This may have been posted before but I didn't find it searching. Here is a link showing foxes trying to go over, under, and through fences. The videos give a good idea of why strong fences and good planning are needed to keep these guys out of the coop.
Though the type of fox is not our red variety, they appear very similar in size etc.
http://www.environment.gov.au/biodiversity/invasive/publications/cat-fox-fence.html
Though the type of fox is not our red variety, they appear very similar in size etc.
http://www.environment.gov.au/biodiversity/invasive/publications/cat-fox-fence.html