02263nas a2200169 4500008004100000245008000041210006900121520163100190653001901821653001701840653001901857653002001876653002301896100002201919700002501941856012701966 2019 eng d00aModeling active sensing reveals echo detection even in large groups of bats0 aModeling active sensing reveals echo detection even in large gro3 a

Active sensing animals perceive their surroundings by emitting probes of energy and analyzing how the environment modulates these probes. However, the probes of conspecifics can jam active sensing, which should cause problems for groups of active sensing animals. This problem was termed the cocktail party nightmare for echolocating bats: as bats listen for the faint returning echoes of their loud calls, these echoes will be masked by the loud calls of other close-by bats. Despite this problem, many bats echolocate in groups and roost socially. Here, we present a biologically parametrized framework to quantify echo detection in groups. Incorporating properties of echolocation, psychoacoustics, acoustics, and group flight, we quantify how well bats flying in groups can detect each other despite jamming. A focal bat in the center of a group can detect neighbors in group sizes of up to 100 bats. With increasing group size, fewer and only the closest and frontal neighbors are detected. Neighbor detection is improved by longer call intervals, shorter call durations, denser groups, and more variable flight and sonar beam directions. Our results provide a quantification of the sensory input of echolocating bats in collective group flight, such as mating swarms or emergences. Our results further generate predictions on the sensory strategies bats may use to reduce jamming in the cocktail party nightmare. Lastly, we suggest that the spatially limited sensory field of echolocators leads to limited interactions within a group, so that collective behavior is achieved by following only nearest neighbors.

10aactive sensing10abioacoustics10agroup behavior10apsychoacoustics10asonar interference1 aBeleyur, Thejasvi1 aGoerlitz, Holger, R. uhttp://www.pnas.org/lookup/doi/10.1073/pnas.1821722116https://syndication.highwire.org/content/doi/10.1073/pnas.182172211603094nas a2200397 4500008004100000022001300041245005700054210005700111260001600168520180000184653000801984653002301992653001702015653001302032653000802045653002102053653001502074653001702089100002202106700002202128700001802150700001902168700001602187700002502203700003402228700002402262700002302286700001602309700001802325700002602343700002602369700002602395700002502421700001702446856023302463 2018 eng d a0960982200aResource Ephemerality Drives Social Foraging in Bats0 aResource Ephemerality Drives Social Foraging in Bats cJan-11-20183 a

Observations of animals feeding in aggregations are often interpreted as events of social foraging, but it can be difficult to determine whether the animals arrived at the foraging sites after collective search [1, 2, 3, 4] or whether they found the sites by following a leader [5, 6] or even independently, aggregating as an artifact of food availability [7, 8]. Distinguishing between these explanations is important, because functionally, they might have very different consequences. In the first case, the animals could benefit from the presence of conspecifics, whereas in the second and third, they often suffer from increased competition [3, 9, 10, 11, 12, 13]. Using novel miniature sensors, we recorded GPS tracks and audio of five species of bats, monitoring their movement and interactions with conspecifics, which could be inferred from the audio recordings. We examined the hypothesis that food distribution plays a key role in determining social foraging patterns [14, 15, 16]. Specifically, this hypothesis predicts that searching for an ephemeral resource (whose distribution in time or space is hard to predict) is more likely to favor social foraging [10, 13, 14, 15] than searching for a predictable resource. The movement and social interactions differed between bats foraging on ephemeral versus predictable resources. Ephemeral species changed foraging sites and showed large temporal variation nightly. They aggregated with conspecifics as was supported by playback experiments and computer simulations. In contrast, predictable species were never observed near conspecifics and showed high spatial fidelity to the same foraging sites over multiple nights. Our results suggest that resource (un)predictability influences the costs and benefits of social foraging.

10abat10abehavioral ecology10aecholocation10aforaging10aGPS10amovement ecology10anavigation10asociobiology1 aEgert-Berg, Katya1 aHurme, Edward, R.1 aGreif, Stefan1 aGoldstein, Aya1 aHarten, Lee1 aM., Luis, Gerardo He1 aFlores-Martínez, José, Juan1 aValdés, Andrea, T.1 aJohnston, Dave, S.1 aEitan, Ofri1 aBorissov, Ivo1 aShipley, Jeremy, Ryan1 aMedellin, Rodrigo, A.1 aWilkinson, Gerald, S.1 aGoerlitz, Holger, R.1 aYovel, Yossi uhttps://linkinghub.elsevier.com/retrieve/pii/S0960982218312909https://api.elsevier.com/content/article/PII:S0960982218312909?httpAccept=text/xmlhttps://api.elsevier.com/content/article/PII:S0960982218312909?httpAccept=text/plain01828nas a2200181 4500008004100000022001300041245007600054210006900130260001600199300001600215490000700231520124800238100002501486700002901511700002201540700001801562856006601580 2010 eng d a0960982200aAn Aerial-Hawking Bat Uses Stealth Echolocation to Counter Moth Hearing0 aAerialHawking Bat Uses Stealth Echolocation to Counter Moth Hear cJan-09-2010 a1568 - 15720 v203 a

Ears evolved in many nocturnal insects, including some moths, to detect bat echolocation calls and evade capture [1, 2]. Although there is evidence that some bats emit echolocation calls that are inconspicuous to eared moths, it is difficult to determine whether this was an adaptation to moth hearing or originally evolved for a different purpose [2, 3]. Aerial-hawking bats generally emit high-amplitude echolocation calls to maximize detection range [4, 5]. Here we present the first example of an echolocation counterstrategy to overcome prey hearing at the cost of reduced detection distance. We combined comparative bat flight-path tracking and moth neurophysiology with fecal DNA analysis to show that the barbastelle, Barbastella barbastellus, emits calls that are 10 to 100 times lower in amplitude than those of other aerial-hawking bats, remains undetected by moths until close, and captures mainly eared moths. Model calculations demonstrate that only bats emitting such low-amplitude calls hear moth echoes before their calls are conspicuous to moths. This stealth echolocation allows the barbastelle to exploit food resources that are difficult to catch for other aerial-hawking bats emitting calls of greater amplitude.

1 aGoerlitz, Holger, R.1 aHofstede, Hannah, M. ter1 aZeale, Matt, R.K.1 aJones, Gareth uhttp://linkinghub.elsevier.com/retrieve/pii/S096098221000991702082nas a2200229 4500008004100000022001400041245007400055210006900129260001600198300001600214490000700230520136400237653002301601653001601624653003101640653002001671100002901691700002501720700003301745700001901778856005501797 2011 eng d a0028-104200aTympanal mechanics and neural responses in the ears of a noctuid moth0 aTympanal mechanics and neural responses in the ears of a noctuid cJan-12-2011 a1057 - 10610 v983 a

Ears evolved in many groups of moths to detect the echolocation calls of predatory bats. Although the neurophysiology of bat detection has been intensively studied in moths for decades, the relationship between sound-induced movement of the noctuid tympanic membrane and action potentials in the auditory sensory cells (A1 and A2) has received little attention. Using laser Doppler vibrometry, we measured the velocity and displacement of the tympanum in response to pure tone pulses for moths that were intact or prepared for neural recording. When recording from the auditory nerve, the displacement of the tympanum at the neural threshold remained constant across frequencies, whereas velocity varied with frequency. This suggests that the key biophysical parameter for triggering action potentials in the sensory cells of noctuid moths is tympanum displacement, not velocity. The validity of studies on the neurophysiology of moth hearing rests on the assumption that the dissection and recording procedures do not affect the biomechanics of the ear. There were no consistent differences in tympanal velocity or displacement when moths were intact or prepared for neural recordings for sound levels close to neural threshold, indicating that this and other neurophysiological studies provide good estimates of what intact moths hear at threshold.

10aauditory threshold10aLepidoptera10amoth auditory biomechanics10aneurophysiology1 aHofstede, Hannah, M. ter1 aGoerlitz, Holger, R.1 aMontealegre-Zapata, Fernando1 aRobert, Daniel uhttp://link.springer.com/10.1007/s00114-011-0851-702456nas a2200229 4500008004100000245007100041210006900112260001600181490000600197520170600203653002701909653001801936653001701954653001701971653003201988653003202020653001702052100003102069700002502100700002402125856007702149 2013 eng d00aInterspecific acoustic recognition in two European bat communities0 aInterspecific acoustic recognition in two European bat communiti cJan-01-20130 v43 a

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.

10aacoustic communication10aeavesdropping10aecholocation10afeeding buzz10ainterspecific communication10aintraspecific communication10asearch calls1 aDorado-Correa, Adriana, M.1 aGoerlitz, Holger, R.1 aSiemers, Björn, M. uhttp://journal.frontiersin.org/article/10.3389/fphys.2013.00192/abstract03035nas a2200289 4500008004100000245010500041210006900146260001600215300001400231490000700245520213200252653002302384653000902407653002402416653002002440653002502460100002502485700002502510700002602535700002202561700001802583700002602601700002402627700001802651700002302669856005302692 2014 eng d00aTrophic niche flexibility in Glossophaga soricina: how a nectar seeker sneaks an insect snack0 aTrophic niche flexibility in iGlossophaga soricinai how a nectar cJan-06-2014 a632 - 6410 v283 a

Omnivory enables animals to fill more than one trophic niche, providing access to a wider variety of food resources with potentially higher nutrient value, particularly when resources become scarce. Animals can achieve omnivory using different strategies, for example opportunistic foraging, or switching between multiple trophic niches.

The Neotropical bat Glossophaga soricina (Pallas, 1766) is a common and widespread species known for nectar feeding, but it also eats fruit and insects. Approaching stationary objects (flowers and fruits) or moving objects (insects) poses different sensory tasks and should require different echolocation behaviours. Here we tested the contrasting hypothesis that G. soricina can approach both stationary and moving objects using the same echolocation behaviour, thus feeding at different trophic levels by a single sensory mechanism.

Using DNA barcoding, we demonstrate that G. soricina eats beetles (Coleoptera), flies (Diptera) and noctuid moths with bat-detecting ears. Laboratory observations show that G. soricina actively hunts for prey so insect consumption does not appear to be opportunistic. After capture, individuals consumed prey while perched and manipulated them with jaw, thumb, wrist and wing movements, but food handling was longer and chewing rate slower than in obligate insectivores.

In contrast to most insectivorous bats, the echolocation calls of G. soricina are of high frequency and low intensity, and G. soricina did not produce feeding buzzes when approaching insects. An acoustic model of detection distances shows that its low-intensity calls fail to trigger the auditory neurons of eared moths, allowing G. soricina to overcome auditory prey defences.

Individuals achieved niche flexibility using a unique but generalist behavioural approach rather than employing two different specialist methods. Our findings provide a novel insight into the functional mechanisms of insect capture in G. soricina and highlight the importance of considering niche flexibility in classifying trophic links in ecological communities.

10aacoustic modelling10abats10amolecular scatology10apredator–prey10astealth echolocation1 aClare, Elizabeth, L.1 aGoerlitz, Holger, R.1 aDrapeau, Violaine, A.1 aAdams, Amanda, M.1 aNagel, Juliet1 aDumont, Elizabeth, R.1 aHebert, Paul, D. N.1 aFenton, Brock1 aKonarzewski, Marek uhttp://doi.wiley.com/10.1111/fec.2014.28.issue-301987nas a2200157 4500008004100000245010400041210006900145260001600214490000600230520146900236100001701705700002501722700001801747700001901765856004501784 2016 eng d00aLinking the sender to the receiver: vocal adjustments by bats to maintain signal detection in noise0 aLinking the sender to the receiver vocal adjustments by bats to  cJan-11-20160 v53 a

Short-term adjustments of signal characteristics allow animals to maintain reliable communication in noise. Noise-dependent vocal plasticity often involves simultaneous changes in multiple parameters. Here, we quanti ed for the  rst time the relative contributions of signal amplitude, duration,
and redundancy for improving signal detectability in noise. To this end, we used a combination of behavioural experiments on pale spear-nosed bats (Phyllostomus discolor) and signal detection models. In response to increasing noise levels, all bats raised the amplitude of their echolocation calls by 1.8–7.9 dB (the Lombard e ect). Bats also increased signal duration by 13%–85%, corresponding to an increase in detectability of 1.0–5.3 dB. Finally, in some noise conditions, bats increased signal redundancy by producing more call groups. Assuming optimal cognitive integration, this could result in a further detectability improvement by up to 4 dB. Our data show that while the main improvement in signal detectability was due to the Lombard e ect, increasing signal duration and redundancy can also contribute markedly to improving signal detectability. Overall, our  ndings demonstrate that
the observed adjustments of signal parameters in noise are matched to how these parameters are processed in the receiver’s sensory system, thereby facilitating signal transmission in  uctuating environments.

1 aLuo, Jinhong1 aGoerlitz, Holger, R.1 aBrumm, Henrik1 aWiegrebe, Lutz uhttp://www.nature.com/articles/srep18556