03094nas 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/plain03035nas 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