Turning flight of bats

Abstract

The turning flight of six microchiropteran bat species is described. The bats' abilities to turn tightly were determined by their abilities to fly slowly and to generate high lateral accelerations. Rhinolophus ferrumequinum developed high lateral accelerations by flapping its banked wings while flying at very low speed. Plecotus auritus turned at relatively low speed and at low lateral acceleration. The other species were all moving fast as they turned and generated lateral accelerations either by developing high bank angles or by flapping their wings with low bank angles. There was a significant correlation between wing loading and turning curvature, indicating that low wing loadings improve manoeuvrability.

The small-bat-in-summer paradigm: energetics and adaptive behavioural routines of bats investigated through a stochastic dynamic model

“…For simplicity, the estimated predation threat and competition cost in the model did not differentiate between day types (Fig. 1d), but we added a slight increase in predation threat with level of energy reserves in line with published estimates of mass-dependent flight costs (Anthony & Kunz 1977;Aldridge 1987;Witter & Cuthill 1993), which broadly tally with observations of heavy individual bats being more light avoiding (Speakman 1991). We thus specify a simple pattern of light-dependent predation threat from avian diurnal raptors and an interspecific competition cost to test if this is sufficient to generate realistic diurnal activity patterns in our model bat.…”

Biomechanics in Applications

“…If a flying organism performs a banked turn, then for any given lift coefficient and bank angle, the turning radius depends directly of the wing loading or body weight per unit wing area; there is some evidence consistent with this relationship from bats in both field and obstacle course settings (Aldridge, 1986;Aldridge and Rautenbach, 1987;Stockwell, 2001). However, growing evidence suggest that differences in turning techniques (e.g., gliding versus flapping turns, Aldridge, 1987b) and changes in wing posture throughout the turn (Lentink et al, 2007) can substantially alter the turning performance. The only study to investigate the mechanisms of turning in bats suggest a more complex mechanism.…”

Turning-ascending flight of a Hipposideros pratti bat

“…Although there were no three-dimensional kinematic data generated, a common mechanism was observed for both manoeuvres with pronation of one wing and supination of the other. Multiple cameras were used by Aldridge [ 46 ] to record the flight of six different species in a flight tunnel. Three-dimensional reconstructions were done for several of them, which resulted in correlations between turning radius and various morphological parameters.…”