I believe my girls are pretty well trained, we'll certainly compared to many I meet on a walk!! They will recall on the whistle and stop/wait if I ask them to in all situations, except if they flushed a rabbit or pheasant out and I wish that I could proof that better. We currently have a rabbit in our rabbit proofed field, no idea how it got in or where it is living but have spotted its poos! The dogs go barmy in there racing around after its scent, but unfortunately it has yet to show itself as would probably make good stop practice!!
As much as possible I avoid heavy game areas or put them back on lead if we go past but would be better to know that I could get them to stop on the whistle instead.
I do have one question though. Do even well trained gundogs still chase a flushed game if you haven't got the stop whistle in in time or do they have no interest in the chase ?
I wouldn't let he dogs go racing in the field at the moment - either a long line or under controlled hunting
The short answer to your question is no - a well trained Gundog doesn't chase anything and will stop/sit on flush - as with the springer I mentioned earlier. It really is inspirational to see these dogs at work and I guess it's the difference between pets - where the expectation is a well behaved dog in most situations / avoid situations where they are not trained to deal with them - and working dogs - where they are expected to be trained and behave in a consistent manner.
If the dog flushes *n then it should stop and wait for instruction and to be honest - it shouldn't need the stop whistle at all - it is hours of repetitive training and a bit of genetics that get the dog and handler to this standard! I can't do it without professional advice hence attending training days and 1-2-1 sessions...
* insert from the following: cats, deer, rabbits, hares, pheasants, ducks, mice, squirrels etc....