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Excepting Myotis capaccinii, the wings' contribution to take-off performance does not correlate with foraging ecology in six species of insectivorous bat.

Gardiner JD, Altringham JD, Papadatou E, Nudds RL - Biol Open (2014)

Bottom Line: Despite distinct differences in foraging strategy, the mass specific power generated by the bats during wing induced take-off did not differ between species, with the exception of Myotis capaccinii.The poorer take-off performance of M. capaccinii could be related to either a reduction in wing-stroke amplitude to stop the wings hitting the water's surface during foraging or perhaps an effect of having very large feet.No scaling relationship between body mass and mass-specific take-off power was found, which supports earlier research on birds and insects, suggesting that the mass-specific muscle power available for flight is broadly similar across a large range of body sizes and species.

View Article: PubMed Central - PubMed

Affiliation: School of Computing, Science and Engineering, University of Salford, Salford M5 4WT, UK.

No MeSH data available.


Related in: MedlinePlus

Wing induced take-off flight data from a M. schreibersii, showing the horizontal and vertical displacement of a bat from the digitised high-speed footage.Raw data (dots) and smoothed data (crosses), using a fourth order Butterworth low pass filter with a cut-off frequency of 14 Hz, are both shown.
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f01: Wing induced take-off flight data from a M. schreibersii, showing the horizontal and vertical displacement of a bat from the digitised high-speed footage.Raw data (dots) and smoothed data (crosses), using a fourth order Butterworth low pass filter with a cut-off frequency of 14 Hz, are both shown.

Mentions: The data collected from the videos were analysed using MATLAB® R2009a (The MathWorks, Inc., 3 Apple Hill Drive, Natick, MA). To smooth the raw data (Fig. 1) high frequency noise associated with digitisation errors was removed using a low-pass 4th order Butterworth filter (cut-off 14Hz). The cut-off frequency for the filter was chosen using the method described on page 42 of Winter, which selects the frequency with the best balance between noise-reduction and signal distortion, using plots of the residuals (i.e. a measure of the difference between the smoothed data and the raw data) (Winter, 1990). The smoothed data were then used to calculate the power associated with the movement of the COM. The power associated with the movement of the COM does not take into account the aerodynamic power the bat must also produce i.e. there is a minimum requirement for lift to match body weight and thrust to equal drag. Power above this minimum aerodynamic requirement is what is seen as the acceleration of the COM. Calculating this minimum aerodynamic power is difficult, requires many assumptions to be made and is beyond the scope of this study. Furthermore, from the bat's perspective the ability to move the COM during take-off (i.e. to escape potential predation threats or improve foraging success) is the critical measure of the acceleration performance. The take-off power was, therefore, calculated as the change in kinetic and potential energy over the three wing-strokes as(1)where PCOM is the power (W) of the COM, ΔEk is the change in kinetic energy (J), ΔEp is the change in potential energy (J) and Δt is the change in time (s). The change in kinetic energy was calculated as(2)where Mb is the body mass (kg), and Vmin and Vmax are the speed at the start of the first wing-stroke and end of the third wing-stroke respectively. The change in potential energy was calculated as(3)where g is the acceleration due to gravity (ms−2), and hmin and hmax are the bat's height at the start of the first wing-stroke and end of the third wing-stroke respectively. The take-off power was divided by Mb to give the mass-specific take-off power (W/kg). Mean power, however, does not take into account fluctuations in the instantaneous power, which occur during each wing-stroke. ANOVA with a Tukey post hoc test was used to compare the mass-specific take-off power (W/kg) between the bat species. The scaling relationships of the mass-specific take-off power and wing-stroke frequency (Hz) against Mb were determined using ordinary least squares regressions. The latter as a metric of the effort each species was putting into power generation. Ordinary least squares regressions were chosen over reduced major axis regressions because the error in the Mb of the bats is likely to be significantly smaller than the error in the power calculations. All means are expressed ± standard error.


Excepting Myotis capaccinii, the wings' contribution to take-off performance does not correlate with foraging ecology in six species of insectivorous bat.

Gardiner JD, Altringham JD, Papadatou E, Nudds RL - Biol Open (2014)

Wing induced take-off flight data from a M. schreibersii, showing the horizontal and vertical displacement of a bat from the digitised high-speed footage.Raw data (dots) and smoothed data (crosses), using a fourth order Butterworth low pass filter with a cut-off frequency of 14 Hz, are both shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232763&req=5

f01: Wing induced take-off flight data from a M. schreibersii, showing the horizontal and vertical displacement of a bat from the digitised high-speed footage.Raw data (dots) and smoothed data (crosses), using a fourth order Butterworth low pass filter with a cut-off frequency of 14 Hz, are both shown.
Mentions: The data collected from the videos were analysed using MATLAB® R2009a (The MathWorks, Inc., 3 Apple Hill Drive, Natick, MA). To smooth the raw data (Fig. 1) high frequency noise associated with digitisation errors was removed using a low-pass 4th order Butterworth filter (cut-off 14Hz). The cut-off frequency for the filter was chosen using the method described on page 42 of Winter, which selects the frequency with the best balance between noise-reduction and signal distortion, using plots of the residuals (i.e. a measure of the difference between the smoothed data and the raw data) (Winter, 1990). The smoothed data were then used to calculate the power associated with the movement of the COM. The power associated with the movement of the COM does not take into account the aerodynamic power the bat must also produce i.e. there is a minimum requirement for lift to match body weight and thrust to equal drag. Power above this minimum aerodynamic requirement is what is seen as the acceleration of the COM. Calculating this minimum aerodynamic power is difficult, requires many assumptions to be made and is beyond the scope of this study. Furthermore, from the bat's perspective the ability to move the COM during take-off (i.e. to escape potential predation threats or improve foraging success) is the critical measure of the acceleration performance. The take-off power was, therefore, calculated as the change in kinetic and potential energy over the three wing-strokes as(1)where PCOM is the power (W) of the COM, ΔEk is the change in kinetic energy (J), ΔEp is the change in potential energy (J) and Δt is the change in time (s). The change in kinetic energy was calculated as(2)where Mb is the body mass (kg), and Vmin and Vmax are the speed at the start of the first wing-stroke and end of the third wing-stroke respectively. The change in potential energy was calculated as(3)where g is the acceleration due to gravity (ms−2), and hmin and hmax are the bat's height at the start of the first wing-stroke and end of the third wing-stroke respectively. The take-off power was divided by Mb to give the mass-specific take-off power (W/kg). Mean power, however, does not take into account fluctuations in the instantaneous power, which occur during each wing-stroke. ANOVA with a Tukey post hoc test was used to compare the mass-specific take-off power (W/kg) between the bat species. The scaling relationships of the mass-specific take-off power and wing-stroke frequency (Hz) against Mb were determined using ordinary least squares regressions. The latter as a metric of the effort each species was putting into power generation. Ordinary least squares regressions were chosen over reduced major axis regressions because the error in the Mb of the bats is likely to be significantly smaller than the error in the power calculations. All means are expressed ± standard error.

Bottom Line: Despite distinct differences in foraging strategy, the mass specific power generated by the bats during wing induced take-off did not differ between species, with the exception of Myotis capaccinii.The poorer take-off performance of M. capaccinii could be related to either a reduction in wing-stroke amplitude to stop the wings hitting the water's surface during foraging or perhaps an effect of having very large feet.No scaling relationship between body mass and mass-specific take-off power was found, which supports earlier research on birds and insects, suggesting that the mass-specific muscle power available for flight is broadly similar across a large range of body sizes and species.

View Article: PubMed Central - PubMed

Affiliation: School of Computing, Science and Engineering, University of Salford, Salford M5 4WT, UK.

No MeSH data available.


Related in: MedlinePlus