Yes, they do kill birds. But you know what? Buildings kill a very large multiple of that and housecats a very large multiple of the buildings. So no, they're not meatgrinders. Yes, some threatened bird species were impacted disproportionally, but any change would impact them because there are so few of them left, which is usually because of other causes: Windmills tend to be situated rather closer to the habitats of large birds of prey than housecats and buildings because we left them very little habitat to begin with, and neither large birds of prey nor windmills work well in an urban setting. But taking good care of this when siting windparks can alleviate a lot of that particular concern.

So yes, the 'windmills are bird killers' theory has been debunked to the extent that it was previously pushed as a false reason to not install windpower. (See for instance: https://windmillskill.com/blog/windfarms-kill-10-20-times-mo...)

There was a whole campaign around this, including endlessly recycled gruesome material of the same 25 birds that at one time flew into a particular mill. Obviously that stuff has legs because hey, gore and something I don't want in my backyard.

I always wonder what drives people to push these issues for more than they are worth.