[citation][nom]Scotteq[/nom]< Patiently awaiting the PETA protests over birds getting injured/killed while flying through the arc of the blades >[/citation]
The best bit is that it's not a problem for birds, they tend to stay away from the giant whirring things.
It is however a problem for bats, as it confuses their echolocation and they end up getting splattered. That must have some impact on the air resistance of the blades actually.
(I'm not giving an opinion on any flame worthy topics here, it's all lighthearted =]).