What they?re telling you is that there?s something nasty down the hole ? a ?non target species? as I call them.
This sort of reaction is more likely to occur on a day of really foul weather when all sorts of animals run for shelter, or in spring when they go underground to give birth.
Chances are your two scented a fox in time, and backed out before going too far.
I?ve lost a small number of ferrets to foxes over the years because the difference between an earth and a burrow isn?t always as obvious as many people think.
When all’s said and done a fox earth is nothing more than a scraped out rabbit hole.
Nowadays I?m in the habit of taking a terrier with me ferreting and this solves any likely problem!
If she marks the hole by sitting in front of it then I know there?s a rabbit downstairs whereas, if she growls at the hole and enters at speed then I know a fox is close by.