@Sheril while agreeing with the basic premise (wind turbines kill a suprisinglow number of birds) I do wonder if we are ignoring the "quality" when we just look at the quantity. I would imagine that cats mainly catch small, very common birds (sparrows, etc) while the wind turbines may kill a larger proportion of the bigger and more endagered species (birds of prey and the like).
Would be nice if there are numbers to back me up or prove me wrong.