Detection of targets colocalized in clutter by big brown bats (<i>Eptesicus fuscus</i>)

Stamper, Sarah A.; Simmons, James A.; DeLong, Caroline M.; Bragg, Rebecca

doi:10.1121/1.2932338

Cited by 5 publications

(5 citation statements)

References 26 publications

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“…Specifically, they question common assumptions, including that wide-band emissions cannot be used for detecting prey within clutter, 5 that prey need to be the first echo-producing structure, 9 and that prey echoes need to be greater than the clutter. 11 Our results also suggest that experiments with bats should include prey having deflectable structures, in addition to compact mealworms that do not have them. In reviewing the literature, we speculate that the induced movement of tethered mealworms in response to bat wing air forces allows their detection in the presence of clutter.…”

Section: Discussionmentioning

confidence: 83%

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Bat wing air pressures may deflect prey structures to provide echo cues for detecting prey in clutter

Kuc

2012

The Journal of the Acoustical Society of America

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Bats have remarkable echolocation capabilities to detect prey in darkness. While it is clear how bats do this for prey that is isolated, moving, or noisy, their ability to find still and quiet prey within clutter has remained a mystery. A video published by the ChiRoPing group shows the gleaning bat Micronycteris microtis capturing a still dragonfly specimen sitting on a leaf surface. While hovering over the dragonfly, the bat's wings exert air forces that cause the dragonfly wings to deflect in synchrony with the bat's wing beats. This paper illustrates that echoes from such deflecting wings vary in both amplitude and time-of-flight, producing robust echo cues that permit prey detection, even when the prey is embedded within clutter. Experiments with a dragonfly specimen mounted on a leaf driven by periodic air puffs produced wing deflections that were sensed with sonar pulses. Results demonstrate that echo variations synchronized with periodic air puffs are easily distinguishable from surrounding clutter, even when clutter produces the first echoes. These results suggest a strategy that bats can employ to detect still and silent prey embedded within cluttered environments.

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Section: Discussionmentioning

confidence: 83%

“…[6][7][8] It is currently viewed that bats using only echolocation to detect prey do so only when prey echoes are sufficiently separated from clutter 9,10 or the prey echoes contain some distinguishable features. 11 This paper suggests that bats can manipulate their environments to expose the presence and location of prey.…”

Section: Introductionmentioning

confidence: 99%

Bat wing air pressures may deflect prey structures to provide echo cues for detecting prey in clutter

Kuc

2012

The Journal of the Acoustical Society of America

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“…Moreover, it encourages us to consider organisms and behaviors that have evolved in environments where the pressures, and potential tradeoffs, between stability and change may be finely balanced. Locomotion is particularly challenging when it is difficult to move (surfaces can be irregular and deformable (Daley and Biewener, 2006;Li et al, 2009;Li et al, 2013), the surrounding fluid can be turbulent and cluttered, or difficult to sense (some highly visual animals navigate in very low light (Warrant and Dacke, 2011)), and others behave in complex auditory (Stamper et al, 2008) or olfactory landscapes. Behaving in such environments can be advantageous to avoid competition, predation, and enable intraspecific interactions.…”

Section: Cockroach Wall Followingmentioning

confidence: 99%

Feedback Control as a Framework for Understanding Tradeoffs in Biology

Cowan

Ankaralı

Dyhr

et al. 2014

Integrative and Comparative Biology

133

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Control theory arose from a need to control synthetic systems. From regulating steam engines to tuning radios to devices capable of autonomous movement, it provided a formal mathematical basis for understanding the role of feedback in the stability (or change) of dynamical systems. It provides a framework for understanding any system with regulation via feedback, including biological ones such as regulatory gene networks, cellular metabolic systems, sensorimotor dynamics of moving animals, and even ecological or evolutionary dynamics of organisms and populations. Here, we focus on four case studies of the sensorimotor dynamics of animals, each of which involves the application of principles from control theory to probe stability and feedback in an organism's response to perturbations. We use examples from aquatic (two behaviors performed by electric fish), terrestrial (following of walls by cockroaches), and aerial environments (flight control by moths) to highlight how one can use control theory to understand the way feedback mechanisms interact with the physical dynamics of animals to determine their stability and response to sensory inputs and perturbations. Each case study is cast as a control problem with sensory input, neural processing, and motor dynamics, the output of which feeds back to the sensory inputs. Collectively, the interaction of these systems in a closed loop determines the behavior of the entire system.

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“…Heinrich et al (2011) found a target strength discrimination threshold of 5 dB at a (virtual) object distance of 114 cm for the bat P. discolor. Stamper et al (2008) measured target strength discrimination thresholds of 1-2 dB at a (real) object distance of 25-34 cm for the bat Eptesicus fuscus. Studies analyzing prey in clutter detection in flight measured increased threshold distances between prey and clutter for the bats to detect prey successfully (Moss et al 2006;Moss and Surlykke 2001).…”

Section: Target Strength Of Echo-acoustic Mirror Imagesmentioning

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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Detection of targets colocalized in clutter by big brown bats (Eptesicus fuscus)

Cited by 5 publications

References 26 publications

Bat wing air pressures may deflect prey structures to provide echo cues for detecting prey in clutter

Bat wing air pressures may deflect prey structures to provide echo cues for detecting prey in clutter

Feedback Control as a Framework for Understanding Tradeoffs in Biology

Biosonar navigation above water II: exploiting mirror images

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