For a beekeeper to object to someone collecting a swarm that resides on your's or someone else's property would be a little disconcerting to me. It would have the potential to set a precedent that a beekeeper is responsible when bees take up residence in unwanted places. The fact of the matter is that no matter how well we manage our hives, swarms are a reality. It is part of the bee's biology and we cannot entirely prevent it. Any beekeeper who took the approach that a swarm of bees on someone else's property was "his" would in my opinion be setting himself up for all kinds of possible legal problems. Sneaking into someones apiary and pulling a couple of nucs would certainly be looked upon as stealing, both by the beekeeper and by the authorities. Attracting passing swarms to settle in equipment on ones own property (or another's property where you have permission) is an age old method of acquiring hives and I can't think of any justification for a beekeeper objecting to it in any situation.
PS: I can think of one possible scenario that you might want to avoid, if you see that a beekeeper (or anyone else for that matter) has set his/their own swarm traps, don't put your traps on the fence right next to his. While it is probably not illegal, I think it could be considered "bad form" and would present a potential for conflict (find a tree or other perch that is well on your side of the fence instead).
Last edited by Gene Weitzel; 01-26-2009 at 12:21 PM.
Reason: adding PS
"The UNKNOWN, huh? That would be SNORBERT ZANGOX over in Waycross."