Sounds like a opossum to me. I had one attack in the afternoon. It tore a large gash in a hens neck, luckily it didn't tear the crop (she survived). That night we caught it dragging one of my hens out of the coop by the leg. My hubby killed it with a mag light. I read that opossums are not the most efficient hunters and will end up injuring birds a lot of times. good luck