@article {57571, title = {Acoustic crypsis in communication by North Atlantic right whale mother{\textendash}calf pairs on the calving grounds}, year = {2019}, abstract = {

Mammals with dependent young often rely on cryptic behaviour to avoid detection by potential predators. In the mysticetes, large baleen whales, young calves are known to be vulnerable to direct predation from both shark and orca predators; therefore, it is possible that mother\–calf pairs may show cryptic behaviours to avoid the attention of predators. Baleen whales primarily communicate through low-frequency acoustic signals, which can travel over long ranges. In this study, we explore the potential for acoustic crypsis, a form of cryptic behaviour to avoid predator detection, in North Atlantic right whale mother\–calf pairs. We predicted that mother\– calf pairs would either show reduced calling rates, reduced call amplitude or a combination of these behavioural modifications when compared with other demographic groups in the same habitat. Our results show that right whale mother\–calf pairs have a strong shift in repertoire usage, significantly reducing the number of higher amplitude, long-distance communication signals they produced when compared with juvenile and pregnant whales in the same habitat. These observations show that right whale mother\–calf pairs rely upon acoustic crypsis, potentially to minimize the risk of acoustic eavesdropping by predators.

}, keywords = {acoustic crypsis, baleen whale, eavesdropping, predator avoidance, right whale}, doi = {10.1098/rsbl.2019.0485}, url = {https://royalsocietypublishing.org/doi/10.1098/rsbl.2019.0485}, author = {Parks, Susan E. and Cusano, Dana A. and Sofie M. Van Parijs and Nowacek, Douglas P.} } @article {57565, title = {Eavesdropping on a heterospecific alarm call in the giant root-rat (Tachyorytes macrocephalus), an important prey of the Ethiopian wolf (Canis simensis)}, year = {2019}, abstract = {

The giant root-rat of the Bale Mountains, Ethiopia has been reported to have a mutualistic relationship with a passerine, which involves eavesdropping on its alarm call. We tested this in a field playback experiment. Besides the alarm call, we included two sounds potentially acting as alarm cues and one as a control. Little reaction of root-rats was detected to the bird alarm call. However, intensive reaction was detected to an alarm call of the black-clawed brush-furred rat, a social rodent often occupying root-rats\’ burrows. This result is understandable given the two rodents have the same principal predator, the Ethiopian wolf.

}, keywords = {Afroalpine, Alarm, Anti-predator, eavesdropping, Mutualism, Wing whistle}, doi = {10.1007/s10164-019-00618-1}, url = {http://link.springer.com/10.1007/s10164-019-00618-1}, author = {Hrouzkov{\'a}, Ema and Bernasov{\'a}, Eli{\v s}ka and {\v S}kl{\'\i}ba, Jan} } @article {57386, title = {Dueling frogs: do male green tree frogs (Hyla cinerea) eavesdrop on and assess nearby calling competitors?}, year = {2019}, abstract = {

Individuals produce advertisement signals with intended purposes and targets. However, these signals can be received by \“eavesdroppers,\” who may extract information from them and alter their behavior according to the extracted information. In anuran systems, males congregate at breeding sites to produce advertisement calls to attract receptive females and fend off rival males. Both sexes directly assess these calls in dyadic encounters and make decisions based on the call\’s characteristics, e.g., frequency. What is unknown is whether bystander males eavesdrop on these same calls to inform their future competitive decisions. Here, we examined whether male green tree frogs (Hyla cinerea) eavesdrop on competing males, assess their competitor\’s call frequency, and respond accordingly. We exposed males to playbacks of two competing males that varied in call frequency\—high, average, low\—and quantified latency to call, time spent calling, and number of calling bouts. We found that males had reduced latency to call and called more when eavesdropping low-frequency competition, but not average or high-frequency competition. Focal male size also influenced how they responded, with larger males being more responsive than smaller males. Our results indicate that male green tree frogs are capable of eavesdropping on nearby male calls and produce behavioral responses accordingly. Further, it appears males are able to alternate between assessment strategies dependent upon the frequency of the eavesdropped competition. These findings indicate that males not only directly assess an opponent\’s call in dyadic encounters, but also indirectly through eavesdropping.

}, keywords = {competition, eavesdropping, Green tree frogs, Hyla cinerea, Male call assessment}, doi = {10.1007/s00265-018-2632-1}, url = {http://link.springer.com/10.1007/s00265-018-2632-1}, author = {Garcia, Mark J. and Cronin, Andrew and Bowling, Tyler and Bushera, Hakeem and Hunter, Kimberly L. and Taylor, Ryan C.} } @article {50498, title = {To seek or speak? Dual function of an acoustic signal limits its versatility in communication}, journal = {Animal Behaviour}, volume = {127}, year = {2017}, month = {Jan-05-2017}, pages = {135 - 152}, abstract = {

The perception of different attributes of conspecifics is an integral part of intraspecific communication. It can facilitate the recognition of interaction partners or the assessment of potential mates. Acoustic signals can encode fine-scaled information through the interplay of acoustic variability and specificity. A reliable vocal signature is both unique within a class and variable between classes. Therefore, acoustic complexity might be associated with the number of classes to be discriminated. We investigated the assumption that limitations to signal design may affect the communicative functionality of a signal. To do so, we chose a signal with potentially dual functionality which may therefore display such limitations. In bats, echolocation is used primarily for foraging and orientation but there is increasing support for its additional role in communication. An acoustic analysis of echolocation pulses of the bat Rhinolophus clivosus confirmed sex and individual vocal signatures in echolocation pulses. A habituation\–dishabituation playback experiment suggested that bats perceived these signatures because listening bats clearly discriminated between the sexes (two classes) and between individuals (representatives of a multiclass category), although to different degrees. The simple acoustic structure of these vocalizations provides sufficient specificity for sex discrimination but has limitations for individual discrimination because pulse parameters of individuals increasingly overlapped with increasing group size. We conclude that selection for the primary function of echolocation restricts the acoustic space available for communication. However, we frequently observed echolocation pulses with conspicuous structural modifications. Statistical analyses revealed that these vocalizations yielded increased individual distinctiveness. Such added systematic variation may indicate a communicative function and perhaps a signalling intent of the emitter, although the latter has yet to be tested. The findings suggest that the required specificity for effective communication could be obtained through modification of echolocation variants when adaptations for orientation and foraging constrain the evolution of complex communication signatures.

}, keywords = {acoustic communication, bats, co-option, constraints, eavesdropping, echolocation, habituation{\textendash}dishabituation playback, individual and sex discrimination, signal design, vocal signatures}, issn = {00033472}, doi = {10.1016/j.anbehav.2017.03.005}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0003347217300775}, author = {Anna Bastian and David Steve Jacobs} } @article {48149, title = {Interspecific acoustic recognition in two European bat communities}, journal = {Frontiers in Physiology}, volume = {4}, year = {2013}, month = {Jan-01-2013}, abstract = {

Echolocating bats emit echolocation calls for spatial orientation and foraging. These calls are often species-specific and are emitted at high intensity and repetition rate. Therefore, these calls could potentially function in intra- and/or inter-specific bat communication. For example, bats in the field approach playbacks of conspecific feeding buzzes, probably because feeding buzzes indicate an available foraging patch. In captivity, some species of bats recognize and distinguish the echolocation calls of different sympatric species. However, it is still unknown if and how acoustic species-recognition mediates interspecific interactions in the field. Here we aim to understand eavesdropping on bat echolocation calls within and across species boundaries in wild bats. We presented playbacks of conspecific and heterospecific search calls and feeding buzzes to four bat species with different foraging ecologies. The bats were generally more attracted by feeding buzzes than search calls and more by the calls of conspecifics than their heterospecifics. Furthermore, bats showed differential reaction to the calls of the heterospecifics. In particular, \<i\>Myotis capaccinii\</i\> reacted equally to the feeding buzzes of conspecifics and to ecologically more similar heterospecifics. Our results confirm eavesdropping on feeding buzzes at the intraspecific level in wild bats and provide the first experimental quantification of potential eavesdropping in European bats at the interspecific level. Our data support the hypothesis that bat echolocation calls have a communicative potential that allows interspecific, and potentially intraspecific, eavesdropping in the wild.

}, keywords = {acoustic communication, eavesdropping, echolocation, feeding buzz, interspecific communication, intraspecific communication, search calls}, doi = {10.3389/fphys.2013.00192}, url = {http://journal.frontiersin.org/article/10.3389/fphys.2013.00192/abstract}, author = {Dorado-Correa, Adriana M. and Goerlitz, Holger R. and Siemers, Bj{\"o}rn M.} } @article {47908, title = {Behavioural specialization among populations of the acoustically orienting parasitoid fly Ormia ochracea utilizing different cricket species as hosts}, journal = {Animal Behaviour}, volume = {73}, year = {2007}, month = {Jan-01-2007}, pages = {99 - 104}, abstract = {

Tightly coupled evolutionary associations between parasites and their hosts are well known. What is less well characterized is the behavioural specialization of parasites that exploit different hosts in different parts of the parasite\’s geographical range. Here we examine behavioural specialization among populations of a parasitoid fly, Ormia ochracea, that exploit different host species of crickets in different parts of the fly\’s range. We conducted a field experiment to compare phonotactic attraction of flies from Florida, Texas, California and Hawaii (U.S.A.) to the songs of their local host species of cricket versus their attraction to the songs of species of crickets utilized as hosts elsewhere within the flies\’ range. We found strong behavioural specialization of fly populations, with preferential phonotaxis towards the song of the local host species of cricket. These results suggest strong behavioural specialization of flies, but that specialization does not constrain or preclude the rapid adoption of novel hosts.

}, keywords = {acoustic communication, behavioural specialization, diptera-orthoptera coevolution, eavesdropping, host selection, Ormia ochracea, parasitoid fly}, issn = {00033472}, doi = {10.1016/j.anbehav.2006.07.005}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0003347206003939}, author = {Gray, David A. and Banuelos, Christina and Sean E. Walker and William H. Cade and Zuk, Marlene} } @article {47320, title = {To seek or speak? Dual function of an acoustic signal limits its versatility in communication}, journal = {Animal Behaviour}, volume = {127}, year = {2017}, month = {Jan-05-2017}, pages = {135 - 152}, abstract = {

The perception of different attributes of conspecifics is an integral part of intraspecific communication. It can facilitate the recognition of interaction partners or the assessment of potential mates. Acoustic signals can encode fine-scaled information through the interplay of acoustic variability and specificity. A reliable vocal signature is both unique within a class and variable between classes. Therefore, acoustic complexity might be associated with the number of classes to be discriminated. We investigated the assumption that limitations to signal design may affect the communicative functionality of a signal. To do so, we chose a signal with potentially dual functionality which may therefore display such limitations. In bats, echolocation is used primarily for foraging and orientation but there is increasing support for its additional role in communication. An acoustic analysis of echolocation pulses of the bat Rhinolophus clivosus confirmed sex and individual vocal signatures in echolocation pulses. A habituation\–dishabituation playback experiment suggested that bats perceived these signatures because listening bats clearly discriminated between the sexes (two classes) and between individuals (representatives of a multiclass category), although to different degrees. The simple acoustic structure of these vocalizations provides sufficient specificity for sex discrimination but has limitations for individual discrimination because pulse parameters of individuals increasingly overlapped with increasing group size. We conclude that selection for the primary function of echolocation restricts the acoustic space available for communication. However, we frequently observed echolocation pulses with conspicuous structural modifications. Statistical analyses revealed that these vocalizations yielded increased individual distinctiveness. Such added systematic variation may indicate a communicative function and perhaps a signalling intent of the emitter, although the latter has yet to be tested. The findings suggest that the required specificity for effective communication could be obtained through modification of echolocation variants when adaptations for orientation and foraging constrain the evolution of complex communication signatures.

}, keywords = {acoustic communication, bats, co-option, constraints, eavesdropping, echolocation, habituation{\textendash}dishabituation playback, individual and sex discrimination, signal design, vocal signatures}, issn = {00033472}, doi = {10.1016/j.anbehav.2017.03.005}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0003347217300775}, author = {Anna Bastian and David Steve Jacobs} }