Echolocation at high intensity imposes metabolic costs on flying bats

Currie, Shannon E.; Boonman, Arjan; Troxell, Sara A; Yovel, Yossi; Voigt, Christian C.

doi:10.1038/s41559-020-1249-8

Cited by 46 publications

(41 citation statements)

References 33 publications

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“…This raises the question of why bats opt for such weak echoes spanning a relatively low echo dynamic range if they can increase echo levels for auditory processing by producing louder calls. At long ranges, call intensity may already be maximized (30), and the low echo strength is a consequence of small prey items and high absorption of ultrasound in air. However, as wild bats approach their prey, they produce calls that are well below their maximum intensity, resulting in extremely low echo levels close to the hearing threshold.…”

Section: Weak Prey Echoes In a Simplified Auditory Scenementioning

confidence: 99%

Hunting bats adjust their echolocation to receive weak prey echoes for clutter reduction

et al. 2021

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How animals extract information from their surroundings to guide motor patterns is central to their survival. Here, we use echo-recording tags to show how wild hunting bats adjust their sensory strategies to their prey and natural environment. When searching, bats maximize the chances of detecting small prey by using large sensory volumes. During prey pursuit, they trade spatial for temporal information by reducing sensory volumes while increasing update rate and redundancy of their sensory scenes. These adjustments lead to very weak prey echoes that bats protect from interference by segregating prey sensory streams from the background using a combination of fast-acting sensory and motor strategies. Counterintuitively, these weak sensory scenes allow bats to be efficient hunters close to background clutter broadening the niches available to hunt for insects.

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Section: Weak Prey Echoes In a Simplified Auditory Scenementioning

confidence: 99%

Hunting bats adjust their echolocation to receive weak prey echoes for clutter reduction

et al. 2021

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“…This study contributes to our understanding of how animals adjust the acquisition of personal information to deal with the constraints they face when sensing the world sequentially through sound. Our results show that they increase information quantity (call rate) only to a level as required by the task but not above that, likely to minimize the costs required for vocal production (Elemans et al, 2011; Currie et al 2020) and sensory analysis (Laughlin et al, 1998; Niven & Laughlin, 2008) at high information update rates. In addition, by flexibly adjusting call features, such as duration and frequency, bats also adapt the quality of the acquired information.…”

Section: Discussionmentioning

confidence: 67%

“…However, long-duration calls increase the probability that echoes reflected off close-by objects overlap in time with the outgoing call (‘forward masking’), which can impair object detection and evaluation (Schnitzler et al, 2003). The same extension of detection distance can be achieved by increasing call amplitude, yet further increasing the amplitude of high-amplitude calls comes at a disproportionately high energetic costs (Currie et al, 2020). Also, high call amplitudes would result in a large number of ‘uninformative’ echoes in cluttered environments, which could distract from relevant echoes and challenge sensory processing (Wahlberg & Surlykke, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…The most extreme case occurs when approaching flying prey, where aerial-hawking bats emit a characteristic call sequence with extremely high call rates, the so-called feeding (or final / terminal) buzz, right before capture (Griffin, 1958; Kalko & Schnitzler, 1989; Lewanzik et al, 2019; Ratcliffe, Elemans, Jakobsen, & Surlykke, 2013). However, high call rates might be energetically expensive especially for bats calling at high amplitudes (Currie, Boonman, Troxell, Yovel, & Voigt, 2020). High call rates can also cause call-echo ambiguity and thus impair ranging and navigation, when echoes of a call return only after the next call has been emitted (Beetz, Kössl, & Hechavarría, 2019; Moss, Chiu, & Surlykke, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Task-dependent vocal adjustments to optimize biosonar-based information acquisition

Lewanzik

Goerlitz

2020

Preprint

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Animals need to acquire adequate and sufficient information to guide movements, yet information acquisition and processing is costly. Animals thus face a trade-off between gathering too little and too much information and, accordingly, actively adapt sensory input through motor control. Echolocating animals provide the unique opportunity to study the dynamics of adaptive sensing in naturally behaving animals without interference, since every change in the outgoing echolocation signal directly affects information acquisition and the perception of the dynamic acoustic scene. Here we investigated the flexibility with which bats dynamically adapt information acquisition depending on a task. We recorded the echolocation signals of wild-caught Western barbastelle bats (Barbastella barbastellus) while drinking on the wing, flying through an opening, landing on a wall, and capturing prey. We show that the echolocation signal sequences during target approach differed in a task-dependent manner; bats started target approach earlier and increased information update rate more when the task became increasingly difficult, and bats also adjusted dynamics of call duration shortening and peak frequency shifts accordingly. We provide insights into how echolocating animals deal with the constraints they face when sequentially sampling the world through sound by adjusting acoustic information flow in a highly dynamic manner. Our results further highlight the paramount importance of high behavioural flexibility for acquiring information.Summary statementHaving the right information for a specific job is crucial. Echolocating bats flexibly and independently adjust different call parameters to match the sensory-motor challenges of four different tasks.

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“…Linking individual variation in acoustic exploration to the ability of bats to quickly detect and respond to novelty on a wider spatial scale, or a comparative investigation of bat populations living along a gradient of habitat stability, would be exciting next steps. Furthermore, a more intense use of an active sensory system, such as echolocation, is not necessarily without energetic costs 62 , so an examination of the potential costs linked to more thorough exploration in bats would likewise be insightful.…”

Section: Discussionmentioning

confidence: 99%

In situnovel environment assay reveals acoustic exploration as a repeatable behavioral response in migratory bats

Schabacker

Lindecke

Rizzi

et al. 2020

Preprint

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Integrating information on species-specific sensory perception together with spatial activity provides a high-resolution understanding of how animals explore environments, yet frequently used exploration assays commonly ignore sensory acquisition as a measure for exploration. Echolocation is an active sensing system used by hundreds of mammal species, primarily bats. As echolocation call activity can be reliably quantified, bats present an excellent animal model to investigate intra-specific variation in environmental cue sampling. Here, we developed an in situ roost-like novel environment assay for tree-cave roosting bats. We repeatedly tested 52 individuals of the migratory bat species, Pipistrellus nathusii, across 24 hours, to examine the role of echolocation when crawling through a maze-type arena and test for consistent intra-specific variation in sensory-based exploration. We reveal a strong correlation between echolocation call activity and spatial activity. Moreover, we show that during the exploration of the maze, individuals consistently differed in spatial activity as well as echolocation call activity given their spatial activity, a behavioral response we term ‘acoustic exploration’. Acoustic exploration was correlated with other exploratory behaviors, but not with emergence latency. We here present a relevant new measure for exploration behavior and provide evidence for consistent (short-term) intra-specific variation in the level at which wild bats collect information from a novel environment.

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Echolocation at high intensity imposes metabolic costs on flying bats

Cited by 46 publications

References 33 publications

Hunting bats adjust their echolocation to receive weak prey echoes for clutter reduction

Hunting bats adjust their echolocation to receive weak prey echoes for clutter reduction

Task-dependent vocal adjustments to optimize biosonar-based information acquisition

In situnovel environment assay reveals acoustic exploration as a repeatable behavioral response in migratory bats

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