Makes me wonder if that is what Gatsby is actually doing (on his own, without my direction) when he points and then starts creeping toward pigeons (who are usually milling about). I will have to watch him more closely to see if he only does this when the bird he's found is on the move. He definitely has a more solid point on doves, which tend to be pretty stationary. Gats does seem to enjoy menacing and chasing pigeons, which he doesn't do with other birds. More on that in the following paragraph.
Not knowing about his past training (I got him when he was 6) and relying on the opinions of a field trainer and a couple experienced upland bird hunting friends (one w/ GSPs, the other w/ GWPs) to determine what Gats knows/doesn't know... general consensus is that he's without doubt been hunted but doesn't have the manners of a field trial dog (also he's huge and FT dogs tend to be small & quick) or competition dog. He's also a point stealing jerk who flips out if another dog gets to retrieve the shot bird, but that's another story for another day. Like I said: no manners. The dudes also think that his desire to bump pigeons (causing them to fly without stopping/pointing) could be because a lot of trainers use them and he doesn't take them seriously because he knows they're not "really hunting" when he's been exposed to them. I will absolutely admit that I don't know enough about this subject matter to agree or disagree and am very open to other interpretations of Gatsby's behaviour.
Anyhow, I've gotten completely off track (typical) and having provided a definition for the term I began to write about in the first place.
Couler is when a dog points and then begins to creep stealthily toward a located bird, usually because the bird is moving and they're trying to get it to set (sit still) to reestablish point so that the hunter can flush and shoot. From what I understand, dogs are not supposed to do this on their own and should only do so when signaled to do so by their handler either by touch or motion/gesture (or a very quiet verbal command, so as not to startle the bird).
~Click on the link below to watch an instructive and well presented video demonstrating what this looks like in an actual field setting. Trust me, it's fascintating and worth a few minutes to watch!