scholarly journals Are signals of aggressive intent less honest in urban habitats?

2018 ◽  
Author(s):  
Çağlar Akçay ◽  
Michelle L. Beck ◽  
Kendra B. Sewall
Keyword(s):  
Communication Systems ◽  
Animal Communication ◽  
Acoustic Noise ◽  
Acoustic Properties ◽  
Visual Signal ◽  
Urban Habitats ◽  
Urban Birds ◽  
Urban Noise ◽  
Song Sparrows ◽  
Close Range

AbstractThe effect of urban noise on animal communication systems is one of the best examples of how anthropogenic change affects animal social behaviour. Urban noise often drives shifts in acoustic properties of signals but the consequences of noise for the honesty of signals – that is, how well they predict signaler behaviour, is unclear. Here we examine whether honesty of aggressive signaling changes in urban living song sparrows (Melospiza melodia). Aggressive signaling in song sparrows consists of close-range signals in two modalities that predict a subsequent attack: the low amplitude soft songs (an acoustic signal) and wing waves (a visual signal). Male song sparrows living in urban habitats display more territorial aggression than males living in rural habitats, but whether the honesty of close-range signals is affected by urbanization has not been examined. If soft songs are less effective in urban noise, we predict that they would be less reliably associated with attack in these habitats compared to rural habitats. We found that while acoustic noise was higher in urban habitats, the urban birds still sang more soft songs than rural birds during a simulated territorial intrusion. Furthermore, high rates of soft songs and low rates of loud songs predicted attacks in both habitats. Finally, we found evidence for a potential multimodal shift: urban birds tended to give proportionally more wing waves than soft songs than rural birds. These results indicate that urbanization might have a limited effect on the overall honesty of aggressive signals in song sparrows.

scholarly journals Are signals of aggressive intent less honest in urban habitats?

2019 ◽  
Author(s):  
Çağlar Akçay ◽  
Michelle L Beck ◽  
Kendra B Sewall
Keyword(s):  
Acoustic Noise ◽  
Visual Signals ◽  
Acoustic Properties ◽  
Urban Habitats ◽  
Urban Birds ◽  
Urban Noise ◽  
Song Sparrows ◽  
Soft Song ◽  
Close Range ◽  
Low Amplitude

Abstract How anthropogenic change affects animal social behavior, including communication is an important question. Urban noise often drives shifts in acoustic properties of signals but the consequences of noise for the honesty of signals—that is, how well they predict signaler behavior—is unclear. Here we examine whether honesty of aggressive signaling is compromised in male urban song sparrows (Melospiza melodia). Song sparrows have two honest close-range signals: the low amplitude soft songs (an acoustic signal) and wing waves (a visual signal), but whether the honesty of these signals is affected by urbanization has not been examined. If soft songs are less effective in urban noise, we predict that they should predict attacks less reliably in urban habitats compared to rural habitats. We confirmed earlier findings that urban birds were more aggressive than rural birds and found that acoustic noise was higher in urban habitats. Urban birds still sang more soft songs than rural birds. High rates of soft songs and low rates of loud songs predicted attacks in both habitats. Thus, while urbanization has a significant effect on aggressive behaviors, it might have a limited effect on the overall honesty of aggressive signals in song sparrows. We also found evidence for a multimodal shift: urban birds tended to give proportionally more wing waves than soft songs than rural birds, although whether that shift is due to noise-dependent plasticity is unclear. These findings encourage further experimental study of the specific variables that are responsible for behavioral change due to urbanization. Soft song, the low amplitude songs given in close range interactions, is an honest threat signal in urban song sparrows. Given its low amplitude, soft songs may be a less effective signal in noisy urban habitats. However, we found that soft song remained an honest signal predicting attack in urban habitats. We also found that birds may use more visual signals (rapid fluttering of wings) in urban habitats to avoid masking from acoustic noise.

scholarly journals Multi-modal communication: Song sparrows increase signal redundancy in noise

2019 ◽  
Author(s):  
Çağlar Akçay ◽  
Michael D. Beecher
Keyword(s):  
Animal Communication ◽  
Acoustic Noise ◽  
Low Frequency ◽  
Anthropogenic Noise ◽  
Visual Modality ◽  
Modal Shift ◽  
Song Sparrows ◽  
Show Evidence ◽  
Shift Hypothesis ◽  
Song Playback

AbstractAlthough the effects of anthropogenic noise on animal communication have been studied widely, most research on the effect of noise in communication has been on communication in a single modality. Consequently, how multimodal communication is affected by anthropogenic noise is relatively poorly understood. Here we ask whether song sparrows (Melospiza melodia) show evidence of plasticity in response to noise in two aggressive signals in acoustic and visual modalities. We test two hypotheses: (1) that song sparrows will shift signaling effort to the visual modality (the multi-modal shift hypothesis), and (2) that they will increase redundancy of their multi-modal signaling (the back-up hypothesis). We presented male song sparrows with song playback and a taxidermic mount with or without a low-frequency acoustic noise from a nearby speaker. We found that males did not switch their signaling effort to visual modality (i.e., wing waves) in response to the noise. However, the correlation between warbled soft songs and wing waves increased in the noise treatment, i.e. signals became more redundant. These results suggest that when faced with anthropogenic noise, song sparrows can increase redundancy of their multi-modal signals, which may aid in robustness of the communication system.

scholarly journals Multi-modal communication: song sparrows increase signal redundancy in noise

2019 ◽  
Vol 15 (10) ◽  
pp. 20190513
Author(s):  
Çağlar Akçay ◽  
Michael D. Beecher
Keyword(s):  
Animal Communication ◽  
Acoustic Noise ◽  
Low Frequency ◽  
Anthropogenic Noise ◽  
Visual Modality ◽  
Modal Shift ◽  
Song Sparrows ◽  
Show Evidence ◽  
Shift Hypothesis ◽  
Song Playback

Although the effects of anthropogenic noise on animal communication have been studied widely, most research on the effect of noise in communication has focused on signals in a single modality. Consequently, how multi-modal communication is affected by anthropogenic noise is relatively poorly understood. Here, we ask whether song sparrows ( Melospiza melodia ) show evidence of plasticity in response to noise in two aggressive signals in acoustic and visual modalities. We test two hypotheses: (i) that song sparrows will shift signalling effort to the visual modality (the multi-modal shift hypothesis) and (ii) that they will increase redundancy of their multi-modal signalling (the back-up signal hypothesis). We presented male song sparrows with song playback and a taxidermic mount with or without a low-frequency acoustic noise from a nearby speaker. We found that males did not switch their signalling effort to visual modality (i.e. wing waves) in response to the noise. However, the correlation between warbled soft songs and wing waves increased in the noise treatment, i.e. signals became more redundant. These results suggest that when faced with anthropogenic noise, song sparrows can increase the redundancy of their multi-modal signals, which may aid in the robustness of the communication system.

scholarly journals Vocal plasticity in a reptile

2017 ◽  
Vol 284 (1855) ◽  
pp. 20170451 ◽  
Author(s):  
Henrik Brumm ◽  
Sue Anne Zollinger
Keyword(s):  
Signal Detection ◽  
Communication Systems ◽  
Vocal Communication ◽  
Animal Communication ◽  
High Amplitude ◽  
Vocal Plasticity ◽  
Lombard Effect ◽  
Gekko Gecko ◽  
High Degree ◽  
Signalling Systems

Sophisticated vocal communication systems of birds and mammals, including human speech, are characterized by a high degree of plasticity in which signals are individually adjusted in response to changes in the environment. Here, we present, to our knowledge, the first evidence for vocal plasticity in a reptile. Like birds and mammals, tokay geckos ( Gekko gecko ) increased the duration of brief call notes in the presence of broadcast noise compared to quiet conditions, a behaviour that facilitates signal detection by receivers. By contrast, they did not adjust the amplitudes of their call syllables in noise (the Lombard effect), which is in line with the hypothesis that the Lombard effect has evolved independently in birds and mammals. However, the geckos used a different strategy to increase signal-to-noise ratios: instead of increasing the amplitude of a given call type when exposed to noise, the subjects produced more high-amplitude syllable types from their repertoire. Our findings demonstrate that reptile vocalizations are much more flexible than previously thought, including elaborate vocal plasticity that is also important for the complex signalling systems of birds and mammals. We suggest that signal detection constraints are one of the major forces driving the evolution of animal communication systems across different taxa.

scholarly journals Acoustic cues to individuality in wild male adult African savannah elephants (Loxodonta africana)

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10736
Author(s):  
Kaja Wierucka ◽  
Michelle D. Henley ◽  
Hannah S. Mumby
Keyword(s):  
Communication Systems ◽  
Animal Communication ◽  
Current Knowledge ◽  
Individual Recognition ◽  
Social Bonds ◽  
Loxodonta Africana ◽  
Mature Male ◽  
Acoustic Cues ◽  
Acoustic Parameters ◽  
Male Adult

The ability to recognize conspecifics plays a pivotal role in animal communication systems. It is especially important for establishing and maintaining associations among individuals of social, long-lived species, such as elephants. While research on female elephant sociality and communication is prevalent, until recently male elephants have been considered far less social than females. This resulted in a dearth of information about their communication and recognition abilities. With new knowledge about the intricacies of the male elephant social structure come questions regarding the communication basis that allows for social bonds to be established and maintained. By analyzing the acoustic parameters of social rumbles recorded over 1.5 years from wild, mature, male African savanna elephants (Loxodonta africana) we expand current knowledge about the information encoded within these vocalizations and their potential to facilitate individual recognition. We showed that social rumbles are individually distinct and stable over time and therefore provide an acoustic basis for individual recognition. Furthermore, our results revealed that different frequency parameters contribute to individual differences of these vocalizations.

scholarly journals Multimodal signalling in the North American barn swallow: a phenotype network approach

2015 ◽  
Vol 282 (1816) ◽  
pp. 20151574 ◽  
Author(s):  
Matthew R. Wilkins ◽  
Daizaburo Shizuka ◽  
Maxwell B. Joseph ◽  
Joanna K. Hubbard ◽  
Rebecca J. Safran
Keyword(s):  
Mate Choice ◽  
North American ◽  
Communication Systems ◽  
Animal Communication ◽  
Complex Signal ◽  
Network Approach ◽  
Barn Swallow ◽  
Complex Signals ◽  
The North ◽  
Phenotype Network

Complex signals, involving multiple components within and across modalities, are common in animal communication. However, decomposing complex signals into traits and their interactions remains a fundamental challenge for studies of phenotype evolution. We apply a novel phenotype network approach for studying complex signal evolution in the North American barn swallow ( Hirundo rustica erythrogaster ). We integrate model testing with correlation-based phenotype networks to infer the contributions of female mate choice and male–male competition to the evolution of barn swallow communication. Overall, the best predictors of mate choice were distinct from those for competition, while moderate functional overlap suggests males and females use some of the same traits to assess potential mates and rivals. We interpret model results in the context of a network of traits, and suggest this approach allows researchers a more nuanced view of trait clustering patterns that informs new hypotheses about the evolution of communication systems.

A comparison of two information theory approaches to animal communication systems

2001 ◽  
Vol 109 (5) ◽  
pp. 2429-2429
Author(s):  
Laurance R. Doyle ◽  
Jon M. Jenkins ◽  
Sean F. Hanser ◽  
Brenda McCowan
Keyword(s):  
Information Theory ◽  
Communication Systems ◽  
Animal Communication

Patterns of evolution in human speech processing and animal communication

1998 ◽  
Vol 21 (2) ◽  
pp. 282-283
Author(s):  
Michael J. Ryan ◽  
Nicole M. Kime ◽  
Gil G. Rosenthal
Keyword(s):  
Sexual Selection ◽  
Speech Processing ◽  
Communication Systems ◽  
Animal Communication ◽  
Low Noise ◽  
Communication Signals ◽  
Human Speech ◽  
Strong Selection ◽  
Processing Data ◽  
Receiver System

We consider Sussman et al.'s suggestion that auditory biases for processing low-noise relationships among pairs of acoustic variables is a preadaptation for human speech processing. Data from other animal communication systems, especially those involving sexual selection, also suggest that neural biases in the receiver system can generate strong selection on the form of communication signals.

scholarly journals Multimodal alarm behavior in urban and rural gray squirrels studied by means of observation and a mechanical robot

2010 ◽  
Vol 56 (3) ◽  
pp. 313-326 ◽  
Author(s):  
Sarah R. Partan ◽  
Andrew G. Fulmer ◽  
Maya A. M. Gounard ◽  
Jake E. Redmond
Keyword(s):  
Communication Systems ◽  
Sensory Modality ◽  
Multimodal Communication ◽  
Visual Signals ◽  
Urban Habitats ◽  
Multimodal Signals ◽  
Alarm Behavior ◽  
Alarm Signaling ◽  
Interesting Possibility ◽  
Multimodal Enhancement

Abstract Urbanization of animal habitats has the potential to affect the natural communication systems of any species able to survive in the changed environment. Urban animals such as squirrels use multiple signal channels to communicate, but it is unknown how urbanization has affected these behaviors. Multimodal communication, involving more than one sensory modality, can be studied by use of biomimetic mechanical animal models that are designed to simulate the multimodal signals and be presented to animal subjects in the field. In this way the responses to the various signal components can be compared and contrasted to determine whether the multimodal signal is made up of redundant or nonredundant components. In this study, we presented wild gray squirrels in relatively urban and relatively rural habitats in Western Massachusetts with a biomimetic squirrel model that produced tail flags and alarm barks in a variety of combinations. We found that the squirrels responded to each unimodal component on its own, the bark and tail flag, but they responded most to the complete multimodal signal, containing both the acoustic and the moving visual components, providing evidence that in this context the signal components are redundant and that their combination elicits multimodal enhancement. We expanded on the results of Partan et al. (2009) by providing data on signaling behavior in the presence and absence of conspecifics, suggesting that alarm signaling is more likely if conspecifics are present. We found that the squirrels were more active in the urban habitats and that they responded more to tail flagging in the urban habitats as compared to the rural ones, suggesting the interesting possibility of a multimodal shift from reliance on audio to visual signals in noisier more crowded urban habitats.

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