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Australian Journal of Zoology Australian Journal of Zoology Society
Evolutionary, molecular and comparative zoology
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RESEARCH ARTICLE
Contents Vol 56(5)

Aerodynamic cleanliness in bats

R. D. Bullen A C and N. L. McKenzie B
+ Author Affiliations
- Author Affiliations

A 43 Murray Drive, Hillarys, WA 6025, Australia.

B Department of Environment and Conservation, PO Box 51, Wanneroo, WA 6065, Australia.

C Corresponding author. Email: bullen2@bigpond.com

Australian Journal of Zoology 56(5) 281-296 https://doi.org/10.1071/ZO08059
Submitted: 13 July 2008  Accepted: 4 December 2008   Published: 29 January 2009

Abstract

In this paper we examine morphometric attributes of the airframes of 24 species of bat from Western Australia. In particular, we consider anatomical features of the ear, head, body and tail related to lift and drag optimisation as well as airflow separation control. We provide an assessment of the relative cleanliness of the species and a range of lift and drag coefficient values for use in metabolic power output modelling. The species assessed have aerodynamic cleanliness optimisations that are appropriate to the range of Reynolds’ numbers in which bats fly. Head/body relative cleanliness was consistent with, and functionally appropriate to, aspects of species foraging niche such as foraging strategy. Cleanliness of face and fineness ratio of head and body were found to be related to minimum foraging drag. Blending of the wing and body, the presence of a wing/body fillet and the texture of the pelage were found to be important. The aerodynamic optimisation of ears and tail membrane were found to correlate with foraging strategy. The interceptors had optimisations for minimum drag generation consistent with their higher foraging flight speed. Rather than being optimised for minimum drag, the air-superiority bats’ tails and ears were consistent with their highly agile but slower-foraging flight speeds. Surface bats were characterised by the absence of optimisations for low drag. The frugivore plus the nectarivore and the carnivore studied appear to be discrete optimisations.


Acknowledgements

We thank C. L. Bullen and M. H. McKenzie for field assistance and the Western Australian Department of Environment and Conservation for providing laboratory facilities. J. McRae prepared the original artwork in Fig. 4. Nadine Guthrie provided the artwork for Fig. 6 and also the modification to Fig. 4a.


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