scholarly journals Alarming features: birds use specific acoustic properties to identify heterospecific alarm calls

2013 ◽  
Vol 280 (1754) ◽  
pp. 20122539 ◽  
Author(s):  
Pamela M. Fallow ◽  
Benjamin J. Pitcher ◽  
Robert D. Magrath
Keyword(s):  
Frequency Modulation ◽  
Alarm Call ◽  
Acoustic Properties ◽  
Alarm Calls ◽  
Acoustic Similarity ◽  
Acoustic Features ◽  
Alarm Signal ◽  
Antipredator Response ◽  
Malurus Cyaneus

Vertebrates that eavesdrop on heterospecific alarm calls must distinguish alarms from sounds that can safely be ignored, but the mechanisms for identifying heterospecific alarm calls are poorly understood. While vertebrates learn to identify heterospecific alarms through experience, some can also respond to unfamiliar alarm calls that are acoustically similar to conspecific alarm calls. We used synthetic calls to test the role of specific acoustic properties in alarm call identification by superb fairy-wrens, Malurus cyaneus . Individuals fled more often in response to synthetic calls with peak frequencies closer to those of conspecific calls, even if other acoustic features were dissimilar to that of fairy-wren calls. Further, they then spent more time in cover following calls that had both peak frequencies and frequency modulation rates closer to natural fairy-wren means. Thus, fairy-wrens use similarity in specific acoustic properties to identify alarms and adjust a two-stage antipredator response. Our study reveals how birds respond to heterospecific alarm calls without experience, and, together with previous work using playback of natural calls, shows that both acoustic similarity and learning are important for interspecific eavesdropping. More generally, this study reconciles contrasting views on the importance of alarm signal structure and learning in recognition of heterospecific alarms.

scholarly journals Recognition of other species' aerial alarm calls: speaking the same language or learning another?

2008 ◽  
Vol 276 (1657) ◽  
pp. 769-774 ◽  
Author(s):  
Robert D Magrath ◽  
Benjamin J Pitcher ◽  
Janet L Gardner
Keyword(s):  
Sympatric Species ◽  
Specific Structure ◽  
Geographical Range ◽  
Alarm Calls ◽  
Acoustic Similarity ◽  
Complex Task ◽  
Signal Design ◽  
Interspecific Recognition ◽  
Malurus Cyaneus

Alarm calls given by other species potentially provide a network of information about danger, but little is known about the role of acoustic similarity compared with learning in recognition of heterospecific calls. In particular, the aerial ‘hawk’ alarm calls of passerines provide a textbook example of signal design because many species have converged on a design that thwarts eavesdropping by hawks, and call similarity might therefore allow recognition. We measured the response of fairy-wrens ( Malurus cyaneus ) to playback of acoustically similar scrubwren ( Sericornis frontalis ) aerial alarm calls. First, if call similarity prompts escape independent of learning, then fairy-wrens should flee to playback of scrubwren calls outside their geographical range. However, fairy-wrens fled only in sympatry. Second, if call similarity is necessary for learning heterospecific calls, then fairy-wrens should not respond to sympatric species with different calls. We found, on the contrary, that fairy-wrens fled to the very different aerial alarm calls of a honeyeater ( Phylidonyris novaehollandiae ). Furthermore, response to the honeyeater depended on the specific structure of the call, not acoustic similarity. Overall, call similarity was neither sufficient nor necessary for interspecific recognition, implying learning is essential in the complex task of sifting the acoustic world for cues about danger.

Acoustic Features of Rhesus Vocalizations and Their Representation in the Ventrolateral Prefrontal Cortex

2007 ◽  
Vol 97 (2) ◽  
pp. 1470-1484 ◽  
Author(s):  
Yale E. Cohen ◽  
Frédéric Theunissen ◽  
Brian E. Russ ◽  
Patrick Gill
Keyword(s):  
Prefrontal Cortex ◽  
Acoustic Properties ◽  
Acoustic Features ◽  
Ventrolateral Prefrontal Cortex ◽  
Communication Signals ◽  
First Order ◽  
Natural Stimuli ◽  
Spectrotemporal Receptive Field ◽  
Auditory Objects

Communication is one of the fundamental components of both human and nonhuman animal behavior. Auditory communication signals (i.e., vocalizations) are especially important in the socioecology of several species of nonhuman primates such as rhesus monkeys. In rhesus, the ventrolateral prefrontal cortex (vPFC) is thought to be part of a circuit involved in representing vocalizations and other auditory objects. To further our understanding of the role of the vPFC in processing vocalizations, we characterized the spectrotemporal features of rhesus vocalizations, compared these features with other classes of natural stimuli, and then related the rhesus-vocalization acoustic features to neural activity. We found that the range of these spectrotemporal features was similar to that found in other ensembles of natural stimuli, including human speech, and identified the subspace of these features that would be particularly informative to discriminate between different vocalizations. In a first neural study, however, we found that the tuning properties of vPFC neurons did not emphasize these particularly informative spectrotemporal features. In a second neural study, we found that a first-order linear model (the spectrotemporal receptive field) is not a good predictor of vPFC activity. The results of these two neural studies are consistent with the hypothesis that the vPFC is not involved in coding the first-order acoustic properties of a stimulus but is involved in processing the higher-order information needed to form representations of auditory objects.

scholarly journals Bright birds are cautious: seasonally conspicuous plumage prompts risk avoidance by male superb fairy-wrens

2017 ◽  
Vol 284 (1857) ◽  
pp. 20170446 ◽  
Author(s):  
Alexandra McQueen ◽  
Annalise C. Naimo ◽  
Niki Teunissen ◽  
Robert D. Magrath ◽  
Kaspar Delhey ◽  
...  
Keyword(s):  
Colour Change ◽  
Alarm Call ◽  
Seasonal Effects ◽  
Alarm Calls ◽  
Risk Avoidance ◽  
Risk Of Predation ◽  
Individual Effects ◽  
Group Members ◽  
Time Of Year ◽  
Malurus Cyaneus

Increased predation risk is considered a cost of having conspicuous colours, affecting the anti-predator behaviour of colourful animals. However, this is difficult to test, as individual factors often covary with colour and behaviour. We used alarm call playback and behavioural observations to assess whether individual birds adjust their response to risk according to their plumage colour. Male superb fairy-wrens ( Malurus cyaneus ) change from a dull brown to conspicuous blue plumage each year, allowing the behaviour of different coloured birds to be compared while controlling for within-individual effects. Because the timing of colour change varies among males, blue and brown birds can also be compared at the same time of year, controlling for seasonal effects on behaviour. While blue, fairy-wrens fled more often in response to alarm calls, and took longer to emerge from cover. Blue fairy-wrens also spent more time foraging in cover and being vigilant. Group members appeared to benefit from the presence of blue males, as they reduced their response to alarms, and allocated less time to sentinel behaviour when a blue male was close by. We suggest that fairy-wrens perceive themselves to be at a higher risk of predation while in conspicuous plumage and adjust their behaviour accordingly.

scholarly journals A micro-geography of fear: learning to eavesdrop on alarm calls of neighbouring heterospecifics

2011 ◽  
Vol 279 (1730) ◽  
pp. 902-909 ◽  
Author(s):  
Robert D. Magrath ◽  
Thomas H. Bennett
Keyword(s):  
Community Composition ◽  
Geographical Variation ◽  
Relevant Information ◽  
Dispersal Distance ◽  
Fear Learning ◽  
Alarm Calls ◽  
Acoustic Features ◽  
Noisy Miner ◽  
Manorina Melanocephala ◽  
Malurus Cyaneus

Many vertebrates eavesdrop on alarm calls of other species, which is a remarkable ability, given geographical variation in community composition and call diversity within and among species. We used micro-geographical variation in community composition to test whether individuals recognize heterospecific alarm calls by: (i) responding to acoustic features shared among alarm calls; (ii) having innate responses to particular heterospecific calls; or (iii) learning specific alarm calls. We found that superb fairy-wrens ( Malurus cyaneus ) fled to cover to playback of noisy miner ( Manorina melanocephala ) aerial predator alarm calls only in locations where miners were present, suggesting that learning rather than acoustic structure determines response. Sites with and without miners were well within the dispersal distance of fairy-wrens, and philopatric males and dispersing females showed the same pattern, so that local genetic adaptation is extremely unlikely. Furthermore, where miners were present, fairy-wrens responded appropriately to different miner calls, implying eavesdropping on their signalling system rather than fleeing from miners themselves. Learned eavesdropping on alarm calls enables individuals to harvest ecologically relevant information from heterospecifics on an astonishingly fine spatial scale. Such phenotypic plasticity is valuable in a changing world, where individuals can be exposed to new species.

The role of alarm signal duration as a cue for alarm validity

2007 ◽  
Vol 38 (2) ◽  
pp. 191-199 ◽  
Author(s):  
James P. Bliss ◽  
Corey K. Fallon ◽  
Nicolae Nica
Keyword(s):  
Signal Duration ◽  
Alarm Signal

scholarly journals The role of introductory alarm calls for song discrimination in Ficedula flycatchers

2021 ◽  
Vol 177 ◽  
pp. 241-251
Author(s):  
Louis Bliard ◽  
Anna Qvarnström ◽  
David Wheatcroft
Keyword(s):  
Alarm Calls ◽  
Song Discrimination

Role of Acoustic Properties in Biomedical Active Noise Control

2020 ◽  
Vol 9 (1) ◽  
pp. 48-60
Author(s):  
Sajil C. K. ◽  
Achuthsankar S. Nair
Keyword(s):  
Numerical Simulation ◽  
Biomedical Applications ◽  
Noise Control ◽  
Active Noise Control ◽  
Acoustic Properties ◽  
Reflection Coefficients ◽  
Sensors And Actuators ◽  
Active Noise ◽  
Source Signal

Active noise control (ANC) systems are tailored for user-specific scenarios which are required in biomedical applications due to the physical restrictions in the placement of sensors and actuators. This study examines the role of spectral flatness of acoustic channels and room reflection coefficients in ANC performance. Each room has a unique characteristic response in transforming a source signal. By employing preliminary measurements and numerical simulation, the authors show that improved noise control is possible by optimizing room reverberation and spectral flatness of the secondary acoustic channel. This result has potential application in improving existing ANC systems in biomedical applications like fMRI.

scholarly journals Heterospecific alarm-call recognition in two warbler hosts of common cuckoos

2019 ◽  
Vol 22 (6) ◽  
pp. 1149-1157 ◽  
Author(s):  
Jiangping Yu ◽  
Hailin Lu ◽  
Wei Sun ◽  
Wei Liang ◽  
Haitao Wang ◽  
...  
Keyword(s):  
Alarm Call ◽  
Alarm Calls ◽  
Reed Warbler ◽  
Cuculus Canorus ◽  
Common Cuckoo ◽  
Playback Experiments ◽  
Call Recognition ◽  
Accipiter Nisus ◽  
Main Host ◽  
The Common

Abstract Species facing similar selection pressures should recognize heterospecific alarm signals. However, no study has so far examined heterospecific alarm-call recognition in response to parasitism by cuckoos. In this study, we tested whether two sympatric host species of the common cuckoo Cuculus canorus, Oriental reed warbler Acrocephalus orientalis (ORW, main host), and black-browed reed warbler Acrocephalus bistrigiceps (BRW, rare host), could recognize each other’s alarm calls in response to cuckoos. Dummies of common cuckoo (parasite) and Eurasian sparrowhawk Accipiter nisus (predator) were used to induce and record alarm calls of the two warbler species, respectively. In the conspecific alarm-call playback experiments, ORW responded more strongly to cuckoo alarm calls than to sparrowhawk alarm calls, while BRW responded less strongly to cuckoo alarm calls than to sparrowhawk alarm calls. In the heterospecific alarm-call playback experiments, both ORW and BRW responded less strongly to cuckoo alarm calls than sparrowhawk alarm calls. BRW seemed to learn the association between parasite-related alarm calls of the ORW and the cuckoo by observing the process of ORW attacking cuckoos. In contrast, alarm calls of BRW to cuckoos were rarely recorded in most cases. BRW with low parasite pressure still developed recognition of heterospecific parasite-related alarm call. Unintended receivers in the same community should recognize heterospecific alarm calls precisely to extract valuable information.

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