The pelage of bats (Chiroptera) and the presence of aerodynamic riblets: the effect on aerodynamic cleanliness

Abstract

We measured qualitative and quantitative aspects of the head and body pelage of 23 species of Western Australian bats. A functionally appropriate relationship was found with the normal flight speeds and foraging strategy of the bats at three levels of geometric consideration: overall fur texture, individual hair length and cuticular scale attributes (scale type, scale length and diameter, as well as sub-scale detail design). This relationship is best explained by describing the pelage surface as characterised by aerodynamic riblets. For species that utilise high-speed and aerodynamically efficient flight during commuting and foraging, riblets should reduce the skin friction drag of the head and body by up to 10%. The molossids, emballonurids and one pteropid studied have fur that falls within the non-dimensional height range that gives best aerodynamic efficiency, 8< h +<15. The carnivore studied falls marginally below this range.