Apologies because this is slightly off-topic for VA-Bird. This Scientific
American article describes recent research confirming that birds in a formation
do coordinate their flaps with the precision needed to take advantage of each
others' draft vorteces.
http://www.scientificamerican.com/article.cfm?id=migrating-birds-use-preci
Steve Johnson
Fairfax VA
http://www.scientificamerican.com/article.cfm?id=migrating-birds-use-preci