There is a lot of concern about birds being killed by wind turbines.  In 2007, the National Research Council put out a report on the Environmental Impacts of Wind Energy Projects that identified a small general risk to birds & bats (at least compared to house cats!), but that some specific locations and species were at risk.  Yesterday, a student in my Global Change Ecology class sent a video link about how some wind farms along a major migratory flyway along the Texas coast are using a Merlin Radar System to detect when large flocks of birds are present.  The system stops the wind turbines when large flocks are in the vicinity of the turbines.