I personally find that there are more foxes in urban area than in the country, foxes in towns scavange more and are to me much more clever at getting what they want,
I'd also be aware of stoats weasels ferrets and mink they are on the increase too,
id bury some bricks or concrete at least a foot down round where the run rests and sit on paving slabs to prevent burrowing, a smaller mesh helps. and covering at night. only by doing this id feel safer at leaving my buns like this