scholarly journals Acoustic deterrents influence foraging activity, flight and echolocation behaviour of free-flying bats

2021 ◽  
Author(s):  
Lia R. V. Gilmour ◽  
Marc W. Holderied ◽  
Simon P. C. Pickering ◽  
Gareth Jones
Keyword(s):  
Human Impacts ◽  
Flight Speed ◽  
Masking Effect ◽  
Foraging Activity ◽  
Echolocation Call ◽  
Call Structure ◽  
Acoustic Methods ◽  
Social Calls ◽  
Direct Flight ◽  
Masking Noise

Acoustic deterrents have shown potential as a viable mitigation measure to reduce human impacts on bats, however, the mechanisms underpinning acoustic deterrence of bats have yet to be explored. Bats avoid ambient ultrasound in their environment and alter their echolocation calls in response to masking noise. Using stereo thermal videogrammetry and acoustic methods, we tested predictions that i) bats would avoid acoustic deterrents and forage and social call less in a ‘treated airspace’; ii) deterrents would cause bats to fly with more direct flight paths akin to commuting behaviour and in line with a reduction in foraging activity, resulting in increased flight speed and decreased flight tortuosity; iii) bats would alter their echolocation call structure in response to the masking deterrent sound. As predicted, overall bat activity was reduced by 30% and we recorded a significant reduction in counts of Pipistrellus pygmaeus (27%), Myotis spp. (probably M. daubentonii) (26%) and Nyctalus and Eptesicus spp. (68%) passes. P. pygmaeus feeding buzzes were also reduced by the deterrent in relation to general activity (by 38%), however social calls were not (only 23% reduction). Bats also increased their flight speed and reduced the tortuosity of their flight paths and P. pygmaeus reduced echolocation call bandwidth and start frequency of calls in response to deterrent playback, probably due to the masking effect of the sound. Deterrence could therefore be used to remove bats from areas where they forage, for example wind turbines and roads, where they may be under threat from direct mortality.

scholarly journals Behavioural mapping of a pelagic seabird: combining multiple sensors and a hidden Markov model reveals the distribution of at-sea behaviour

2013 ◽  
Vol 10 (78) ◽  
pp. 20120570 ◽  
Author(s):  
Ben Dean ◽  
Robin Freeman ◽  
Holly Kirk ◽  
Kerry Leonard ◽  
Richard A. Phillips ◽  
...  
Keyword(s):  
Markov Model ◽  
Hidden Markov Model ◽  
Hidden Markov ◽  
Habitat Preferences ◽  
Irish Sea ◽  
Foraging Activity ◽  
Multiple Sensors ◽  
Data Loggers ◽  
Direct Flight ◽  
The Irish Sea

The use of miniature data loggers is rapidly increasing our understanding of the movements and habitat preferences of pelagic seabirds. However, objectively interpreting behavioural information from the large volumes of highly detailed data collected by such devices can be challenging. We combined three biologging technologies—global positioning system (GPS), saltwater immersion and time–depth recorders—to build a detailed picture of the at-sea behaviour of the Manx shearwater ( Puffinus puffinus ) during the breeding season. We used a hidden Markov model to explore discrete states within the combined GPS and immersion data, and found that behaviour could be organized into three principal activities representing (i) sustained direct flight, (ii) sitting on the sea surface, and (iii) foraging, comprising tortuous flight interspersed with periods of immersion. The additional logger data verified that the foraging activity corresponded well to the occurrence of diving. Applying this approach to a large tracking dataset revealed that birds from two different colonies foraged in local waters that were exclusive, but overlapped in one key area: the Irish Sea Front (ISF). We show that the allocation of time to each activity differed between colonies, with birds breeding furthest from the ISF spending the greatest proportion of time engaged in direct flight and the smallest proportion of time engaged in foraging activity. This type of analysis has considerable potential for application in future biologging studies and in other taxa.

Effect of foraging activity on the shoal structure of cod (Gadus morhua)

1995 ◽  
Vol 52 (11) ◽  
pp. 2377-2387 ◽  
Author(s):  
E. M. DeBlois ◽  
G. A. Rose
Keyword(s):  
Gadus Morhua ◽  
Critical Level ◽  
Atlantic Cod ◽  
Horizontal Displacement ◽  
Foraging Activity ◽  
Laboratory Findings ◽  
Acoustic Methods ◽  
Theoretical Predictions ◽  
Shrimp Density ◽  
The Relationship

Acoustic methods used to quantify the shoaling dynamics of Atlantic cod (Gadus morhua) during their shoreward migration across the northeast Newfoundland shelf (spring 1992) showed that shoal structure and horizontal displacement were associated with the density distribution of small pelagic scatterers, for example, shrimp (Pandalus borealis). Cod speeds (to 20 km/d) were lower after encounters with shrimp (4–7 km/d). The relationship between several characteristics of the cod shoal (density, vertical spread, height off the bottom) and shrimp density was dome shaped. Internal shoal densities declined and shoal spread and height increased until shrimp densities surpassed a critical level. Above this threshold, these trends were reversed. The vertical spread of the cod shoal matched that of shrimp up to, but not beyond, a shrimp spread of 85 m. At this observed maximum in the expansion of the shoal, fish were eight body lengths apart. At all times during our survey, cod stayed within the warmer waters (> 2 °C) found at depths greater than 250 m. Our results are the first field verification of theoretical predictions and laboratory findings that shoals expand and contract in response to foraging activity and demonstrate the potential importance of cod aggregation dynamics to interpretations of trawl data.

Spatial variation in the echolocation calls of the little brown bat (Myotis lucifugus)

2013 ◽  
Vol 91 (11) ◽  
pp. 795-801 ◽  
Author(s):  
N. Veselka ◽  
L.P. McGuire ◽  
Y.A. Dzal ◽  
L.A. Hooton ◽  
M.B. Fenton
Keyword(s):  
New York ◽  
Spatial Variation ◽  
Spatial Scale ◽  
Hudson River ◽  
Myotis Lucifugus ◽  
Echolocation Call ◽  
Echolocation Calls ◽  
Call Structure ◽  
Continental Scale ◽  
Little Brown Bat

We studied spatial variation in echolocation call structure of the little brown bat (Myotis lucifugus (LeConte, 1831)) by analysing calls recorded from free-flying individuals at 1 site in Haida Gwaii, British Columbia, 1 site in Chautaqua, New York, and 20 sites along the Hudson River, New York. We controlled for factors that are often thought to lead to interspecific variation in echolocation calls (habitat, ontogeny, presence of conspecifics, recording techniques, ambient conditions), which allowed us to focus on the effect of spatial scale on call structure. As predicted, we found that at small scales (up to 1 km), there was significant geographic variation, likely owing to roost-specific signatures and group foraging activities. At intermediate scales (2–500 km), we found no differences in call structure, suggesting that populations within this area are part of a single hibernating and breeding population. Finally, echolocation call structure differed at the continental scale (>1000 km) likely because of little genetic exchange among sampled populations. Our results highlight the importance of considering the magnitude of spatial scale when examining variation in echolocation call structure.

scholarly journals Effect of traffic noise on Scinax nasicus advertisement call (Amphibia, Anura)

2019 ◽  
Vol 109 ◽  
Author(s):  
Evelina Leon ◽  
Paola M. Peltzer ◽  
Rodrigo Lorenzon ◽  
Rafael C. Lajmanovich ◽  
Adolfo H. Beltzer
Keyword(s):  
Background Noise ◽  
Traffic Noise ◽  
Dominant Frequency ◽  
Control Site ◽  
Masking Effect ◽  
Advertisement Call ◽  
Noisy Environment ◽  
Call Structure ◽  
Species Specific ◽  
Dominant Frequencies

ABSTRACT Increased anthropogenic-made sounds such as traffic noises contribute to acoustic pollution, which produces deleterious effect on song-vertebrates. We compared the advertisement call of Scinax nasicus (Cope, 1862) males in natural (as a reference or control, Site A) and Sites affected by traffic noises (Site B). Call structure was recorded and it was amplified in sonograms (software Raven Pro 1.5). Seven variables were measured on its advertisement call: duration (s), number of notes, number of pulses per note, maximum and minimum frequency (kHz), dominant frequency (kHz) and amplitude (dB). In addition, at each Site the background noise (the fundamental frequency, F0 and amplitude, dB) was measured. The amplitude of background noise reached higher values (68.02 dB) in Site B, while in Site A was lower (34.81 dB). Thus, the F0 in Site A was 6.28 kHz and in Site B it was 4.15 kHz. Frog call in noisy environment (Site B) were characterized by lesser duration (s) and number of pulses per note, higher maximum and dominant frequencies (kHz), lower minimum frequencies, and amplitude (dB) when compared with control environment (Site A). Our study highlights, that S. nasicus males shift their vocal structure in traffic noisy ponds, mainly by vocal “adjust” of their frequencies and amplitude to counteract masking effect. Finally, acoustic monitoring of anurans on noise environments should be considering the spatial, temporal and spectral overlap between noise and species-specific acoustic behaviour.

Variation in echolocation calls of Hipposideros amiger during habituation to a novel, captive environment

Behaviour ◽  
2015 ◽  
Vol 152 (7-8) ◽  
pp. 1083-1095 ◽  
Author(s):  
Y. Chen ◽  
Q. Liu ◽  
Y.G. Shao ◽  
L.J. Tan ◽  
Z.F. Xiang ◽  
...  
Keyword(s):  
Natural Habitat ◽  
Peak Frequency ◽  
The Novel ◽  
Echolocation Call ◽  
Echolocation Calls ◽  
Call Structure ◽  
In Captivity ◽  
Free Ranging ◽  
Great Leaf ◽  
Frequency Pulse

Animals alter their behaviour during habituation to novel environments. Echolocating bats exhibit remarkable flexibility in their acoustic signals to sense diverse microhabitats. Previous studies have described intra-individual variation in echolocation calls of bats in different environments, but few studies have systematically quantified these changes in detail. We investigated variation in echolocation call structure of the great leaf-nosed bat, Hipposideros armiger during habituation to a novel, captive environment. Echolocation calls of free-ranging bats were recorded in the natural habitat and in captivity over a three-week period. We found that bats exhibited significant changes in some call parameters following introduction to the novel captive environment, and some parameters changed continuously over time. We observed plasticity in peak frequency, pulse duration and pulse rate during the captive period. This suggests that variation in echolocation calls of bats in response to a novel captive environment is a progressive process, during which bats adjust echolocation call structure to habituate gradually to their surroundings.

scholarly journals EFFECTS OF CLUTTER ON ECHOLOCATION CALL STRUCTURE OF MYOTIS SEPTENTRIONALIS AND M. LUCIFUGUS

2004 ◽  
Vol 85 (2) ◽  
pp. 273-281 ◽  
Author(s):  
Hugh G. Broders ◽  
C. Scott Findlay ◽  
Ligang Zheng
Keyword(s):  
Echolocation Call ◽  
Myotis Septentrionalis ◽  
Call Structure

Echolocation call structure and intensity in five species of insectivorous bats.

1995 ◽  
Vol 198 (2) ◽  
pp. 475-489 ◽  
Author(s):  
D A Waters ◽  
G Jones
Keyword(s):  
Energy Flux ◽  
Escape Response ◽  
Free Flight ◽  
Echolocation Call ◽  
Constant Frequency ◽  
Insectivorous Bats ◽  
Call Structure ◽  
Low Intensity ◽  
Energy Flux Density ◽  
Rms Amplitude

Echolocation call intensity was measured in the laboratory for five species of British insectivorous bats in free flight and in the hand. All species showed similar call intensities of between 80 and 90 dB peSPL (peak equivalent SPL) at 1 m during flight except Plecotus auritus, whose call intensity was between 68 and 77 dB peSPL at 1 m. Calls from stationary bats were about 13 dB less intense than calls during flight. A method is proposed to measure the root mean square (rms) amplitude of echolocation calls and, hence, to calculate the energy flux density of the call. The constant-frequency calls of Rhinolophus hipposideros have energy flux densities approximately ten times higher than those of bats using frequency-modulated calls as a result of their longer durations and lower crest factors. It is argued that the low-intensity calls of P. auritus allow it to approach tympanate moths more closely before triggering their escape response.

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