Species-specific strategies increase unpredictability of escape flight in eared moths

Huegel, Theresa; Goerlitz, Holger R.

doi:10.1101/485698

Cited by 4 publications

(4 citation statements)

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“…To our surprise, we found large variations in the relative bat-prey approach speeds [1.4 to 4.9 m/s (95% data range), derived from the slopes of the echo streams; fig. S1], indicating that bats used nonstereotypic motor approaches when tracking prey with potentially different evasive strategies ( 20 ). Some of the typical aerial prey types targeted by greater mouse-eared bats belong in families with ears (e.g., Geometridae , Notodontidae , and Noctuidae ), allowing these moths to perform evasive maneuvers.…”

Section: Resultsmentioning

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: Resultsmentioning

confidence: 99%

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

et al. 2021

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“…It is important to note, though, that our study design tested the effect of light only indirectly, by testing the effect of sound on light‐mediated moth captures, not the effect of light on sound‐mediated evasive flight. In addition, showing no effect is difficult and is complicated by the natural variability of moth behavior (Hügel & Goerlitz 2019), potentially complicating simple answers. If increasing artificial light at night suppresses both negative phonotaxis and last‐ditch maneuvers, moths are not only unable to escape nearby predators, but also unable to avoid distant predators by flying away.…”

Section: Discussionmentioning

confidence: 99%

Light might suppress both types of sound‐evoked antipredator flight in moths

Hügel

Goerlitz

2020

Ecology and Evolution

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Urbanization exposes wild animals to increased levels of light, affecting particularly nocturnal animals. Artificial light at night might shift the balance of predator-prey interactions, for example, of nocturnal echolocating bats and eared moths. Moths exposed to light show less last-ditch maneuvers in response to attacking close-by bats. In contrast, the extent to which negative phonotaxis, moths' first line of defense against distant bats, is affected by light is unclear. Here, we aimed to quantify the overall effect of light on both types of sound-evoked antipredator flight, last-ditch maneuvers and negative phonotaxis. We caught moths at two light traps, which were alternately equipped with loudspeakers that presented ultrasonic playbacks to simulate hunting bats. The light field was omnidirectional to attract moths equally from all directions. In contrast, the sound field was directional and thus, depending on the moth's approach direction, elicited either only negative phonotaxis, or negative phonotaxis and last-ditch maneuvers. We did not observe an effect of sound playback on the number of caught moths, suggesting that light might suppress both types of antipredator flight, as either type would have caused a decline in the number of caught moths. As control, we confirmed that our playback was able to elicit evasive flight in moths in a dark flight room. Showing no effect of a treatment, however, is difficult. We discuss potential alternative explanations for our results, and call for further studies to investigate how light interferes with animal behavior.

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“…This wide range of observed approach speeds, ranging from 5 to 15 m/s, and buzz durations, ranging from 150 to 500 ms, indicate that the bats are employing a diverse set of hunting tactics at both study sites. This reflects their sensory-motor behavior likely in response to different prey types that across both study sites exhibit a suit of different evasive maneuvers (Hügel & Goerlitz, 2019) (Figure 2). This is in contrast to other mammalian synanthropic species that adjust to an urban setting by generalizing their diet (Scholz et al, 2020) or by adjusting to new food sources (Athreya et al, 2016;Bowers & Breland, 1996;Wist et al, 2022).…”

Section: Urban and Rural Bats Catch Same-sized Prey With Same Foragin...mentioning

confidence: 95%

Low foraging rates drive large insectivorous bats away from urban areas

Stidsholt,

Scholz,

Hermanns

et al. 2023

Global Change Biology

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Urbanization has significant impacts on wildlife and ecosystems and acts as an environmental filter excluding certain species from local ecological communities. Specifically, it may be challenging for some animals to find enough food in urban environments to achieve a positive energy balance. Because urban environments favor small‐sized bats with low energy requirements, we hypothesized that common noctules (Nyctalus noctula) acquire food at a slower rate and rely less on conspecifics to find prey in urban than in rural environments due to a low food abundance and predictable distribution of insects in urban environments. To address this, we estimated prey sizes and measured prey capture rates, foraging efforts, and the presence of conspecifics during hunting of 22 common noctule bats equipped with sensor loggers in an urban and rural environment. Even though common noctule bats hunted similar‐sized prey in both environments, urban bats captured prey at a lower rate (mean: 2.4 vs. 6.3 prey attacks/min), and a lower total amount of prey (mean: 179 vs. 377 prey attacks/foraging bout) than conspecifics from rural environments. Consequently, the energy expended to capture prey was higher for common noctules in urban than in rural environments. In line with our prediction, urban bats relied less on group hunting, likely because group hunting was unnecessary in an environment where the spatial distribution of prey insects is predictable, for example, in parks or around floodlights. While acknowledging the limitations of a small sample size and low number of spatial replicates, our study suggests that scarce food resources may make urban habitats unfavorable for large bat species with higher energy requirements compared to smaller bat species. In conclusion, a lower food intake may displace larger species from urban areas making habitats with high insect biomass production key for protecting large bat species in urban environments.

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Species-specific strategies increase unpredictability of escape flight in eared moths

Cited by 4 publications

References 45 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

Light might suppress both types of sound‐evoked antipredator flight in moths

Low foraging rates drive large insectivorous bats away from urban areas

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