Cat hasn't come back and I doubt that it's a raccoon, possum, whatever else everyone else deals with. In this desert those animals wouldn't be very happy, dead or run over (I live close to a highway).
I'm thinking it had to be chick on chick violence, so I'm gonna go with that. This animal had to bite off really short chick fuzz on the silkies. I doubt the birds gave a predator the chance to bite them, they run away and hide from ground squirrels that just pass by.
If any animals which are not native to this area pester me and my animals, animal control will take care of them. I wish it wasn't their cat going on my property, it may be one of their neighbor's cat, it shouldn't be wandering around in the first place unless it's homeless.
I fired a warning shot from a BB gun (it was loud!) and their first cat never came back. That shot echoed.. It scared me. I saw a missing cat sign about their cat at the store here. Coyote, dog, or car got it. Or another person who didn't want to give it back.