I've been collecting information on this topic for a while, and yesterday, I sat down to write a post that would clarify the question of the impacts of windmills on bird populations. It turns out, however, that I was totally unsatisfied with the available data on everything from windmills to building strikes to cats, so instead I wrote a post making that very point: We really have no idea. This is an interesting and important problem, though, so it is worth having a conversation about. The post is here: "How many birds are killed by windmills and other green energy projects?"
Isn't this beautiful: Story behind it from withouthotair.blogspot.com/2010/01/wind-farm-wakes.