Trawling bats exploit an echo-acoustic ground effect

Zsebők, Sándor; Kroll, Ferdinand; Heinrich, Melina; Genzel, Daria; Siemers, Björn Martin; Wiegrebe, Lutz

doi:10.3389/fphys.2013.00065

Cited by 17 publications

(19 citation statements)

References 28 publications

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“…The bats were held in captivity for over 6 months before the start of this experiment, and they adapted well to the captive environment. They also participated in other experiments, in which they caught mealworms from the water surface (Zseb€ ok et al, 2013). The bat keeping facility was located away from the roads, and care was taken that bats did not experience any continuous loud noise in captivity.…”

Section: Animals and Housingmentioning

confidence: 99%

How anthropogenic noise affects foraging

Luo

Siemers

Koselj

2015

Global Change Biology

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122

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The influence of human activity on the biosphere is increasing. While direct damage (e.g. habitat destruction) is relatively well understood, many activities affect wildlife in less apparent ways. Here, we investigate how anthropogenic noise impairs foraging, which has direct consequences for animal survival and reproductive success. Noise can disturb foraging via several mechanisms that may operate simultaneously, and thus, their effects could not be disentangled hitherto. We developed a diagnostic framework that can be applied to identify the potential mechanisms of disturbance in any species capable of detecting the noise. We tested this framework using Daubenton's bats, which find prey by echolocation. We found that traffic noise reduced foraging efficiency in most bats. Unexpectedly, this effect was present even if the playback noise did not overlap in frequency with the prey echoes. Neither overlapping noise nor nonoverlapping noise influenced the search effort required for a successful prey capture. Hence, noise did not mask prey echoes or reduce the attention of bats. Instead, noise acted as an aversive stimulus that caused avoidance response, thereby reducing foraging efficiency. We conclude that conservation policies may seriously underestimate numbers of species affected and the multilevel effects on animal fitness, if the mechanisms of disturbance are not considered.

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Section: Animals and Housingmentioning

confidence: 99%

How anthropogenic noise affects foraging

Luo

Siemers

Koselj

2015

Global Change Biology

Self Cite

122

138

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“…Siemers et al (2001Siemers et al ( , 2005 showed that prey above water will become more conspicuous and thereby more easily detected by the acoustic mirror effect. Zsebok et al (2013) demonstrated that not only echo-acoustic prey detection, but also discrimination is optimized by a spatiotemporal integration of direct and indirect reflections from a water surface, termed the echo-acoustic ground effect.…”

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confidence: 99%

Biosonar navigation above water II: exploiting mirror images

Genzel

Hoffmann

Prosch

et al. 2015

Journal of Neurophysiology

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As in vision, acoustic signals can be reflected by a smooth surface creating an acoustic mirror image. Water bodies represent the only naturally occurring horizontal and acoustically smooth surfaces. Echolocating bats flying over smooth water bodies encounter echo-acoustic mirror images of objects above the surface. Here, we combined an electrophysiological approach with a behavioral experimental paradigm to investigate whether bats can exploit echo-acoustic mirror images for navigation and how these mirrorlike echo-acoustic cues are encoded in their auditory cortex. In an obstacle-avoidance task where the obstacles could only be detected via their echo-acoustic mirror images, most bats spontaneously exploited these cues for navigation. Sonar ensonifications along the bats' flight path revealed conspicuous changes of the reflection patterns with slightly increased target strengths at relatively long echo delays corresponding to the longer acoustic paths from the mirrored obstacles. Recordings of cortical spatiotemporal response maps (STRMs) describe the tuning of a unit across the dimensions of elevation and time. The majority of cortical single and multiunits showed a special spatiotemporal pattern of excitatory areas in their STRM indicating a preference for echoes with (relative to the setup dimensions) long delays and, interestingly, from low elevations. This neural preference could effectively encode a reflection pattern as it would be perceived by an echolocating bat detecting an object mirrored from below. The current study provides both behavioral and neurophysiological evidence that echo-acoustic mirror images can be exploited by bats for obstacle avoidance. This capability effectively supports echo-acoustic navigation in highly cluttered natural habitats.

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“…, , Zsebok et al. ). This is one of the reasons why bats mostly capture surface‐feeder fish that frequently break the water surface, rendering them detectable to echolocating bats.…”

Section: Resultsmentioning

confidence: 99%

Ecology and evolutionary biology of fishing bats

Aizpurua

Alberdi

2018

Mammal Review

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A few of the >1300 bat species recognised worldwide are known to consume fish to various extents. However, empirical information about how and how much different bat species capture and consume fish is limited and is probably distorted due to the biases introduced by occasional observations. In this review, we aim to synthesise the knowledge so far generated on fishing bats, in order to 1) assess the incidence of fishing in different bat species; 2) discuss the evolutionary framework and origins of fishing behaviour; and 3) identify the ecological challenges of fishing and review the state of knowledge about kinetic, morphological, sensory, behavioural, and physiological adaptations related to fishing. Fishing bats can be clustered into three groups based on the incidence of fish consumption. Noctilio leporinus is the only species in which fishing is widespread (occurring in most populations) and common (occurring most of the time and carried out by many individuals). Myotis vivesi, Myotis pilosus, and Myotis capaccinii comprise the second group, characterised by exhibiting regular fishing behaviour that is restricted to a limited number of populations. Noctilio albiventris, Myotis daubentonii, and Myotis macropus are classified in a third group, because although the occasional presence of fish traces in faeces has been reported, regular fishing behaviour in the wild has not been confirmed. Fishing was developed independently multiple times in different bat lineages, probably under different selective pressures and ecological scenarios. Nevertheless, all fishing species face similar challenges in terms of detecting, capturing, handling, and metabolising fish, which require specific kinetic, morphological, sensory, behavioural, and physiological adaptations. Both basic information about fishing behaviour in different species and specific knowledge of the biological adaptation are still missing. Thus, in this review we identify gaps in the knowledge and suggest experimental approaches to overcome them.

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Trawling bats exploit an echo-acoustic ground effect

Cited by 17 publications

References 28 publications

How anthropogenic noise affects foraging

How anthropogenic noise affects foraging

Biosonar navigation above water II: exploiting mirror images

Ecology and evolutionary biology of fishing bats

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