwnership of a territory is very important for many vertebrates. Some songbird species, such as the Australian magpie, have all-year-round, not just seasonal, territories. Hence, there is a good deal at stake in holding on to such a territory. It requires vigilance, experience, an excellent memory, and most of all, effective vocal communication. There is a strong relationship between successful territorial ownership, strong social bonds, and the health, survival, even the life-span and overall cognitive development of offspring. Yet, we know next to nothing as to how juveniles acquire their vocal skills and apply these appropriately, including territorial signals. Clearly, juveniles need to learn about territoriality, i.e., learn about potential enemies, recognise which birds are neighbours, and what constitutes an incursion into territory. The results of this extensive field study unexpectedly revealed that juveniles did not use more than half of all the vocalisations adults expressed and they needed a long time (three months post fledging) to distinguish between neighbour and stranger calls, attributing differential importance to each. It also showed that the territorial call was learned but was expected by adults not be used by juveniles, limiting their ability to communicate. A range of other calls associated with territoriality were also not expressed, possibly because only territory owners could do so.Young territorial songbirds have calls to learn, especially calls that may be vital for maintaining territory. Territoriality is largely reinforced and communicated by vocal signals. In their natal territory, juvenile magpies (Gymnorhina tibicen) enjoy protection from predators for 8–9 months. It is not at all clear, however, when and how a young territorial songbird learns to distinguish the meaning of calls and songs expressed by parents, conspecifics, neighbours, and heterospecifics, or how territorial calls are incorporated into the juvenile’s own repertoire. This project investigated acquisition and expression of the vocal repertoire in juvenile magpies and assessed the responses of adults and juveniles to playbacks of neighbour and stranger calls inside their territory. The results reported here identify age of appearance of specific vocalisations and the limits of their expression in juveniles. One new and surprising result was that many types of adult vocalisation were not voiced by juveniles. Playbacks of calls of neighbours and strangers inside the natal territory further established that adults responded strongly but differentially to neighbours versus strangers. By contrast, juveniles needed months before paying any attention to and distinguishing between neighbour and stranger calls and eventually did so only in non-vocal ways (such as referral to adults). These results provide evidence that auditory perception not only includes recognition and memory of neighbour calls but also an assessment of the importance of such calls in the context of territoriality.

Interspecific aggression by the Swainson's Thrush (Catharus ustulatus) may limit the distribution of the threatened Bicknell's Thrush (Catharus bicknelli) in the Adirondack Mountains

ABSTRACT Bicknell's Thrush (Catharus bicknelli) is a threatened species that inhabits high-elevation spruce–fir forests in the northeastern United States. Bicknell's Thrush populations are predicted to shift upslope in response to global warming, leading to local extinctions on mountains that lack the elevational extent to accommodate such shifts. However, biotic interactions may influence how montane species respond to changing abiotic conditions. In territorial songbirds, for example, aggression from dominant low-elevation species has been hypothesized to combine with warming temperatures to “push” populations of subordinate montane species upslope at a faster rate than in the absence of interspecific aggression. This “push” hypothesis could apply to Bicknell's Thrushes: the related Swainson's Thrush (Catharus ustulatus) inhabits lower elevations, Bicknell's Thrushes are largely confined to mountaintops, and interspecific aggression by Swainson's Thrushes toward Bicknell's Thrushes has been anecdotally ...

Song trait similarity in great tits varies with social structure.

For many animals, long-range signalling is essential to maintain contact with conspecifics. In territorial species, individuals often have to balance signalling towards unfamiliar potential competitors (to solely broadcast territory ownership) with signalling towards familiar immediate neighbours (to also maintain so-called “dear enemy” relations). Hence, to understand how signals evolve due to these multilevel relationships, it is important to understand how general signal traits vary in relation to the overall social environment. For many territorial songbirds dawn is a key signalling period, with several neighbouring individuals singing simultaneously without immediate conflict. In this study we tested whether sharing a territory boundary, rather than spatial proximity, is related to similarity in dawn song traits between territorial great tits (Parus major) in a wild personality-typed population. We collected a large dataset of automatized dawn song recordings from 72 unique male great tits, during the fertile period of their mate, and compared specific song traits between neighbours and non-neighbours. We show here that both song rate and start time of dawn song were repeatable song traits. Moreover, neighbours were significantly more dissimilar in song rate compared to non-neighbours, while there was no effect of proximity on song rate similarity. Additionally, similarity in start time of dawn song was unrelated to sharing a territory boundary, but birds were significantly more similar in start time of dawn song when they were breeding in close proximity of each other. We suggest that the dissimilarity in dawn song rate between neighbours is either the result of neighbouring great tits actively avoiding similar song rates to possibly prevent interference, or a passive consequence of territory settlement preferences relative to the types of neighbours. Neighbourhood structuring is therefore likely to be a relevant selection pressure shaping variation in territorial birdsong.

Conspecific effect on habitat selection of a territorial cavity-nesting bird

The simulated presence of conspecifics has been proposed to attract territorial songbirds to protect nesting areas when the habitat is being disturbed by human activities. We studied the effects of conspecifics on the nest-site selection of the Thorn-tailed Rayadito (Aphrastura spinicauda; Furnariidae), a forest songbird that depends on cavities for nesting. Plantations represent usable habitat for foraging, but the scarcity of cavities restricts their use during the breeding period. The use of nest boxes is a documented measure to mitigate the negative effect of plantations on cavity users. We installed nest boxes in a plantation of Pinus radiata in south-central Chile, using the simulated presence of conspecifics as a potential tool to attract rayaditos to new available sites to nest. We simulated the presence of conspecifics through playback during 45 days prior nest building. Our results showed two contrasting outcomes. Firstly, conspecific simulation attracts rayaditos, by increasing their density before playback experiments by 75%. Secondly, rayaditos tended to avoid playback treatment sites as nesting started. The establishment of nests occurred 71% of the time and started 20 days earlier in control sites compared to playback treatment. Other secondary cavity-nesting birds, such as the House Wren (Troglodytes aedon; Troglodytidae) and White-throated Treerunner (Pygarrhichas albogularis; Furnariidae), also avoided playback plots as nesting sites. The scarcity of cavities in pine plantations may increase the aggressive defense of breeding territories, making cavity-nesting birds move to other previously known vacant sites to nest when they listen other birds in the nesting site. It is highly recommended to assess the behavioral response to conspecific and heterospecific birds before the establishment of a management measure aiming to attract or discourage the presence of a target species.

Team of rivals: alliance formation in territorial songbirds is predicted by vocal signal structure

Cooperation and conflict are regarded as diametric extremes of animal social behaviour, yet the two may intersect under rare circumstances. We here report that territorial competitors in a common North American songbird species, the chipping sparrow (Spizella passerina), sometimes form temporary coalitions in the presence of simulated territorial intruders. Moreover, analysis of birds' vocal mating signals (songs) reveals that coalitions occur nearly exclusively under specific triadic relationships, in which vocal performances of allies and simulated intruders exceed those of residents. Our results provide the first evidence that animals like chipping sparrows rely on precise assessments of mating signal features, as well as relative comparisons of signal properties among multiple animals in communication networks, when deciding when and with whom to form temporary alliances against a backdrop of competition and rivalry.

Neighbours' talk: interspecific choruses among songbirds

In territorial songbirds, duets between mates represent one of the best-known examples of communal display, with the main function being the defence of joint resources. In this study, we found evidence of a coordinated choral display performed by neighbouring heterospecific songbirds. In such choruses, most of the participating species perform a deliberate temporal overlap of songs, thus suggesting agonistic behaviour. However, they then utilize a complex form of behaviour to avoid signal jamming, making the aggressive purpose unlikely. We define these displays as “coordinated interspecific choruses”. We recorded dusk choruses of songbirds living in a mixed turkey oak wood in central Italy, and then carried out a niche overlap analysis using null models that were intended for investigations of concurrent emissions of songs, finding that species tend to sing concurrently instead of using the refractory period of another species. Among the species singing concurrently, about half used the same frequency range, but instead of finding considerable spectral overlap between their vocalizations, the number of real spectral overlaps was lower than would be expected by chance. We propose a tentative explanation for this, where such choruses are the expression of the existence of a neighbourhood of different species that has evolved a communal signal that is similar to that used by mates in a pair, i.e. coordinated vocalizations. As coordination requires experience of each other's songs, we propose that evolution has selected individuals that are more skilled at learning heterospecific songs.

Evidence for multicontest eavesdropping in chickadees

Animals eavesdrop on dyadic interactions between other individuals to gather information for future mate choice and territory defense decisions. The capacity for eavesdroppers to combine information gathered from overhearing multiple two-way interactions is poorly studied. We tested whether inexperienced (second year) and older (after second year) male black-capped chickadees (Poecile atricapillus) eavesdrop on rivals' song contests to evaluate the relative threat levels of multiple unfamiliar territorial intruders. We used a multiple speaker playback experiment to simulate 3 male territorial intruders (A, B, and C) engaging in 2 successive dyadic song contests, presenting focal males with the information that A was more threatening than B, and B was more threatening than C. We then assayed the response of focal males when presented with simulated intruders A and C without relative information. We predicted that males would defend against the intruder perceived to be the greater threat. Focal males initially responded toward the more threatening intruder (A) significantly more than the less threatening intruder (C), consistent with our predictions. Older birds approached the more threatening intruder (A) significantly more than the less threatening intruder (C), whereas young males showed more variable responses. Our results suggest that male chickadees were able to acquire relative threat information from separate song contests that influenced their responses toward rivals paired in novel contests. These findings indicate that territorial songbirds in communication networks may be capable of integrating information gathered through eavesdropping on multiple interactions.

Win-stay, lose-switch and public information strategies for patch fidelity of songbirds with rare extra-pair paternity

Determining where organisms breed and understanding why they breed in particular locations are fundamental biological questions with conservation implications. Breeding-site fidelity is common in migratory, territorial songbirds and is typically thought to occur following reproductive success with a social mate and success of nearby conspecifics. It is currently unknown if frequency of extra-pair paternity in a population influences use of information about reproductive success of nearby conspecifics for site fidelity decisions. We investigated patch fidelity of white-eyed vireos (Vireo griseus) based on reproductive success and quantified frequency of extra-pair paternity. We found support only for females making patch fidelity decisions following reproductive success with a social mate. Patch fidelity of males was not associated with reproductive success of nearby conspecifics, suggesting males may not use this information when extra-pair paternity is infrequent or the association is non-existent in this species.

Vocal matching by orange-fronted conures (Aratinga canicularis)

The functions of vocal matching have been clarified in territorial songbirds, compositionally stable groups of birds and mammals, and species with multiple alarm or assembly signals. The functions of vocal matching are less well understood in fission/fusion species that are non-territorial, live in groups with variable composition, and lack multiple alarm signals. Here we present the results of interactive playbacks in a fission/fusion parrot species, the orange-fronted conjure (Aratinga canicularis), that provide evidence of vocal matching. A randomly selected loud contact call (chee) per trial was played to passing wild flocks and short-term captives in Costa Rica. Of the trials where subjects interacted, 30% of wild flocks and 21% of captive trials showed significantly linear or curvilinear changes in similarity between the stimulus and response chees over the course of the trial. Surprisingly, both convergent and divergent sequences were observed, and many trials lacking a single trend showed disjunct changes in stimulus-response similarity. These results suggest that chee exchanges prior to flock fusions are not simply an exchange of greetings but are more likely some form of negotiation. This would explain the presence of convergent, divergent, and variable patterns of stimulus-response similarity seen in our experiments.

Dynamic neuromodulation of aggression by vasotocin: influence of social context and social phenotype in territorial songbirds

The homologous neuropeptides vasotocin (VT) and vasopressin (VP) influence agonistic behaviours across many taxa, but peptide-behaviour relationships are complex and purportedly species-specific. Putative species-specific effects in songbirds are confounded with context, however, such that territorial species have been tested only in resident-intruder paradigms and gregarious species have been tested only in a mate competition paradigm. Using the territorial violet-eared waxbill (Estrildidae: Uraeginthus granatina), we now show that a V(1a) receptor antagonist reduces male aggression during mate competition (as in gregarious finches), but does not affect resident-intruder aggression in dominant males. However, the V(1a) antagonist disinhibits aggression in less aggressive (typically subordinate) males. These results are consistent with recent data on the activation of different VT cell groups during positive and negative social interactions. Thus, VT influences aggression similarly across territorial and gregarious species, but in context- and phenotype-specific ways that probably reflect the differential activation of discrete VT cell groups.

Constrained Performance in a Communication Network: Implications for the Function of Song‐Type Matching and for the Evolution of Multiple Ornaments

Many species of territorial songbirds exhibit a behavior known as song-type matching, in which a male sings the same song type that his neighbor is singing. Song-type matching is associated with increased aggression, but researchers have not come to a consensus on its adaptive function. Building on studies that identify singing performance as a variable relevant to sexual selection, we hypothesize that higher-performance singers benefit from matching their opponent's song type because matching improves eavesdroppers' ability to compare the two males' performances. We present a model of song-type choice that predicts that males that can outperform their rivals benefit by matching. In contrast, lower-performance males should avoid both matching and being matched. Our hypothesis is compatible with some existing hypotheses of song-matching function, but it is not compatible with the hypothesis that song matching is a conventional signal of aggression. We offer unique predictions that could be used to test our idea. We speculate that lower-performance individuals might have driven the evolution of repertoire complexity because they stand to benefit from novel, unmatchable songs. The phenomenon that dissimilar signals are less accurately compared than similar signals may favor the evolution of multiple ornaments and of plastic signal development (e.g., song learning) in general.

Coordination between the sexes for territorial defence in a duetting fairy-wren

In territorial songbirds both sexes depend on possession of a territory, yet its defence is traditionally regarded as the domain of male birds. Studies on duetting species have examined both male and female roles in territorial defence, often focusing on potential reproductive conflict between the pair members. Surprisingly, interactions between defending pair members are rarely investigated. We combined observations on undisturbed pairs of purple-crowned fairy-wrens, Malurus coronatus, with experimental simulation of a strong territorial threat to quantify coordination between partners during territorial defence. Pairs formed strongly cohesive partnerships: males and females naturally spent a high proportion of time close together (75% within 5 m) in dense riparian habitat, and coordinated half their songs to form duets. Partners that spent more time close together also coordinated more of their songs to form duets. When we presented playback simulating paired intruders, females responded as aggressively as males. Intensity of approach to the playback speaker was highly correlated within pairs. Spatial coordination between partners increased dramatically when they responded to simulated intrusion so that they spent virtually all their time within 2 m of one another, and most of the songs they sang were coordinated to form duets. We conclude that the highly coordinated vocal and approach responses of male and female purple-crowned fairy-wrens to simulated intrusion in the nonbreeding season are not coincidental, or a consequence of sexual conflict over mating, but instead are likely to represent cooperative territorial defence of a valuable shared resource.

Frequency matching, overlapping and movement behaviour in diurnal countersinging interactions of black-capped chickadees

Animal signalling contests are used by males to advertise to choosy females and to repel male competitors. During countersinging interactions in songbirds, males vary the type and timing of songs with respect to their opponent's behaviour. In black-capped chickadees, Poecile atricapillus, frequency matching and song overlapping appear to be important in territory defence and mate attraction. We studied frequency matching and overlapping behaviour during 100 naturally occurring diurnal song contests among male chickadees using an Acoustic Location System (ALS). The ALS consisted of 16 microphones that recorded countersinging interactions across multiple territories simultaneously, allowing us to triangulate the position of individuals based on delays in sound arrival at each microphone. We used the ALS to record 10 neighbourhoods of chickadees whose relative dominance status had been tabulated during the preceding winter. In 80% of contests there was at least one instance of overlapping between the contestants. In 37% of contests, the contestants were frequency matched within 50 Hz. Neither overlapping nor matching occurred at levels different from those expected by chance. However, contests that contained frequency matching had significantly more instances of overlapping than nonmatched contests. There were no rank-related differences in the proportion of opponents' songs that were frequency matched or overlapped. In using an Acoustic Location System to record entire neighbourhoods of territorial songbirds, this study is the first to quantify song matching and overlapping by free-living animals in the context of natural countersinging exchanges between familiar territorial neighbours.

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.

Conspecific attraction in a grassland bird, the Baird's Sparrow

Territorial songbirds generally use song to defend territories and attract mates, but conspecific song may also serve as a cue to attract other male songbirds to a breeding site. Although known to occur in some colonial and forest-associated species, only recently have investigators examined conspecific attraction in grassland species. We used a playback experiment to examine the possible role of conspecific attraction for males searching for potentially suitable breeding habitat in a grassland specialist, the Baird's Sparrow (Ammodramus bairdii). Experimental playback plots and control plots with similar landscape and vegetation characteristics were established at two sites in North Dakota. Baird's Sparrows colonized three of six experimental plots and none of six control plots. Males on experimental plots established territories adjacent to the playback stations and were sometimes observed counter-singing with the playback of conspecific songs. Vegetation characteristics were similar on all study plots, and did not explain differences in bird density on our treatment plots. Although we found that playback of conspecific songs attracted male Baird's Sparrows to previously unoccupied, potentially suitable habitat, further experiments are needed to examine the importance of conspecific attraction relative to other cues that birds may use, such as vegetation features. The conservation and management implications of conspecific attraction are not completely understood, but the presence of conspecifics should be considered as a potential cue in habitat selection by all species of birds. SINOPSIS. Atracci´ on de cong´ eneres en aves de hierbazales Ammodramus bairdii Las aves canoras territoriales generalmente usan su canto para defender sus territorios y atraer parejas prospectivas. Sin embargo, el canto de congtambise puede usar como una pista para atraer a otros machos a ´ areas

Display Plasticity in Response to a Robotic Lizard: Signal Matching or Song Sharing in Lizards?

AbstractMany territorial songbirds alter the structure of their songs after listening to and interacting repeatedly with the same neighbors. Here, we use a robotic lizard to test for similar learned changes in signal structure in male Sagebrush lizards, Sceloporus graciosus. Subjects were exposed to two types of headbob displays (species‐typical and unusual) both in short‐term tests and in repeated exposures for 10 d. We found no evidence for immediate changes in signal structure to match a particular opponent (signal matching) or long‐term changes after repeated exposure (‘song’ sharing). If anything, the lizards’ displays became less like that of the robotic stimulus over time. Further tests of other taxa are needed to identify the evolutionary forces that lead to these forms of behavioral plasticity and to determine whether song sharing and signal matching are unique characteristic of songbirds. Lizards also became more agitated and produced more highly aggressive displays of their own when confronted with headbob displays that violated the basic syntactic structure of their display system, confirming that they were paying attention to subtle differences in display structure despite the artificial nature of the treatments. Thus, our study also adds to the growing evidence supporting the use of robotic playbacks to study animal communication.