Some dogs are more natural at this than others and that’s probably because they have a better nose.
However, dogs do mark holes in different ways and good dogs mark differently for different species.
When all’s said and done you can’t really teach a dog to mark an inhabited hole… it comes naturally, and with experience.
Then again, you can speed the process up a bit by simply getting the dog to chase the rabbit to ground and let it mark it that way.
The really important thing is not to ‘enter them’ at too early an age, 18 months is plenty soon enough; you will spoil them if it’s done any sooner.
In time your dog, whatever the breed, will mark in a distinct manner – some will stare at a hole with one foot in the air similar to the stance adopted by a pointer, others will lay or sit facing the hole.
Only the handler will notice the more discreet marks made by their dog.
Bear in mind that some dogs will mark holes at an early age even without having seen a rabbit pop down one, that’s because it’s the scent coming up from below which catches their interest.
My whippet will go into a pointer stance if a rabbit’s at home, as will my little Lurcher, Mist.
However he will shake with excitement and glare into the hole like a devil possessed if it’s a fox downstairs!