We seem to have had the same regular visitors at night for about 5 years (but we do put food out for them). Being mostly nocturnal, many of them are killed in road accidents and if they become weak through lack of food they can pick up mange which can slowly kill them by weakening their immune system (although fox lovers can obtain a herbal remedy from from the Vulpine Society which can be added to their food which helps cure this. Jake-the-peg will be happy he doesn't live near us because of his chickens, but we've watched many of our neighbours' cats just sit in the garden at night and watch them curiously. Not once have we ever seen any of our visiting foxes ever try to attack them.