They are, and they are doing more damage to larger birds, like raptors and herons and such moreso than small songbirds. But as with anything, context is very important.

Many recent estimates have wind power killing 0.269 birds per gigawatt hour, vs 5.18 per fossils fuels. A problem with the accuracy of these numbers is that other critters can beat people to the dead birds before they get counted. Some people claim the number or bird deaths from windmills if off by a factor of 10. While very significant, that still has wind power as twice as safe for birds.

Since we’re the owl club, we can see some owl specific numbers:

The grey bar is predicted deaths, the line the upper prediction. Top scales is estimated deaths per windmill. Bottom scales is # of species for the listed order. Number is indicated by the black dot in the grey bar. There are around 250 species of owl, so you can see their black dot is around there.

Plenty of human related things cause multitudes more deaths of birds per year though. All types of habitat destruction, fossil fuels, building strikes, car strikes, and cats dwarf the number or windmill fatalities.

This article has a pretty good writeup if you want more, and if you are super smart, this is the research doc that is the primary source for the easy to read one.

Large scale wind turbines are relatively new, so we’re still learning how to mitigate there damage, some ideas are mentioned in that article, from changing the blade colors to more mindful loaction of the turbines.

Also interesting to note, the articles show bats are killed in significantly higher numbers than birds, and I’ve never heard that talked about.