It's not black or white—on the range of vision and echolocation in echolocating bats

Boonman, Arjan; Bar-On, Yinon M.; Cvikel, Noam; Yovel, Yossi

doi:10.3389/fphys.2013.00248

Cited by 88 publications

(87 citation statements)

References 71 publications

(85 reference statements)

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“…Bats rely on vision for long-distance orientation (23)(24)(25), are known or suspected to orient through landscapes using light cues, such as stars and postsunset glow (26,27), and use visual cues to help them find roosts in trees (28). The effects of moonlight on bat activity and fatality at turbines are not well understood, but a study in Alberta, Canada, reported higher fatality rates of silver-haired bats (Lasionycteris noctivagans) at wind turbines on nights when the moon was fully illuminated (29).…”

Section: Discussionmentioning

confidence: 99%

Behavior of bats at wind turbines

Cryan

Gorresen

Hein

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

167

222

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Wind turbines are causing unprecedented numbers of bat fatalities. Many fatalities involve tree-roosting bats, but reasons for this higher susceptibility remain unknown. To better understand behaviors associated with risk, we monitored bats at three experimentally manipulated wind turbines in Indiana, United States, from July 29 to October 1, 2012, using thermal cameras and other methods. We observed bats on 993 occasions and saw many behaviors, including close approaches, flight loops and dives, hovering, and chases. Most bats altered course toward turbines during observation. Based on these new observations, we tested the hypotheses that wind speed and blade rotation speed influenced the way that bats interacted with turbines. We found that bats were detected more frequently at lower wind speeds and typically approached turbines on the leeward (downwind) side. The proportion of leeward approaches increased with wind speed when blades were prevented from turning, yet decreased when blades could turn. Bats were observed more frequently at turbines on moonlit nights. Taken together, these observations suggest that bats may orient toward turbines by sensing air currents and using vision, and that air turbulence caused by fastmoving blades creates conditions that are less attractive to bats passing in close proximity. Tree bats may respond to streams of air flowing downwind from trees at night while searching for roosts, conspecifics, and nocturnal insect prey that could accumulate in such flows. Fatalities of tree bats at turbines may be the consequence of behaviors that evolved to provide selective advantages when elicited by tall trees, but are now maladaptive when elicited by wind turbines. energy development | sensory perception | video surveillance | wildlife | wind energy B ats are long-lived mammals with low reproductive potential and require high adult survivorship to maintain populations (1, 2). The recent phenomenon of widespread fatalities of bats at utility scale wind turbines represents a new hazard with the potential to detrimentally affect entire populations (3, 4). Bat fatalities have been found at wind turbines on several continents (3-6), with hypothesized estimates of fatalities in some regions ranging into the tens to hundreds of thousands of bats per year (4, 6). Before recent observations of dead bats beneath wind turbines, fatal collisions of bats with tall structures had been rarely recorded (7). Most fatalities reported from turbines in the United States, Canada, and Europe are of species that evolved to roost primarily in trees during much of the year ("tree bats"), some of which migrate long distances in spring and late summer to autumn (8). In North America, tree bats compose more than three-quarters of the reported bat fatalities found at wind-energy sites (6, 9), although there is a paucity of information from the southwestern United States and Mexico. Similar patterns occur in Europe (4). Another prominent pattern in bat fatality data from northern temperate zones is that most fatali...

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Section: Discussionmentioning

confidence: 99%

Behavior of bats at wind turbines

Cryan

Gorresen

Hein

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

167

222

View full text Add to dashboard Cite

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“…Some echolocating bats use vision to complement auditory information when hunting (Eklöf and Jones 2003) and, if vision and echolocation provide conflicting information, visual information is used in preference (Orbach and Fenton 2010). Vision can also be more effective than echolocation over long distances (Boonman et al 2013), and the California leaf-nosed bat Macrotus californicus relies more on vision when hunting prey under low levels of illumination equivalent to a moonlit night (Bell 1985).…”

Section: Bat Visionmentioning

confidence: 99%

Dark Matters: The Effects of Artificial Lighting on Bats

Rowse

Lewanzik

Stone

et al. 2015

Bats in the Anthropocene: Conservation of Bats in a Changing World

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While artificial lighting is a major component of global change, its biological impacts have only recently been recognised. Artificial lighting attracts and repels animals in taxon-specific ways and affects physiological processes. Being nocturnal, bats are likely to be strongly affected by artificial lighting. Moreover, many species of bats are insectivorous, and insects are also strongly influenced by lighting. Lighting technologies are changing rapidly, with the use of light-emitting diode (LED) lamps increasing. Impacts on bats and their prey depend on the light spectra produced by street lights; ultraviolet (UV) wavelengths attract more insects and consequently insectivorous bats. Bat responses to lighting are species-specific and reflect differences in flight morphology and performance; fast-flying aerial hawking species frequently feed around street lights, whereas relatively slowflying bats that forage in more confined spaces are often light-averse. Both highpressure sodium and LED lights reduce commuting activity by clutter-tolerant bats of the genera Myotis and Rhinolophus, and these bats still avoided LED lights when dimmed. Light-induced reductions in the activity of frugivorous bats may affect ecosystem services by reducing dispersal of the seeds of pioneer plants and hence reforestation. Rapid changes in street lighting offer the potential to explore

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“…By plugging in the estimated emission intensity for this species (P t ¼ 135 dB SPL [18]) and the estimated minimum intensity detectable by our microphone, a detection range of ca 20 m is reached (when solving the equation numerically with Matlab). The microphone's P r -the minimal detectable intensity (or the internal noise floor) of our microphone-was estimated by analysing the internal noise of the microphone by comparison with a calibrated microphone (40DP, GRAS).…”

Section: (D) Estimating the Acoustic Detection Range Of The Microphonementioning

confidence: 99%

“…We used miniature on-board microphones, which also include Global Positioning System (GPS), which were fitted on naturally foraging bats. We chose to study Rhinopoma microphyllum bats as these bats are known to be social [16,17], and because they focus their sound energy in a narrow frequency band [18] making them highly prone to be jammed.…”

Section: Introductionmentioning

confidence: 99%

On-board recordings reveal no jamming avoidance in wild bats

et al. 2015

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Animals often deal with situations in which vast sensory input is received simultaneously. They therefore must possess sophisticated mechanisms to select important input and ignore the rest. In bat echolocation, this problem is at its extreme. Echolocating bats emit sound signals and analyse the returning echoes to sense their environment. Bats from the same species use signals with similar frequencies. Nearby bats therefore face the difficulty of distinguishing their own echoes from the signals of other bats, a problem often referred to as jamming. Because bats commonly fly in large groups, jamming might simultaneously occur from numerous directions and at many frequencies. Jamming is a special case of the general phenomenon of sensory segregation. Another well-known example is the human problem of following conversation within a crowd. In both situations, a flood of auditory incoming signals must be parsed into important versus irrelevant information. Here, we present a novel method, fitting wild bats with a miniature microphone, which allows studying jamming from the bat's ‘point of view’. Previous studies suggested that bats deal with jamming by shifting their echolocation frequency. On-board recordings suggest otherwise. Bats shifted their frequencies, but they did so because they were responding to the conspecifics as though they were nearby objects rather than avoiding being jammed by them. We show how bats could use alternative measures to deal with jamming instead of shifting their frequency. Despite its intuitive appeal, a spectral jamming avoidance response might not be the prime mechanism to avoid sensory interference from conspecifics.

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It's not black or white—on the range of vision and echolocation in echolocating bats

Cited by 88 publications

References 71 publications

Behavior of bats at wind turbines

Behavior of bats at wind turbines

Dark Matters: The Effects of Artificial Lighting on Bats

On-board recordings reveal no jamming avoidance in wild bats

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