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 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 The fitness consequences of honesty: under-signalers have a survival advantage in song sparrows

2015 ◽  
Author(s):  
Çağlar Akçay ◽  
S. Elizabeth Campbell ◽  
Michael D. Beecher
Keyword(s):  
Evolutionary Biology ◽  
Survival Advantage ◽  
Future Research ◽  
Major Question ◽  
Song Sparrows ◽  
Soft Song ◽  
High Aggression ◽  
Close Range ◽  
Low Levels ◽  
Reliable Signaling

How honest or reliable signaling can evolve and be maintained has been a major question in evolutionary biology. The question is especially puzzling for a particular class of signals used in aggressive interactions: threat signals. Here we report a study on song sparrows (Melospiza melodia) in which we assayed males with playbacks on their territories to quantify their aggressiveness (flights and close proximity) and aggressive signaling levels (rates of soft song, a close range signal reliably predicting attack) and asked whether these traits affect individuals’ survival on territory. We found that the effect of aggressive signaling via soft song interacted with aggressive behaviors such that there was a negative correlational selection: among males with low aggression, those males that signaled at higher levels (over-signalers) had higher survival whereas among males with high aggression those that signaled at low levels (under-signalers) survived longer. In other words, males who deviate from reliable signaling have a survival advantage. These results, along with previous research that suggested most of the deviation from reliable signaling in this system is in the form of under-signaling (high aggression males signaling at low levels) pose a puzzle for future research on how this reliable signaling system is maintained.

scholarly journals The fitness consequences of honesty: under-signalers have a survival advantage in song sparrows

2015 ◽  
Author(s):  
Çağlar Akçay ◽  
S. Elizabeth Campbell ◽  
Michael D. Beecher
Keyword(s):  
Evolutionary Biology ◽  
Survival Advantage ◽  
Future Research ◽  
Major Question ◽  
Song Sparrows ◽  
Soft Song ◽  
High Aggression ◽  
Close Range ◽  
Low Levels ◽  
Reliable Signaling

How honest or reliable signaling can evolve and be maintained has been a major question in evolutionary biology. The question is especially puzzling for a particular class of signals used in aggressive interactions: threat signals. Here we report a study on song sparrows (Melospiza melodia) in which we assayed males with playbacks on their territories to quantify their aggressiveness (flights and close proximity) and aggressive signaling levels (rates of soft song, a close range signal reliably predicting attack) and asked whether these traits affect individuals’ survival on territory. We found that the effect of aggressive signaling via soft song interacted with aggressive behaviors such that there was a negative correlational selection: among males with low aggression, those males that signaled at higher levels (over-signalers) had higher survival whereas among males with high aggression those that signaled at low levels (under-signalers) survived longer. In other words, males who deviate from reliable signaling have a survival advantage. These results, along with previous research that suggested most of the deviation from reliable signaling in this system is in the form of under-signaling (high aggression males signaling at low levels) pose a puzzle for future research on how this reliable signaling system is maintained.

scholarly journals Aggressiveness, reliable signaling and survival in a wild songbird

2015 ◽  
Author(s):  
Çağlar Akçay ◽  
S. Elizabeth Campbell ◽  
Michael D. Beecher
Keyword(s):  
Evolutionary Biology ◽  
Future Research ◽  
Major Question ◽  
Song Sparrows ◽  
Soft Song ◽  
Close Proximity ◽  
High Aggression ◽  
Close Range ◽  
Low Levels ◽  
Reliable Signaling

The evolution and maintenance of honest or reliable signaling has been a major question in evolutionary biology. The question is especially puzzling for a particular class of signals used in aggressive interactions: threat signals. Here we report a study on song sparrows (Melospiza melodia) in which we assayed males with playbacks in their territories to quantify their aggressiveness (flights, and close proximity) and aggressive signaling levels (rates of soft song, a close range signal reliably predicting attack) and asked whether these traits affect individuals’ survival on territory. We found that the effect of aggressive signaling via soft song interacted with aggressive behaviors such that there was a negative correlational selection: among males with low aggression, those males that signaled at higher levels (over-signalers) had higher survival whereas among males with high aggression those that signaled at low levels (under-signalers) survived longer. In other words, males who deviate from reliable signaling have a survival advantage. These results, along with previous research that suggested most of the deviation from reliable signaling in this system is in the form of under-signaling (high aggression males signaling at low levels) pose a puzzle for future research on how this reliable signaling system is maintained.

A variety of surface waves in ocean-bottom DAS records

2021 ◽  
Author(s):  
Zack Spica ◽  
Loïc Viens ◽  
Jorge Castillo Castellanos ◽  
Takeshi Akuhara ◽  
Kiwamu Nishida ◽  
...  
Keyword(s):  
Surface Wave ◽  
Acoustic Waves ◽  
Fiber Optic ◽  
Acoustic Noise ◽  
Seismic Exploration ◽  
Ocean Bottom ◽  
Wide Range ◽  
Ocean Layer ◽  
Noise Cross Correlation ◽  
Low Amplitude

<p>Distributed acoustic sensing (DAS) can transform existing telecommunication fiber-optic cables into arrays of thousands of sensors, enabling meter-scale recordings over tens of kilometers. Recently, DAS has demonstrated its utility for many seismological applications onshore. However, the use of offshore cables for seismic exploration and monitoring is still in its infancy.<br>In this work, we introduce some new results and observations obtained from a fiber-optic cable offshore the coast of Sanriku, Japan. In particular, we focus on surface wave retrieved from various signals and show that ocean-bottom DAS can be used to extract dispersion curves (DC) over a wide range of frequencies. We show that multi-mode DC can be easily extracted from ambient seismo-acoustic noise cross-correlation functions or F-K analysis. Moderate magnitude earthquakes also contain multiple surface-wave packets that are buried within their coda. Fully-coupled 3-D numerical simulations suggest that these low-amplitude signals originate from the continuous reverberations of the acoustic waves in the ocean layer. </p>

Acoustics of the mountain pine beetle (Dendroctonus ponderosae) (Curculionidae, Scolytinae): sonic, ultrasonic, and vibration characteristics

2013 ◽  
Vol 91 (4) ◽  
pp. 235-244 ◽  
Author(s):  
A.J. Fleming ◽  
A.A. Lindeman ◽  
A.L. Carroll ◽  
J.E. Yack
Keyword(s):  
Bark Beetles ◽  
Mountain Pine Beetle ◽  
Dendroctonus Ponderosae ◽  
Laser Doppler Vibrometer ◽  
Future Research ◽  
Acoustic Signaling ◽  
Mountain Pine ◽  
Pine Beetle ◽  
Close Range ◽  
Low Amplitude

Acoustic signaling is widespread in bark beetles (Scolytinae), although little is known about the physical characteristics of signals, how they are transmitted, and how they differ among behavioural contexts. Signals were studied in the male mountain pine beetle (Dendroctonus ponderosae Hopkins, 1902) during stress, male–female, and male–male interactions. Sounds are broadband with significant energy in the ultrasound (peaks between 15 and 26 kHz) and low amplitude (55 and 47 dB SPL at 2 and 4 cm, respectively), indicating that signaling functions at close range. Signal trains vary among contexts primarily in the proportions of chirp types. Chirps were categorized as being simple or interrupted, with the former having significantly lower tooth strike rates and shorter chirp durations. Stress chirps are predominantly simple with characteristics resembling other insect disturbance signals. Male–female interactions begin with the male producing predominantly interrupted chirps prior to gallery entrance, followed by simple chirps. Male–male (rivalry) chirps are predominantly simple, with evidence of antiphonal calling. Substrate-borne vibrations were detectable with a laser-doppler vibrometer at short distances (1–3 cm), suggesting that sensory organs could be tuned to either air or substrate-borne vibrations. These results have important implications for future research on the function and reception of acoustic signals in bark beetles.

Soft song in song sparrows: response of males and females to an enigmatic signal

2007 ◽  
Vol 61 (8) ◽  
pp. 1267-1274 ◽  
Author(s):  
Rindy C. Anderson ◽  
Stephen Nowicki ◽  
William A. Searcy
Keyword(s):  
Song Sparrows ◽  
Soft Song ◽  
Males And Females

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.

Soft song is a reliable signal of aggressive intent in song sparrows

2012 ◽  
Vol 66 (11) ◽  
pp. 1503-1509 ◽  
Author(s):  
Christopher N. Templeton ◽  
Çağlar Akçay ◽  
S. Elizabeth Campbell ◽  
Michael D. Beecher
Keyword(s):  
Song Sparrows ◽  
Soft Song

scholarly journals Urban birds have broader environmental tolerance

2007 ◽  
Vol 3 (6) ◽  
pp. 670-673 ◽  
Author(s):  
Frances Bonier ◽  
Paul R Martin ◽  
John C Wingfield
Keyword(s):  
Urban Environments ◽  
Urban Habitats ◽  
Urban Birds ◽  
Environmental Tolerance ◽  
Global Comparison ◽  
Ecological Flexibility

Urbanization dramatically changes the composition and diversity of biotic communities. The characteristics distinguishing species that persist in urban environments, however, are poorly understood. Here we test the hypothesis that broadly adapted organisms are better able to tolerate urbanization, using a phylogenetically controlled, global comparison of birds. We compared elevational and latitudinal distributions of 217 urban birds found in 73 of the world's largest cities with distributions of 247 rural congeners to test the hypothesis that urban birds possess broader environmental tolerance. Urban birds had markedly broader environmental tolerance than rural congeners, as estimated by elevational and latitudinal distributions. Our results suggest that broad environmental tolerance may predispose some birds to thrive in urban habitats. The mechanisms mediating such environmental tolerance warrant further investigation, but probably include greater behavioural, physiological and ecological flexibility.

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