Flight kinematics and energetics in the little brown bat, Myotis lucifugus (Chiroptera: Vespertilionidae), with reference to the influence of ground effect

Abstract

The kinematics of flight in the little brown bat are described, both with and without the influence of ground effect. These data are used to estimate aerodynamic power costs and the reduction in power due to ground effect. The significance of ground effect to the foraging energetics of this species is discussed.

Hovering performance of Anna's hummingbirds ( Calypte anna ) in ground effect

“…Lighthill [6] pointed out that reduction of the induced velocity can be viewed as an interaction between the vortex wake generated by the wings and an opposing vortex structure actuated by the ground via a mirroring effect. Whereas the aerodynamic advantages of forward locomotion in ground effect have been modelled for birds [7][8][9], little brown bats [10] and flying fish [11] (see also [12][13][14]), the actual mechanical as well as metabolic consequences of such flight have yet to be systematically characterized. These advantages would be expected to be maximal for hovering, based on the associated power savings experimentally found for helicopters flying close to the ground [1,2,5].…”

Functional Analysis of Locomotor Apparatus of Bats

“…This allowed the study of wing kinematics from the elbow to the very tip in much detail (Norberg 1976b;Aldridge 1988;Tian et al 2006;Norberg and Winter 2006;Swartz et al 2006;Swartz et al 2007;Riskin et al 2008;etc. ).…”

“…Contrary to the elbow and more distal points of the wing, the shoulder joint position was rarely traced on motion pictures (Aldridge 1988;Swartz et al 2007), since it is technically difficult to locate even with the help of skin markers (Riskin et al 2008). The motion of the shoulder girdle is even harder to analyze since the scapula and clavicle are incorporated in the thorax.…”

“…c. Model of stroke movements modified after Altenbach and Hermanson (1987 the scapula in a wing stroke. Aldridge (1988) studied the flight of Myotis lucifugus close to water surface. In such a flight the wing depression below the body is inevitably restricted, while the elevation is significantly increased instead.…”

“…Aldridge (1988) has shown on Myotis lucifugus, that the so-called ground effect comes into action in this case, which reduces significantly the aerodynamic power cost of locomotion. So, this flight is twice advantageous, since it not only gives better chance to meet insect prey but also saves muscular expenditures of energy in the hunting voyage.…”