I am positive. I saw it happen out my window. I went out to see if there was anything I could do and it flew into a tree over my head so I got a good look (roo wasn't going to survive - hawk got it by the head). It returned several times that winter, even chasing a hamburg hen into the coop by...
I've lost adults to Cooper's hawks intermittently through the years. The first many years ago was a 9 lb rooster. While they do usually prefer smaller birds, if they are hungry enough they'll go for anything they can get.