1. It's a made up fact. http://www.npr.org/sections/13.7/2013/02/03/170851048/do-we-...

2. Cat's killing birds doesn't make it acceptable for humans to kill birds by the tens of millions.

Both fair points, but your link states that cats' killing statistics are perhaps exaggerated, not completely false, and we don't know by how much.

My (seemingly incorrect) assumption would imply that even if we remove all wind turbines we would only make a dent of about 1/10k. It is still a reasonable observation unless we find out the cat kill stats are off by four orders of magnitude.