The aerodynamics of big ears in the brown long-eared bat Plecotus auritus

• Autorzy: Gardiner J.D. , Dimitriadis G. , Sellers W. I. , Codd J. R.
• Języki publikacji: EN

Abstrakty

EN

Wings are the most obvious adaptation bats have for powered flight and differences in wing morphology are known to correlate with flight behaviour. However, the function(s) of ancillary structures such as the ears and tail, which may also play an important role during flight, are less well understood. Here we constructed a simplified model of a bat body with ears based upon morphological measurements of a brown long-eared bat (Plecotus auritus) to examine the aerodynamic implications of flying with large ears. The forces and moments produced by the model were measured using a sensitive 6-component force and torque balance during wind tunnel testing. The large ears of the model bat produced positive lift as well as positive drag of the same order of magnitude. At small ears angles (0° to 10°), increasing the angle of the ears resulted in an increase of the lift-to-drag ratio. At higher ear angles (> 10°) separation of the flow occurred which caused a large decrease in the lift-to-drag ratio produced. To maximise the benefit from the ears (i.e., lift-to-drag ratio) our model predicts that a horizontal free flying P. auritus should hold its ears at an approximate angle of 10°. The results of the pitching moment coefficient are inconclusive in determining if the large ears are important as flight control structures. The additional drag produced by the ears has consequences for the foraging behaviour of P. auritus with reductions in its flight speed and foraging range.

Słowa kluczowe

EN

aerodynamics; big ear; ear; brown long-eared bat; bat; Plecotus auritus; Chiroptera; flight

• Wydawca: -
• Czasopismo: Acta Chiropterologica
• Rocznik: 2008
• Tom: 10
• Numer: 2
• Opis fizyczny: p.313-321,fig.,ref.

Twórcy

autor

Gardiner J.D.

• Faculty of Life Sciences, University of Manchester, Marchester, M13 9PT, U.K.

autor

Dimitriadis G.

• Department d'Aerospatiale et Mecanique, Universite de Liege, Chemin ds Chevreuils 1, 4000 Liege 1, Belgium

autor

Sellers W. I.

• Faculty of Life Sciences, University of Manchester, Marchester, M13 9PT, U.K.

autor

Codd J. R.

• Faculty of Life Sciences, University of Manchester, Marchester, M13 9PT, U.K.

Bibliografia

• 1. J. D. Altringham 2003. British bats. HarperCollins. London. 218. pp. Google Scholar
• 2. M. E. Anderson and P. A. Racey . 1991. Feeding behaviour of captive brown long-eared bats, Plecotus auritus. Animal Behaviour 42:489–493. Google Scholar
• 3. H. J. Baagøe 1987. The Scandinavian bat fauna. Pp 57–74. in Recent advances in the study of bats. M. B. Fenton, P. A. Racey, and J. M V. Rayner , editors. eds. Cambridge University Press. Cambridge. 470. pp. Google Scholar
• 4. R. Bullen and N. L. Mckenzie . 2001. Bat airframe design: flight performance, stability and control in relation to foraging ecology. Australian Journal of Zoology 49:235–261. Google Scholar
• 5. M. Canals, C. Atala, B. Grossi, and J. Iriarte-Diaz . 2005. Relative size of hearts and lungs of small bats. Acta Chiropterologica 7:65–72. Google Scholar
• 6. R. B. Coles, A. Guppy, M. E. Anderson, and P. Schlegel . 1989. Frequency sensitivity and directional hearing in the gleaning bat, Plecotus auritus (Linnaeus 1758). Journal of Comparative Physiology 165A:269–280. Google Scholar
• 7. A. C. Entwistle, P. A. Racey, and J. R. Speakman . 1996. Habitat exploitation by a gleaning bat, Plecotus auritus. Philosophical Transactions of the Royal Society: Biological Sciences 351:921–931. Google Scholar
• 8. A. C. Entwistle, P. A. Racey, and J. R. Speakman . 1997. Roost selection by the brown long-eared bat Plecotus auritus. Journal of Applied Ecology 34:399–408. Google Scholar
• 9. M. B. Fenton 1972. The structure of aerial-feeding bat faunas as indicated by ears and wing elements. Canadian Journal Zoology 50:287–296. Google Scholar
• 10. R. Galvao, E. Israeli, A. Song, X. Tian, K. Bishop, S. Swartz, and K. Breuer . 2006. The aerodynamics of compliant membrane wings modelled on mammalian flight mechanics. AIAA Paper 2006–2866. Google Scholar
• 11. D. R. Griffin 1958. Listening in the dark. Yale University Press. New Haven. 480. pp. Google Scholar
• 12. R. W. Howard 1995. Auritus — a natural history of the brown long-eared bat. William Sessions. York, UK. 154. pp. Google Scholar
• 13. M. A R. Koehl 2003. Physical modelling in biomechanics. Philosophical Transactions of the Royal Society: Biological Sciences 358B:1589–1596. Google Scholar
• 14. W. J. Maybury and J. M V. Rayner . 2001. The avian tail reduces body parasite drag by controlling flow separation and vortex shedding. Proceedings of the Royal Society: Biological Sciences 268B:1405–1410. Google Scholar
• 15. W. J. Maybury, J. M V. Rayner, and L. B. Couldrick . 2001. Lift generation by the avian tail. Proceedings of the Royal Society: Biological Sciences 268B:1143–1448. Google Scholar
• 16. U. M. Norberg 1976a. Aerodynamics of hovering flight in the long-eared bat Plecotus auritus. Journal of Experimental Biology 65:459–470. Google Scholar
• 17. U. M. Norberg 1976b. Aerodynamics, kinematics and energetics of horizontal flapping flight in the long-eared bat Plecotus auritus. Journal of Experimental Biology 65:179–212. Google Scholar
• 18. U. M. Norberg 1987. Wing form and flight mode in bats. Pp 43–56. in Recent advances in the study of bats. M. B. Fenton, P. A. Racey, and J. M V. Rayner , editors. eds. Cambridge University Press. Cambridge. 470. pp. Google Scholar
• 19. U. M. Norberg and J. M V. Rayner . 1987. Ecological morphology and flight in bats (Mammalia; Chiroptera): wing adaptations, flight performance, foraging strategy and echolocation. Philosophical Transactions of the Royal Society: Biological Sciences 316B:335–427. Google Scholar
• 20. U. M. Norberg, T. H. Kunz, J. F. Steffensen, Y. Winter, and O. von Helversen . 1993. The cost of hovering and forward flight in a nectar-feeding bat, Glossophaga soricina, estimated from aerodynamic theory. Journal of Experimental Biology 182:207–227. Google Scholar
• 21. M. K. Obrist, M. B. Fenton, J. L. Eger, and P. A. Schlegel . 1993. What ears do for bats: a comparative study of pinna sound pressure transformation in Chiroptera. Journal of Experimental Biology 180:119–152. Google Scholar
• 22. A. Song and K. Breuer . 2007. Dynamics of a compliant membrane as related to mammalian flight. AIAA Paper 2007–665. Google Scholar
• 23. D. Stinton 2001. The design of the aeroplane. Blackwell Science. London. 684. pp. Google Scholar
• 24. S. M. Swartz, M. S. Groves, H. D. Kim, and W. R. Walsh . 1996. Mechanical properties of bat wing membrane skin. Journal of Zoology (London) 239:357–378. Google Scholar
• 25. S. Swift 1998. Long-eared bats. T & AD Poyser. London. 182. pp. Google Scholar
• 26. S. Swift and P. Racey . 2002. Gleaning as a foraging strategy in Natterer's bat Myotis nattereri. Behavioral Ecology and Sociobiology 52:408–416. Google Scholar
• 27. T. A. Vaughan 1966. Morphology and flight characteristics of molossid bats. Journal of Mammalogy 47:249–260. Google Scholar
• 28. S. Vogel 1994. Life in moving fluids. Princeton University Press. Princeton. 467. pp. Google Scholar
• 29. E. Wilson 1973. Bat faunas: a trophic comparison. Systematic Zoology 22:14–29. Google Scholar