Yorkshire Dales, No Nets Ferreting. 

No nets ferreting rabbits.
I've been doing it this way for many many years. Notice the other dogs in the background also doing the same, They don't run in and get involved with my 2 dogs. That takes a lot of time and a lot of rabbits before they get to understand whats required. Eventually these two of mine can split on separate rabbits and retrieve what they catch without competing with each other. That took a long time.
Also the other problem is dogs chasing the horizons up on the Dales, For example they spot a rabbit and set off in a mad frenzy of excitement to catch it, They run up the hill to the top and miss it, Next thing there off chasing another rabbit they've spotted from where they now are, Off they go again even further away from owner who thought they had a well trained dog ! before you know it the dog is half a mile away having so much fun until it remembers its now lost....lol.
We have these dogs marking a warren and staying on the job even while theres rabbits sat out on top of warrens winking at us merely 40 yards away from us. That takes time and a lot of patience and usually quite a bit of quiet cursing in very loud whisper's.