That's got to be a damn big, atypical cat. Eagles take out foxes. Wind energy needs to address the problem it causes because it sure isn't good for the birds.
Raptors typically pounce on prey and kill it quickly. A bird on the ground (eating, say) that is surprised is far less lethal than a bird attacking. Like I said, though, probably not eagles.
I don't think you can find one bit of statistical evidence that cats kill more hawks than windmills. Windmills should be limited to places with no birds or be redesigned to not kill off the birds. Put them offshore.