Are wind turbines a hazard to birdlife? Undoubtably. But fossil fuels, buildings and cars are all much worse, so those opposed to renewable energy taking the place of fossil fuels don't get to suddenly become bird lovers when it's convenient.
From "Pecking Order: Energy's Toll on Birds," by US News, August 22, 2014, here are the numbers of bird deaths in the U.S. for different types of energy generation:
I doubt it's much different in Germany, except for the numbers being proportionally smaller and without the nuclear generation. Here are the numbers for buildings, cars, and other bird killers:
Estimates of U.S. annual bird deaths, from the U.S. Fish & Wildlife Service:Source:
Building window strikes: 97-976 million per year
Communication towers: 4-5 million per year
Transmission lines: up to 174 million per year
Cars: up to 60 million per year
Pesticide poisoning: about 72 million per year
Oil and wastewater pits: up to 2 million per year
Cats: hundreds of millions per year
(An earlier version of this chart gave the year 2002 for these numbers, but it seems stripped off the current one.)
The fact is, if you like birds and want them to thrive, you'll advocate for renewable energies.