How Bats Fly
Experiments that reveal the swirling air around a flying bat indicate that those mammals generate lift and thrust with their wings much differently than birds do. On the upstroke, a bird can separate the large feathers on its wings, permitting air to flow cleanly through and minimizing any downward, altitude-robbing force. Bats can't do that, because their wings are continuous, although flexible, membranes.
A review article is in Science News May 12, 2007, V. 171 N 19, Pg 293-294. The web reference is:
http://www.sciencenews.org/articles/20070512/fob6.asp
but you may not be able to access it unless you are a subscriber to Science News.
The original article is Hedenström, A., et al. 2007. Bat flight generates complex aerodynamic tracks. Science 316(May 11):894-897. Abstract available at http://www.sciencemag.org/cgi/content/a ... 6/5826/894
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