I own flushing dogs so I have encountered this circumstance before. In fact I encountered it the last few days on some Chuckars that have been hunted quite a bit and were very wild. How I handled it was giving them the sit command when they were getting close to the bird. By sitting them down it gives me time to catch up to them and even start around them to head the bird off. I can tell when the dogs are getting close to the birds when my Springer starts to squeel and yip. My Lab does better at sitting down on command at larger distances. I did have a few wild flushes from my Springer who was incredibly birdy and was having a hard time slowing down on the runners. We ended up getting 17 Valley quail and 10 Chuckars so for late season birds this was a pretty good hunt.