Remembering on many occasions that the police have been called out thinking someone's being attacked and killed because the foxes are so vocal, it is easy to assume that the foxes are killing the cat since that's what it sounds like. Often people who have lost their chickens or rabbit to a fox for the first time and having never received problems from foxes before will describe this fox has a rogue one. If you have pets or livestock housed outside in an insecure run then it is just luck that has stopped any foxes getting in not because now you have a mensa fox visiting. Foxes can scale six foot fences and can easily squeeze through gaps of about four inch square and they are brilliant diggers. Chicken runs should be made fox proof, wire over the top and underneath.
Weld mesh is by far the better wire to use than chicken wire.
Not only can chicken wire be pulled out of shape easily but foxes can actually bite through it. Rabbit hutches again should be secure, and the same applies regarding the wire to use. Most rabbit hutches have a little piece of wood on the front that when pushed up the doors swings open. To a fox this is so easy, all hutches should be made so only a person can get in and not an animal. A simple bolt on the door will prevent this.