Don't really understand why feathering a turbine is not going to help. 
Stopped is stopped and the swept area is vastly diminished when stopped. 
There are other sources for power always available if the blades are stopped 
and they only need to be stopped at night if birds are migrating.

In any case, this article says it is not a problem: 
http://www.awea.org/faq/sagrillo/swbirds.html and I have seen others that 
say more-or-less the same thing.

Best,

Joe