There are some very large patches of thick bramble round where I am. Lots of warrens in them. Lots of hedges of bramble, hawthorn, blackthorn. Very popular rabbit dwelling places. I want to get ferrets for the first time soon. Bit worried about the digging which will be impossible in a lot of cases. Also, like u say ferrets might wander off in large patches. But still...gotta bite the bullet some time ?