Echolocation and feeding behaviour of Taphozous mauritianus (Chiroptera: Emballonuridae)

1980 ◽  
Vol 58 (10) ◽  
pp. 1774-1777 ◽  
Author(s):  
M. B. Fenton ◽  
G. P. Bell ◽  
D. W. Thomas
Keyword(s):  
Long Range ◽  
Feeding Behaviour ◽  
Second Harmonic ◽  
Feeding Strategy ◽  
Rapid Rise ◽  
Constant Frequency ◽  
Insectivorous Bats ◽  
Sound Energy ◽  
Echolocation Calls ◽  
Human Ear

Observations of free-flying bats in the field in Zimbabwe indicated that Taphozous mauritianus uses multiharmonic constant frequency (CF) search calls followed by multiharmonic approach and terminal calls that combine shallow and steep frequency modulated (FM) sweeps during approaches to targets. The three phases of calls all have rapid rise times to full amplitude, and most of the sound energy is in the second harmonic; the fundamental is usually present (11–13 kHz), making the calls clearly audible to the unaided human ear. This combination of characters, but particularly the CF search calls, serves to distinguish these echolocation calls from those of other insectivorous bats. One light-tagged individual hunting insects reacted to targets at distances of about 3 m, suggesting a long-range feeding strategy.

The echolocation calls of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats as adaptations for long- versus short-range foraging strategies and the consequences for prey selection

1986 ◽  
Vol 64 (12) ◽  
pp. 2700-2705 ◽  
Author(s):  
Robert M. R. Barclay
Keyword(s):  
Prey Selection ◽  
Foraging Strategy ◽  
Prey Detection ◽  
Constant Frequency ◽  
Insectivorous Bats ◽  
Lasiurus Cinereus ◽  
Echolocation Calls ◽  
Close Range ◽  
Search Approach ◽  
Lasionycteris Noctivagans

Amongst aerial-feeding insectivorous bats, differences in the design of echolocation calls appear to be associated with differences in foraging strategy. Recordings and observations of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats in Manitoba, Canada, support such an association. Lasionycteris noctivagans use multiharmonic search–approach calls with an initial frequency sweep and a constant frequency tail. Such calls are suited for bats foraging in the open but near obstacles, and pursuing prey detected at relatively close range. This is the foraging strategy employed by this relatively slow, manoeuverable species. Lasiurus cinereus employ single harmonic search–approach calls that are low (20–17 kHz), essentially constant frequency signals. Calls of this design are suited for long-range target detection in open air situations, the foraging strategy used by L. cinereus. Differences in call design may explain dietary differences between the two species. Lasiurus cinereus consistently prey on large insects. The low, constant frequency design of their calls means that small insects are detectable only at close range and are thus difficult for this fast-dying bat to catch. The broad-band calls used by L. noctivagans do not restrict prey detection and these bats prey on a wider range of insects. Similar restrictions on prey detection, caused by echolocation call specializations, may be important in producing what might otherwise be considered active prey selection by some insectivorous bats.

Activity patterns and habitat preferences of insectivorous bats in a West African forest–savanna mosaic

2004 ◽  
Vol 20 (4) ◽  
pp. 397-407 ◽  
Author(s):  
Christoph F. J. Meyer ◽  
Christian J. Schwarz ◽  
Jakob Fahr
Keyword(s):  
Open Space ◽  
Activity Patterns ◽  
Habitat Preferences ◽  
Light Trap ◽  
Negative Influence ◽  
Foraging Activity ◽  
The Moon ◽  
Constant Frequency ◽  
Insectivorous Bats ◽  
Bat Activity

We studied activity patterns and habitat use by insectivorous bats in Comoé National Park, Ivory Coast. Bat foraging activity was quantified along five transects representing three different habitat types using acoustic monitoring and captures with mist nets and harp traps. Aerial insect abundance was assessed using a light trap; in addition shrub and tree arthropods were sampled. Bat activity was significantly and positively related to insect availability and ambient temperature, whereas increased visibility of the moon had a negative influence on flight activity. Together, these factors best explained both total bat activity and activity of bats hunting in open space and edge habitats. The interaction between temperature and light intensity was the best predictor of activity by species foraging in obstacle-rich forest habitats, however, the regression model had a low predictive value. Overall, a large proportion (c. 50%) of the variation in bat activity appeared to be a consequence of transect- and/or habitat-specific influences. We found a significant non-linear relationship between the activity of QCF (quasi-constant frequency) and FM–QCF (frequency modulated – quasi-constant frequency) bats and the phase of the moon, with lowest levels of activity occurring near full moon. We interpret this lunar-phobic behaviour as a reflection of a higher predation risk during moonlit periods. For FM (steep frequency modulated) and CF (constant frequency) bats, no significant correlation was found, although there was a trend suggesting that these bats at least were not negatively affected by bright moonlight. Foraging activity of bats was positively correlated with the abundance of atympanate moths; however, no such correlation was found for tympanate moths.

Loss compensation during subwavelength propagation of enhanced second-harmonic generation signals in a hybrid plasmonic waveguide

2018 ◽  
Vol 2 (3) ◽  
pp. 491-496 ◽  
Author(s):  
Xianqing Lin ◽  
Jian Ye ◽  
Yongli Yan ◽  
Haiyun Dong ◽  
Jianmin Gu ◽  
...  
Keyword(s):  
Second Harmonic Generation ◽  
Long Range ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Plasmonic Waveguide ◽  
Hybrid Plasmonic Waveguide ◽  
Loss Compensation

Subwavelength confinement and long-range propagation of enhanced second-harmonic generation signals was realized in a hybrid plasmonic waveguide.

Age and food hardness affect food handling by insectivorous bats

2007 ◽  
Vol 85 (9) ◽  
pp. 985-993 ◽  
Author(s):  
E.E. Fraser ◽  
M.B. Fenton
Keyword(s):  
Optimal Foraging ◽  
Feeding Behaviour ◽  
Eating Behaviour ◽  
Myotis Lucifugus ◽  
The Other ◽  
Food Handling ◽  
Insectivorous Bats ◽  
Male And Female ◽  
Food Items ◽  
And Gender

Eating behaviour can vary with age, experience, and gender, as well as food hardness. This variation can contribute to intraspecific dietary differences and may result in variable definitions of optimal foraging and decreased intraspecific competition. We quantified feeding behaviour of insectivorous bats eating hard and soft mealworm-based food items based on the bats’ ability to consume and manipulate food items, consumption time, chew frequency, and total chews to consume. Adult Myotis lucifugus (LeConte, 1831) were more successful at both consuming and manipulating mealworms and consumed mealworms more quickly, with greater chew frequency and in fewer chews, than did subadults. Adults chewed mealworm viscera more frequently than did subadults but showed no differences in the other variables. Adult Eptesicus fuscus (Beauvois, 1796) consumed mealworms more quickly and with fewer chews than did subadults but showed no differences in the other variables. There were no differences between adult and subadult E. fuscus when consuming mealworm viscera. Male and female M. lucifugus did not differ significantly when eating either mealworms or mealworm viscera. There was no change in subadult consumption time of mealworms over the summer. Age-based differences in eating abilities may play a role in defining optimal foraging and dietary composition in insectivorous bats.

ALTERNATION OF ECHOLOCATION CALLS IN 5 SPECIES OF AERIAL-FEEDING INSECTIVOROUS BATS FROM MALAYSIA

2003 ◽  
Vol 84 (1) ◽  
pp. 205-215 ◽  
Author(s):  
Tigga Kingston ◽  
Gareth Jones ◽  
Zubaid Akbar ◽  
Thomas H. Kunz
Keyword(s):  
Insectivorous Bats ◽  
Echolocation Calls

scholarly journals Echolocating bats exhibit differential amplitude compensation for noise interference at a sub-call level

2020 ◽  
Vol 223 (19) ◽  
pp. jeb225284
Author(s):  
Manman Lu ◽  
Guimin Zhang ◽  
Jinhong Luo
Keyword(s):  
Functional Role ◽  
Ambient Noise ◽  
Production Control ◽  
Constant Frequency ◽  
Vocal Production ◽  
Lombard Effect ◽  
Echolocation Calls ◽  
Noise Interference ◽  
Sound Communication ◽  
Amplitude Compensation

ABSTRACTFlexible vocal production control enables sound communication in both favorable and unfavorable conditions. The Lombard effect, which describes a rise in call amplitude with increasing ambient noise, is a widely exploited strategy by vertebrates to cope with interfering noise. In humans, the Lombard effect influences the lexical stress through differential amplitude modulation at a sub-call syllable level, which so far has not been documented in animals. Here, we bridge this knowledge gap with two species of Hipposideros bats, which produce echolocation calls consisting of two functionally well-defined units: the constant-frequency (CF) and frequency-modulated (FM) components. We show that ambient noise induced a strong, but differential, Lombard effect in the CF and FM components of the echolocation calls. We further report that the differential amplitude compensation occurred only in the spectrally overlapping noise conditions, suggesting a functional role in releasing masking. Lastly, we show that both species of bats exhibited a robust Lombard effect in the spectrally non-overlapping noise conditions, which contrasts sharply with the existing evidence. Our data highlight echolocating bats as a potential mammalian model for understanding vocal production control.

Constant-frequency and frequency-modulated components in the echolocation calls of three species of small bats (Emballonuridae, Thyropteridae, and Vespertilionidae)

1999 ◽  
Vol 77 (12) ◽  
pp. 1891-1900 ◽  
Author(s):  
M B Fenton ◽  
J Rydell ◽  
M J Vonhof ◽  
J Eklöf ◽  
W C Lancaster
Keyword(s):  
Single Frequency ◽  
Constant Frequency ◽  
Field Station ◽  
Echolocation Calls ◽  
Low Intensity ◽  
Low Duty Cycle ◽  
Frequency Components ◽  
Ca 50 ◽  
Higher Harmonic ◽  
Thyroptera Tricolor

The echolocation calls of Rhychonycteris naso (Emballonuridae), Thyroptera tricolor (Thyropteridae), and Myotis riparius (Vespertilionidae) were recorded at the Cãno Palma Field Station in Costa Rica in February 1998. All three species produced echolocation calls at low duty cycle (signal on ~10% of the time). While T. tricolor produced low-intensity echolocation calls that were barely detectable when the bats were <0.5 m from the microphone, the other two species produced high-intensity calls, readily detectable at distances >5 m. Myotis riparius produced calls that swept from about 120 kHz to just over 50 kHz in about 2 ms. We found no evidence of harmonics in these calls. Rhynchonycteris naso and T. tricolor produced multiharmonic echolocation calls. In R. naso the calls included narrowband and broadband components and varied in bandwidth, sweeping from just under 100 kHz to around 75 kHz in over 5 ms. Most calls were dominated by the higher harmonic (ca. 100 kHz), but some also included a lower one (ca. 50 kHz). The calls of T. tricolor were 5-10 ms long and dominated by a single frequency (ca. 45 kHz), sometimes with a ca. 25 kHz component. The echolocation calls of all three species included frequency-modulated and constant-frequency components. While these terms describe the components of the echolocation calls, they do not necessarily describe the bats' echolocation behaviour.

Postnatal Maturation of Primary Auditory Cortex in the Mustached Bat, Pteronotus parnellii

2010 ◽  
Vol 103 (5) ◽  
pp. 2339-2354 ◽  
Author(s):  
M. Vater ◽  
E. Foeller ◽  
E. C. Mora ◽  
F. Coro ◽  
I. J. Russell ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Second Harmonic ◽  
Tuning Curve ◽  
Primary Auditory Cortex ◽  
Constant Frequency ◽  
Low Frequencies ◽  
Postnatal Maturation ◽  
Mustached Bat ◽  
Pteronotus Parnellii

The primary auditory cortex (AI) of adult Pteronotus parnellii features a foveal representation of the second harmonic constant frequency (CF2) echolocation call component. In the corresponding Doppler-shifted constant frequency (DSCF) area, the 61 kHz range is over-represented for extraction of frequency-shift information in CF2 echoes. To assess to which degree AI postnatal maturation depends on active echolocation or/and reflects ongoing cochlear maturation, cortical neurons were recorded in juveniles up to postnatal day P29, before the bats are capable of active foraging. At P1-2, neurons in posterior AI are tuned sensitively to low frequencies (22–45 dB SPL, 28–35 kHz). Within the prospective DSCF area, neurons had insensitive responses (>60 dB SPL) to frequencies <40 kHz and lacked sensitive tuning curve tips. Up to P10, when bats do not yet actively echolocate, tonotopy is further developed and DSCF neurons respond to frequencies of 51–57 kHz with maximum tuning sharpness ( Q10dB) of 57. Between P11 and 20, the frequency representation in AI includes higher frequencies anterior and dorsal to the DSCF area. More multipeaked neurons (33%) are found than at older age. In the oldest group, DSCF neurons are tuned to frequencies close to 61 kHz with Q10dB values ≤212, and threshold sensitivity, tuning sharpness and cortical latencies are adult-like. The data show that basic aspects of cortical tonotopy are established before the bats actively echolocate. Maturation of tonotopy, increase of tuning sharpness, and upward shift in the characteristic frequency of DSCF neurons appear to strongly reflect cochlear maturation.

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