I regularly spot a few foxes up were I live too due to the pens down the track. Some of them are cheeky little buggers too! Last one I saw was when I was seeing Slinks to the door at 4am in the morning after a beer session, it stood there watching me for ages, I thought about inviting it in for a beer seen as it was only early
Though it never got into the hutch I think it was a fox that petrified my rabbit and guinea pig to death, they died within 2 days of each other and I can't think of any other reason why when neither of them was ill.