I agree that it was a hawk but, the cats behavior , eating the carcass upsets me badly. Now they got it into their cat brains that chicken tastes good. I wouldn't trust them after that.
My barn cats have free choice food full time. They kill something daily. Fed cats hunt for fun and for whatever weird social interaction they get from sharing kills.
I recently saw a hawk or young eagle try to get a pheasant. The attack only failed because my car was right there and I scared it. I'd seen the pheasant on the shoulder of the road and slowed down to avoid hitting it. This thing came in nearly straight down so fast, hard to believe really. It barreled into that pheasant talons first and feathers literally exploded into the air like someone tore open a pillow. The impact it hit that pheasant with was terrific. It saw me as it hit and the pheasant ran away due to the distraction. This happened about 40 feet away from me. Never doubt what a raptor can do.
The hens have been grumpy, but we’ve been keeping them locked up. I did let them out over the weekend when we were home & the dog was out with them. There has been a hawk hanging around once in a while, so I’m glad they’re penned up. The cats haven’t paid them any mind. One of the hens chased a cat off the water bowl last weekend. I think they’re alright together.